Samsung Electronics Co SLS-2C40680700 Remote Radio Head User Manual LTE eNB System Description

Samsung Electronics Co Ltd Remote Radio Head LTE eNB System Description

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LTE eNB

System Description

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LTE eNB System Description

INTRODUCTION

Purpose

This manual describes the features, functions and configuration of LTE eNB.

Content and Organization

This manual consists of five Chapters and Abbreviations.

CHAPTER 1. Overview of Samsung LTE System

 Introduction to Samsung LTE System

 Network Configurations of Samsung LTE Network

 Functional Architecture of Samsung LTE

CHAPTER 2. Overview of LTE eNB

 Introduction to LTE eNB

 Key Functions

 Specifications

 System-to-System Interfaces

CHAPTER 3. LTE eNB Architecture

 Hardware Architecture

 Software Architecture

CHAPTER 4. Message Flows

 Call processing Message Flow

 Data Message Flow

 Network Synchronization Flow

 Alarm Signal Flow

 Loading Flow

 Operation/Maintenance Message Flow

INTRODUCTION

CHAPTER 5. Supplementary Functions and Tools

 Web-EMT

 About CLI

ABBREVIATIONS

Provides explanations of the abbreviations used throughout this manual.

Conventions

The following symbols are used in this manual. The following types of paragraphs contain

special information that must be carefully read and thoroughly understood.

NOTE

This provides references for additional information.

Revision History

EDITION DATE OF ISSUE REMARKS

1.0 06. 2011. First Edition

II © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description

TABLE OF CONTENTS

INTRODUCTION I

Purpose ....................................................................................................................................... I

Content and Organization............................................................................................................ I

Conventions................................................................................................................................II

Revision History.......................................................................................................................... II

CHAPTER 1. Overview of Samsung LTE System 1-1

1.1 Introduction to Samsung LTE System ................................................................................. 1-1

1.2 Samsung LTE Network Configuration.................................................................................. 1-2

1.3 LTE System Functional Architecture.................................................................................... 1-4

CHAPTER 2. Overview of LTE eNB 2-1

2.1 Introduction to LTE eNB........................................................................................................ 2-1

2.2 Key Functions........................................................................................................................ 2-7

2.2.1 Physical layer processing ........................................................................................... 2-7

2.2.2 Call Processing......................................................................................................... 2-10

2.2.3 IP Processing............................................................................................................ 2-12

2.2.4 SON.......................................................................................................................... 2-13

2.2.5 Convenient Operation and Maintenance .................................................................. 2-14

2.3 Specifications ...................................................................................................................... 2-16

2.4 System-to-System Interface................................................................................................ 2-18

2.4.1 Interface Architecture................................................................................................ 2-18

2.4.2 Protocol Stack........................................................................................................... 2-19

CHAPTER 3. LTE eNB Architecture 3-1

3.1 Hardware Architecture .......................................................................................................... 3-1

3.1.1 UADU ......................................................................................................................... 3-4

3.1.2 L8HU .......................................................................................................................... 3-6

3.1.3 Power supply .............................................................................................................. 3-8

3.1.4 Environmental Devices ............................................................................................. 3-10

TABLE OF CONTENTS

3.1.5 External Interface ......................................................................................................3-13

3.2 Software Architecture ..........................................................................................................3-15

3.2.1 Basic Software Architecture.......................................................................................3-15

3.2.2 CPS Block .................................................................................................................3-18

3.2.3 OAM Blocks...............................................................................................................3-21

CHAPTER 4. Message Flows 4-1

4.1 Call-Processing Message Flows...........................................................................................4-1

4.2 Data Message Flow ..............................................................................................................4-21

4.3 Network Synchronization Flow ...........................................................................................4-22

4.4 Alarm Signal Flow ................................................................................................................4-23

4.5 Loading Flow ........................................................................................................................4-24

4.6 Operation and Maintenance Message Flow .......................................................................4-25

CHAPTER 5. Supplementary Functions and Tools 5-1

5.1 Web-EMT .................................................................................................................................5-1

5.2 CLI ...........................................................................................................................................5-2

ABBREVIATION I

A ~ C ..........................................................................................................................................I

D ~ G .........................................................................................................................................II

H ~ M ........................................................................................................................................III

N ~ Q ....................................................................................................................................... IV

R ~ T ........................................................................................................................................ V

U ~ W ....................................................................................................................................... VI

IV © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

LIST OF FIGURES

Figure 1.1 Samsung LTE Network Configurations.................................................................. 1-2

Figure 1.2 Functions of E-UTRAN and EPC........................................................................... 1-4

Figure 2.1 Indoor eNB + L8HU Installation............................................................................. 2-2

Figure 2.2 Outdoor eNB + L8HU Installation .......................................................................... 2-3

Figure 2.3 LTE eNB System Interface Architecture .............................................................. 2-18

Figure 2.4 UE eNB Protocol Stack ....................................................................................... 2-19

Figure 2.5 eNB S-GW User Plane Protocol Stacks.......................................................... 2-20

Figure 2.6 eNB MME Control Plane Protocol Stacks....................................................... 2-20

Figure 2.7 eNB  eNB User Plane Protocol Stacks ........................................................... 2-21

Figure 2.8 eNB eNB Control Plane Protocol Stacks ........................................................ 2-21

Figure 2.9 eNB  LSM Interface Protocol Stacks............................................................... 2-22

Figure 3.1 Removable eNB’s Internal Configuration .............................................................. 3-2

Figure 3.2 Outdoor eNB Configuration ................................................................................... 3-3

Figure 3.3 Configuration......................................................................................................... 3-4

Figure 3.4 L8HU Configuration............................................................................................... 3-6

Figure 3.5 Power Supply........................................................................................................ 3-8

Figure 3.6 Power Diagram ..................................................................................................... 3-9

Figure 3.7 Outdoor eNB’s Heat Discharge ........................................................................... 3-10

Figure 3.8 UADU Heat-Discharge Mechanism......................................................................3-11

Figure 3.9 Sensors............................................................................................................... 3-12

Figure 3.10 UADU External Interface................................................................................... 3-13

Figure 3.11 L8HU External Interface .................................................................................... 3-14

Figure 3.12 eNB Software Architecture ................................................................................ 3-15

Figure 3.13 CPS Architecture............................................................................................... 3-18

Figure 4.1 Attach Process ...................................................................................................... 4-2

Figure 4.2 Service Request Process by UE ........................................................................... 4-4

Figure 4.3 Service Request Process by Networking .............................................................. 4-5

Figure 4.4 Detach Process by UE .......................................................................................... 4-6

Figure 4.5 Detach Process by MME....................................................................................... 4-8

Figure 4.6 X2-based Handover Process ................................................................................ 4-9

Figure 4.7 S1-based Handover Process ...............................................................................4-11

Figure 4.8 E-UTRAN-UTRAN PS Handover Process........................................................... 4-14

Figure 4.9 UTRAN-E-UTRAN PS Handover Process........................................................... 4-16

Figure 4.10 CS Fallback to UTRAN Process (UE in Active Mode, No PS HO Support)....... 4-18

Figure 4.11 CS Fallback to GERAN Process (UE in Active Mode, No PS HO Support)....... 4-19

TABLE OF CONTENTS

VI © SAMSUNG Electronics Co., Ltd.

Figure 4.12 eNB System Control and Traffic Flow ................................................................4-21

Figure 4.13 eNB Network Synchronization Flow...................................................................4-22

Figure 4.14 eNB System Alarm Flow ....................................................................................4-23

Figure 4.15 Loading Signal Flow...........................................................................................4-24

Figure 4.16 Operation and Maintenance Signal Flow ...........................................................4-25

Figure 5.1 Web-EMT Interface................................................................................................5-1

LTE eNB System Description

CHAPTER 1. Overview of Samsung

LTE System

1.1 Introduction to Samsung LTE System

The Samsung LTE system is a wireless network system supporting 3GPP Long Term

Evolution (3GPP LTE; hereafter, LTE) based services. It improved the disadvantages of

low transmission speed and the high cost of the data services provided by the existing

3GPP mobile communication system. The Samsung LTE system is a next generation

wireless network system that can provide high-speed data services at a low cost regardless

of time and location.

The Samsung LTE system supports the downlink Orthogonal Frequency Division Multiple

Access (OFDMA) transmission technology and the uplink Single Carrier (SC) FDMA

transmission technology in Frequency Division Duplex (FDD) mode, and supports a

scalable bandwidth for supporting various spectrum allocations to provide high-speed data

services. In addition, system performance and capacity have increased as a result of high-

performance hardware; the Samsung LTE system can easily accommodate a variety of

functions and services.

The Samsung LTE system consists of the evolved UTRAN Node B (eNB), Evolved Packet

Core (EPC), and LTE System Manager (LSM). The eNB is a system between the UE and

EPC, and processes packet calls by connecting to the User Equipment (UE) wirelessly in

accordance with the LTE Air standards. The EPC is between the eNB and the Packet Data

Network (PDN), and performs various control functions. The EPC consists of the Mobility

Management Entity (MME), the Serving Gateway (S-GW), and PDN Gateway (P-GW).

The LSM also provides an interface with an operator, functions to manage software,

configurations, performance, and failures as well as an ability to act as a Self-Organizing

Network (SON) server.

Supported System Specifications

The Samsung LTE system is based on the Rel-8 and Rel-9 standards of the LTE

3rd Generation Partnership Project (3GPP).

CHAPTER 1. Overview of Samsung LTE System

1.2 Samsung LTE Network Configuration

The Samsung LTE system consists of eNB, LSM, and EPC (MME, S-GW, P-GW), and its

network configurations are shown below.

RMI

MSS

EMS

ESM

EPC

P-GW

OCS

PCRF

OFCS

eNB eNB

PDN

MME S-GW

LSM

EMS

TL1

S10

X2-C

X2-U

S1-

MME

S1-U

S5/S8

S11

S6a

HSS

SNMP/FTP/UDP

Figure 1.1 Samsung LTE Network Configurations

evolved UTRAN Node-B (eNB)

The eNB is located between the UE and EPC. It processes packet calls by connecting to the

UE wirelessly according to the LTE Air standard. The eNB performs functionalities such as

transmission and receipt of wireless signals, modulation and demodulation of packet traffic

signals, packet scheduling for efficient utilization of wireless resources, Hybrid Automatic

Repeat Request (HARQ)/ARQ processing, Packet Data Convergence Protocol (PDCP) for

packet header compression, and wireless resources control.

It also performs handovers interoperating with the EPC.

Evolved Packet Core (EPC)

The EPC is a system between the eNB and PDN, consisting of the MME, S-GW and P-GW.

The MME processes control messages through the eNB and the NAS signaling protocol,

and processes the control functions for the control plane, such as mobility management,

tracking area list management, and bearer and session management for UEs.

The S-GW carries out the anchor function in the user plane between the 2G/3G access

system and the LTE system, and manages the packet transport layer for downlink/uplink data.

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LTE eNB System Description/Ver.1.0

The P-GW allocates an IP address to the UE. For mobility between the LTE system and the

non-3GPP access system, the P-GW carries out the anchor function and manages the

charging and transmission rate according to the service level.

LTE System Manager (LSM)

The LSM provides an interface to perform operations and maintenance on the eNB by the

operator, functions to manage software, configurations, performance, and failures as well

as an ability to act as a Self-Organizing Network (SON) server.

EPC System Manager (ESM)

The ESM provides the user interface for the operator to run and maintain the MME, S-GW,

and P-GW as system management activities.

Master SON Server (MSS)

The MSS interoperates with the local SON server as its higher node, performing the

optimized interoperation for the multi-LSM. The MSS can work with OSS (Operating

Support System) of the service provider who can decide whether to link them.

Home Subscriber Server (HSS)

The HSS is a database management system that stores and manages the parameters and

location information for all registered mobile subscribers. The HSS manages key data such

as the mobile subscriber’s access capability, basic services and supplementary services, and

provides a routing function to the subscribed receivers.

Policy and Charging Rule Function (PCRF)

The PCRF creates policy rules to dynamically apply the QoS (Quality of Service) and

accounting policies differentiated by service flow, or creates the policy rules that can be

applied commonly to multiple service flows. The IP edge includes the PCEF (Policy and

Charging Enforcement Function), which allows implementation of policy rules sent from

the PCRF per service flow.

Online Charging System (OCS)

The OCS sends/receives charging information required for a subscriber’s online charging

during calls.

Offline Charging System (OFCS)

The OFCS stores offline charging data and provides subscriber charging information.

CHAPTER 1. Overview of Samsung LTE System

1.3 LTE System Functional Architecture

The eNB manages UEs, which are in connected mode, at the AS (Access Stratum) level.

The MME manages UEs, which are in idle mode, at the NAS (Non-Access Stratum) level,

and the P-GW manages user data at the NAS level as well as working with other networks.

The functional architecture of E-UTRAN eNB, MME, S-GW, and P-GW according to the

3GPP standards is shown below. The eNB is structured in layers while the EPC is not.

E-UTRAN

PHY

MAC

RLC

PDCP

RRC

Dynamic Resource

Allocation (Scheduler)

eNB Measurement

Configuration & Provision

Radio Admission Control

Connection Mobility Control

RB Control

Inter Cell RRM

eNB

MME

NAS Security

Idle State Mobility

Handling

EPS Bearer Control

S-GW

Mobility Anchoring

P-GW

Packet Filtering

UE IP address allocation

EPC Internet

Figure 1.2 Functions of E-UTRAN and EPC

eNB

The eNB serves the E-UTRAN (Evolved UTRAN), a wireless access network in the LTE

system.

The eNBs are connected through the X2 interface whereas the eNB and EPC are connected

through S1 interface.

The eNB’s wireless protocol layers are divided into Layer 2 and Layer 3. Layer 2 is

subdivided into the MAC (Media Access Control) layer, RLC (Radio Link Control) layer,

and PDCP layer, each operating independently. Layer3 has the RRC layer.

The MAC layer distributes wireless resources to each bearer according to its priority, and

carries out the multiplexing function and the HARQ function for the data received from the

multiple upper logical channels.

The RLC layer carries out the following functions.

 Reconstructs the data received from the PDCP layer in accordance with the size

specified by the MAC layer (segmentation and reassembly).

 When data transmission fails in the lower layer, requests retransmission to recover

them (ARQ).

 Reorders the data recovered by performing HARQ in the MAC layer.

1-4 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

The PDCP layer carries out the following functions.

 Compresses and decompresses headers

 Encrypts and decrypts the user plane and control plane data

 Protects and verifies data integrity of the control plane

 Transmits data and manages serial numbers

 Removes data based on a timer as well as removing duplicates

The RRC layer is responsible for managing mobility in the wireless access network,

keeping and controlling the RB (Radio Bearer), managing RRC connections, and sending

system information.

Mobility Management Entity (MME)

The MME works with the E-UTRAN (eNB), handling S1-AP (S1 Application Protocol)

signaling messages in the SCTP (Stream Control Transmission Protocol) base to control

call connections between the MME and eNB as well as handling NAS signaling messages

in the SCTP base to control mobility and call connections between the UE and EPC.

The MME also works with the HSS to obtain, modify and authenticate subscriber

information, and works with the S-GW to request assignment, release and modification of

bearer paths for data routing and forwarding using the GTP-C protocol.

The MME can work with the 2G and 3G systems, SGSN, and MSC to provide mobility,

HO (Handover), CS (Circuit Service) fallback, and SMS (Short Message Service) services.

The MME is also responsible for managing mobility between eNBs, idle-mode UE

reachability, TA (Tracking Area) list as well as for P-GW/S-GW selection, authentication,

and bearer management.

MME supports the handover between MMEs and provides the mobility for the handover

between the eNBs.

It also supports the SGSN selection function upon handover to a 2G or 3G 3GPP network.

Serving Gateway (S-GW)

The S-GW carries out the mobility anchor function upon inter-eNB handover and inter-

3GPP handover, and processes routing and forwarding of packet data. The S-GW allows

the operator to set a different charging policy by UE, PDN or QCI, and manages the packet

transport layer for uplink/downlink data. The S-GW also works with the MME, P-GW, and

SGSN to support the GTP (GPRS Tunneling Protocol) and PMIP (Proxy Mobile IP).

PDN Gateway (P-GW)

The P-GW works with PCRF to carry out charging and bearer policies, and manage the

charging and transmission rate based on the service level. It also provides packet filtering

per subscriber, assigns IP addresses to UEs, and manages the packet transmission layer of

the downlink data.

CHAPTER 1. Overview of Samsung LTE System

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1-6 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description

CHAPTER 2. Overview of LTE eNB

2.1 Introduction to LTE eNB

The LTE eNB system is located between the UE and EPC, and interfaces via a wireless

connection according to the LTE Air Interface, providing subscribers with wireless

communication services. The eNB engages in sending and receiving radio signals with the

UE, and handling traffic modulation/demodulation signals. The LTE eNB is also

responsible for packet scheduling and wireless bandwidth allocation as well as for

handovers by interfacing with the EPC.

It consists of a DU (Digital Unit), i.e., UADU (Universal platform type A Digital Unit) and

a RU (Radio Unit), i.e., L8HU (LTE eNB remote radio Head Unit).

The UADU is a 19 inch shelf-type digital unit and can be mounted on a 19 inch rack in an

indoor/ outdoor environment.

The L8HU is an RF integration module consisting of a transceiver, power amplifier, and

filter. It sends and receives traffic, clock information, and alarm/control messages to and

from the L9CA. The L8HU has a 2Tx/4Rx structure with optic CPRI support, and can be

installed on a wall or pole in an outdoor environment.

CHAPTER 2. Overview of LTE eNB

The LTE eNB can be installed as shown below:

Indoor eNB + L8HU

The L9CA from the UADU mounted on an indoor 19 inch rack is connected to the L8HU.

The L8HU can be installed on a wall or pole.

Figure 2.1 Indoor eNB + L8HU Installation

2-2 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Outdoor eNB + L8HU

The L9CA from the UADU mounted on an outdoor rack is connected to the L8HU.

The L8HU can be installed on a wall or pole.

Figure 2.2 Outdoor eNB + L8HU Installation

CHAPTER 2. Overview of LTE eNB

The LTE eNB system has the following key features:

High Compatibility and Interoperability

Samsung LTE system adheres to specifications released in accordance with the 3GPP

standards, providing excellent compatibility and interoperability.

High-Performance Modular Structure

The LTE eNB system uses a high-performance processor and has a modular structure that

allows an easy hardware and software upgrade.

Support for Advanced RF and Antenna Solutions

The LTE eNB system adopted a power amplifier to support bandwidth for broadband

operation, and also supports MIMO (Multiple Input Multiple Output).

Maintenance with Enhanced Security

The LTE eNB system provides security functions (SNMPv2c, SSH, FTP/SFTP, and

HTTPs) for all channels for operation and maintenance. It authenticates operators accessing

the system, grants them permissions, and stores their system execution histories as logs.

6Rx Multi Antenna Support

Compared to generic eNBs with 2Rx antennas that receive 2Rx in one sector, Samsung

LTE eNB has enhanced reception, receiving antenna signals up to 6Rx from its own sector

as well as from the repeater mode.

OFDMA/SC-FDMA Scheme

The LTE eNB performs the downlink OFDMA/uplink SC-FDMA (Single Carrier

Frequency Division Multiple Access) channel processing that supports the standard LTE

physical layer.

The downlink OFDMA allows the system to transmit data to multiple users simultaneously

using the subcarrier allocated to each user. Depending on the channel status and the

transmission rate requested by the user, the downlink OFDM can allocate one or more

subcarriers to a specific subscriber to transmit data. Moreover, when all subcarriers are

divided for multiple users, the FDMA can select and assign to each subscriber a subcarrier

with the most appropriate features, distributing resources efficiently and increasing data

throughput.

The uplink SC-FDMA, which is similar to the modulation/demodulation method of the

OFDMA, minimizes the PAPR (Peak-to-Average Power Ratio) of the transmitter by

computing, for each user, DFT (Discrete Fourier Transform) during modulation at the

transmitting end, and IDFT (Inverse Discrete Fourier Transform) during demodulation at

the receiving end, and continuously assigns frequency resources to users. As a result, it

saves the UE’s power.

2-4 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Support for Multiple System Configurations

The LTE eNB supports multiple system and network configurations with a digital unit

(UADU) and radio unit (RRH: Remote Radio Head). The digital I/Q and C & M (Control &

Maintenance) interface based on the CPRI (Common Public Radio Interface) standard is

used between the DU and RU to send and receive data traffic signals and OAM

information, and uses optic cable physically.

The UADU and L8HU each have a power supply of DC -48 V.

 Multiple Configurations for Network Operation

The LTE eNB supports multiple configurations including RRH (L8HU).

The RRH is highly flexible in its installation, and helps with setting up a network in a

variety of configurations depending on the location and operation method.

 Easy Installation

The optic interface component that interfaces with the UADU and the RF signal

processing component is integrated into the RRH, which becomes a very small and

very light single unit. The L8HU can be installed on a wall or pole.

Moreover, as the distance between the RRH and antenna is minimized, the loss of RF

signals due to the antenna feeder line can be reduced so that the line can provide more

enhanced RF receiving performance than the existing rack-type eNB.

 Natural Cooling

Because the RRH is installed outdoors and has an efficient design, it can radiate heat

efficiently without any additional cooling system. No additional maintenance cost is

needed for cooling the RRH.

 Loopback Test

The LTE eNB provides the loopback test function to check whether communication is

normal on the Digital I/Q and C & M interface line between the DU and RU.

 Remote Firmware Downloading

Operators can upgrade the L8HU and its service by replacing its firmware.

They can download firmware to the L8HU remotely using a simple command from the

LSM without visiting field stations.

As a result, the number of visits is minimized, leading to reduced maintenance costs

and system operation with ease.

 Monitoring Port

Operators can monitor the information for an L8HU using its debug port.

MIMO Support

The LTE eNB supports 2Tx/2Rx or 4Tx/4Rx MIMO by default using multiple antennas.

MIMO has the following techniques.

 SFBC (Space Frequency Block Coding)-Downlink

 Reliability for the links is increased. (Note that the peak data rate is not increased.)

 This technology implements Space Time Block Coding (STBC) not on time but on

frequency.

 For 2 Tx: The method similar to STBC (Alamouti codes) is used.

 For 4 Tx: Both the SFBC and Frequency Switched Transmit Diversity (FSTD) are

used simultaneously.

CHAPTER 2. Overview of LTE eNB

 SM (Spatial Multiplexing)-Downlink

 This technology can increase the peak data rate by dividing and sending other data

via multiple antenna paths. (Each path uses the same time/frequency resource.)

 SU (Single User)-MIMO: SM between the eNB and single UE, it increases the

UE’s peak data rate.

 MU (Multi-User)-MIMO: SM between the eNB and multiple UEs; it increases cell

throughput instead of the UE peak data rate.

 Open-loop SM: Runs without the UE’s PMI (Precoding Matrix Indicator) feedback

when the channel changes quickly or is unknown due to the UE’s fast mobility.

 Closed-loop SM: Runs with the UE’s PMI feedback received from the eNB when

there is channel information due to the UE’s slow mobility.

 UL (Uplink) Transmit Antenna Selection-Uplink

 The UE uses one RF chain and 2Tx antennas. The eNB informs the UE which Tx

antenna to use.

 Closed-loop selection of Tx antenna

 MU (Multi-User) MIMO or Collaborative MIMO-Uplink

 SM in which two UEs use the same time/frequency resources in the UL

simultaneously to transmit different data.

 Each UE uses a single Tx antenna.

 The eNB selects two orthogonal UEs.

 There is an increase in overall cell throughput, but not in each UE’s peak data rate.

2-6 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

2.2 Key Functions

Samsung LTE eNB has the following key features.

 Physical layer processing

 Call processing

 IP processing

 SON

 Convenient operation and maintenance

2.2.1 Physical layer processing

The LTE eNB sends/receives data via wireless channels between the eNB and UE.

The eNB handles the following:

 Downlink reference signal generation/transmission

 Downlink synchronization signal generation/transmission

 Channel encoding/decoding

 Modulation/demodulation

 Resource allocation and scheduling

 Link adaptation

 HARQ

 Power control

 ICIC

 MIMO

Downlink reference signal generation/transmission

The reference signal is used to demodulate downlink signals in the UE, and to measure the

characteristics of the channel for scheduling, link adaptation, and handover.

Cell-specific and UE-specific reference signals are used when transmitting non-MBSFN.

The cell-specific reference signal is used to measure the quality of the channel, calculate

the MIMO rank, perform MIMO precoding matrix selection, and measure the strength of

the signals for handover. To operate MIMO, a different reference signal is sent for each

antenna path.

Downlink Synchronization Signal Generation/Transmission

The synchronization signal is used to perform the initial synchronization when the UE

starts to communicate with the base station. It can be PSS (Primary Synchronization

Signal) or SSS (Secondary Synchronization Signal). The UE obtains cell identify through

the synchronization signal, and other cell information through the broadcast channel.

Transmission in the synchronization signal and broadcast channel occurs at 1.08 MHz of

the cell’s channel bandwidth as the UE can identify cell ID and other basic information

regardless of the eNB’s transmission bandwidth.

CHAPTER 2. Overview of LTE eNB

Channel encoding/decoding

The LTE eNB encodes/decodes the channel to correct channel errors over the wireless

channel. To do this, the LTE eNB uses turbo coding and 1/3 tail-biting convolutional

coding. Turbo coding is used primarily to transmit large downlink/uplink data packets, and

1/3 tail-biting convolutional coding to transmit downlink/uplink control information and

for the broadcast channel.

Modulation/Demodulation

When receiving downlink data from the upper layer, the LTE eNB processes it through the

baseband procedure of the physical layer and then transmits it via a wireless channel.

At this time, to send the baseband signals as far as they can go via the wireless channel, the

LTE eNB modulates them and sends them on a specific high frequency bandwidth.

For the uplink, the eNB demodulates the data transmitted over the wireless channel from

the UE to a baseband signal, which is then decoded.

Resource Allocation and Scheduling

For multiple access, the LTE uses the OFDMA for downlink and the SC-FDMA for uplink.

Both schemes allocate 2-dimensional time/frequency resources to multiple UEs in a cell,

allowing a single eNB to communicate with the multiple UEs simultaneously.

When in MU-MIMO mode, several UEs can use the same resources at the same time as an

exceptional case. Allocating cell resources to multiple UEs is called ‘scheduling’ and each

cell has an independent scheduler.

The scheduler is designed to consider the channel environment, the requested data

transmission rate and other various QoS factors of each UE, and perform an optimal

resource allocation to provide maximum total cell throughput. It also can share information

with other cell schedulers via the X2 interface to reduce interferences with the other cells.

Link Adaptation

The transmission rate and channel environment in the wireless channel change according to

circumstances. Link adaptation is a feature to increase transmission speed or maximize

overall cell throughput using channel circumstances when they are known.

MCS (Modulation Coding Scheme) is a link adaptation method that sets the modulation

type and channel coding rate depending on the channel circumstances. If the channel

circumstances are good, the MCS increases the number of transmission bits per symbol

using high-order modulation, such as 64 QAM. If the circumstances are bad, it uses low-

order modulation, such as QPSK, and a low coding rate to minimize channel errors.

The MCS can run in MIMO mode if the channel environment allows MIMO, increasing

the user’s peak data rate or cell throughput.

If channel information turns out to be different from the actual case, or if the order given to

the modulation or coding rate for the channel circumstances is higher than necessary, an

error can occur, but be recovered by HARQ.

2-8 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

HARQ

HARQ is a technique for physical layer retransmission using the stop-and-wait protocol.

The LTE eNB runs the HARQ, retransmitting or combining frames in the physical layer in

order to increase throughput so that the impact from changes of the wireless channel

environment or interference signal level can be minimal. The LTE uses the IR (Incremental

Redundancy)-based HARQ. The CC (Chase Combining) method is treated as a special case

of the IR scheme. It uses the asynchronous IR for downlink, and the synchronous IR for

uplink.

Power Control

Power control refers to adjusting the transmission power level required to transmit a

specific data rate. Too much power causes interferences. Too little power increases the

error rate, causing a retransmission or delay.

Power control is less important in the LTE than in the CDMA, but a proper power control

can enhance the LTE’s system performance. The LTE uses the SC-FDMA scheme for

uplink and eliminates the near-far problem from the CDMA, but the UEs should transmit

with optimal power to avoid interference with neighbor cells as the high level of

interference with the neighbor cells can worsen the uplink performance. The LTE uplink

can lower the inter-cell interference level by adjusting the UE power. The downlink can

lower the inter-cell interference level by transmitting with optimal power according to the

UE location and MCS, increasing overall cell throughput.

Inter-Cell Interference Coordination (ICIC)

Unlike the CDMA, the LTE does not have intra-cell interference. This is because UEs in a

cell use orthogonal resources and thus there is no interference between them. However, in

the event that the adjacent cells are considered, unavoidable interference occurs when other

UEs use the same resource. Since this symptom is severe between the UEs located on a cell

edge, performance on the cell edge may be degraded. Inter-cell interference is not severe

for the UEs located close to the eNB because they receive much less interference from the

adjacent eNBs than the UEs located on the cell edge. A technique used to address the inter-

cell interference problem on the cell edge is ICIC.

ICIC allows interference signals to be transmitted to other cells in the cell edge area in as

small an amount as possible by allocating a basically different resource to each UE that

belongs to a different cell and by carrying out power control according to the UE’s location

in the cell. To prevent interference due to resource conflict on the cell edge, ICIC transmits

scheduling information between base stations via the X2 interface. When the neighbor

cell’s interference signal strength is too strong, ICIC notifies other base stations to control

the interference, improving overall cell performance.

MIMO

The LTE eNB supports 2Tx/2Rx or 4Tx/4Rx MIMO by default using multiple antennas.

To achieve this, there must be in the eNB channel card the RF part that can separately

process the baseband part and each path for MIMO processing. The LTE eNB provides

high-performance data services by supporting several types of MIMO.

CHAPTER 2. Overview of LTE eNB

2.2.2 Call Processing

Cell Information Transmission

The LTE eNB periodically transmits, within the cell range being served, system information,

i.e., the MIB (Master Information Block) and SIBs (System Information Blocks), which are

then received by UEs to process calls appropriately.

Call Control and Air Resource Assignment

The LTE eNB allows the UE to be connected to or released from the network.

When the UE is connected to or released from the network, the LTE eNB sends and

receives the signaling messages required for call processing to and from the UE via the Uu

interface, and to and from the EPC via the S1 interface.

When the UE connects to the network, the eNB carries out call control and resource

allocation required for service. When the UE is released from the network, the eNB collects

and releases the allocated resources.

Handover Processing

The LTE eNB supports intra-frequency or inter-frequency handover between intra-eNB

cells, X2 handover between eNBs, and S1 handover between eNBs, and carries out the

signaling and bearer processing functions required for handover. At intra-eNB handover,

handover-related messages are transmitted via internal eNB interfaces; at X2 handover, via

the X2 interface; at S1 handover, via the S1 interface.

The eNB carries out the data forwarding function to minimize user traffic disconnections at

X2 and S1 handovers. The source eNB provides two forwarding methods to the target eNB,

direct forwarding via the X2 interface and indirect forwarding via the S1 interface.

The eNB allows the UE to receive traffic without loss through the data forwarding method

at handover.

Handover Procedure

For more on the handover procedure, refer to Chapter 4. Message Flow.

Admission Control (AC)

The LTE eNB provides capacity-based and QoS-based admission control for bearer setup

requests from the EPC to avoid system overload. Capacity-based admission control and

QoS-based admission control operate as follows respectively.

 Capacity-based admission control

There is a threshold for the maximum number of connected UEs (new calls/handover

calls) and a threshold for the maximum number of connected bearers that can be

allowed in the eNB. When a call setup is requested, the permission is determined

depending on whether the connected UEs and bearers exceed the thresholds.

2-10 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

 QoS-based admission control

The eNB provides the function for determining whether to permit a call depending on

the estimated PRB usage of the newly requested bearer, the PRB usage status of the

bearers in service, and the maximum acceptance limit of the PRB (per bearer type,

QCI, and UL/DL).

RLC ARQ

The eNB carries out the ARQ function for the RLC Acknowledged Mode (AM) only.

The RLC can increase reliability of data communications by dividing the Service Data Unit

(SDU) into the Protocol Data Unit (PDU) prior to transmission, and retransmitting the

packets according to ARQ feedback from the receiver.

QoS Support

The eNB receives the QoS Class Identifier (QCI) in which the QoS characteristics of the

bearer are defined, and the Guaranteed Bit Rate (GBR), the Maximum Bit Rate (MBR),

and the Aggregated Maximum Bit Rate (AMBR) from the EPC. It provides the QoS for the

wireless section between the UE and the eNB and the backhaul section between the eNB

and the S-GW.

In the wireless section, it carries out retransmission to satisfy the rate control due to the

GBR/MBR/AMBR value, priority of bearer defined in the QCI, and scheduling considering

packet delay budget, and Packet Loss Error Rate (PLER).

In the backhaul section, the eNB carries out QCI-based packet classification, QCI to DSCP

mapping, and marking for the QoS. The eNB provides queuing based on mapping results,

and each queue transmits packets to the EPC according to strict priority, etc.

In the EMS (Element Management System), besides the QCI predefined in the

specifications, an operator specific QCI and a QCI-to-DSCP mapping can be set.

CHAPTER 2. Overview of LTE eNB

2.2.3 IP Processing

IP QoS

The LTE eNB can provide the backhaul QoS when communicating with the EPC by

supporting the Differentiated Services (DiffServ).

The LTE eNB supports eight backhaul QoS classes as well as mapping between the user

traffic service class and the backhaul QoS class. It also supports mapping between the

Differentiated Services Code Points (DSCP) and the 802.3 Ethernet MAC service classes.

IP Routing

The LTE eNB provides several Ethernet interfaces and stores in the routing table

information on which Ethernet interface IP packets will be routed.

The LTE eNB’s routing table is configured by the operator. The table configuration and its

setting are similar to standard router settings.

The LTE eNB supports static routing settings, but doesn’t support dynamic routing

protocols such as OSPF (Open Shortest Path First) or BGP (Border Gateway Protocol).

Ethernet/VLAN Interfacing

The LTE eNB provides Ethernet interfaces, and supports static link grouping, VLAN

Virtual Local Area Network(VLAN), and Ethernet Class of Service(CoS) functions that

comply with IEEE 802.3ad for Ethernet interfaces. A MAC bridge defined in IEEE 802.1D

is excluded.

The LTE eNB allows multiple VLAN IDs for an Ethernet interface. To support the Ethernet

CoS, it maps the DSCP value of the IP header to the CoS value of the Ethernet header for

Tx packets.

2-12 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

2.2.4 SON

System Self-Configuration and Self-Establishment

The self-configuration and the self-establishment automatically configure and establish

radio parameters between the power-on stage and the service stage to minimize efforts in

installing a base station. The detailed functions are as follows.

 Self-configuration

 Initial PCI (Physical Cell Identity) self-configuration

 Initial neighbor information self-configuration

 Initial PRACH (Physical Random Access Channel) self-configuration

 Self-establishment

 Automatic IP address acquisition

 Automatic OAM connectivity

 S/W and Configuration data loading

 Automatic S1/X2 setup

 Self-test

Self-Optimization

 PCI auto-configuration

The SON server of the LSM provides the function for allocating the initial PCI in the

self-establishment procedure of a new eNB, and the function for detecting a problem

automatically and selecting, changing, and setting a proper PCI when a PCI

collision/confusion occurs with the adjacent cells during operation.

 Automatic Neighbor Relation (ANR) optimization

ANR optimization minimizes the network operator’s effort to maintain the optimal

NRT by dynamically managing the Neighbor Relation Table (NRT) according to the

addition/removal of neighbor cells. It needs to automatically configure each eNB’s

initial NRT, and recognize environment changes, such as cell addition/removal or new

eNB installations during operation to maintain the optimal NRT. In other words, the

ANR function updates the NRT for each eNB by automatically recognizing the

topology change such as new adjacent cell or eNB installation/removal and adding or

removing the Neighbor Relation (NR) to or from a new adjacent cell.

 Mobility robustness optimization

The mobility robustness optimization function is the function for improving handover

performance in the eNB by recognizing the problem that handover is triggered at the

incorrect time (e.g., too early or too late) before, after, or during handover depending

on UE mobility, or handover is triggered to the incorrect target cell (handover to the

wrong cell) and then by optimizing the handover parameters according to the reasons

for the problem.

 Energy Saving Management (ESM)

The energy saving feature helps reduce the LTE eNB’s power consumption. The ESM

adjusts power consumption automatically according to the specified schedule or

through traffic quantity analysis. The basic principle is that power consumption is

reduced by limiting the number of used Resource Blocks (RBs) and adjusting the PA

bias voltage.

CHAPTER 2. Overview of LTE eNB

 Random Access Channel (RACH) optimization

RACH optimization (RO) can minimize access delay and interference by dynamically

managing parameters related to random access. The RO function is divided into the

initial RACH setting operation and the operation for optimizing parameters related to

the RACH. The initial RACH setting operation is for setting the preamble signatures

and the initial time resource considering the neighbor cells. The operation for

optimizing parameters related to the RACH is for estimating the RACH resources,

such as time resource and subscriber transmission power required for random access,

that change depending on time, and for optimizing the related parameters.

2.2.5 Convenient Operation and Maintenance

The LTE eNB works with management systems (LSM, Web-EMT, CLI) to operate

maintenance activities, such as resetting/restarting a system as well as managing system

configurations, failure/status/diagnosis of system resources and services, statistics on

system resources and various performance data, and security for system access and operation.

Graphics and Text Based Console Interfaces

The LSM manages the entire eNB system using the Database Management System (DBMS).

The eNB also works with a console terminal to allow the operator to connect directly to the

Network Element (NE), not through the LSM, for operation and maintenance activities.

The operator can choose between the graphic-based console interface (Web-EMT, Web-

based Element Maintenance Terminal) or the text-based Command Line Interface(CLI) to

suit operational convenience and purpose.

The operator can access the console interfaces without separate software. For the Web-EMT,

the operator can log in to the system using Internet Explorer. For the CLI, the operator can

Tasks such as managing configurations and operational information, failures and statuses,

and monitoring statistics can be done through the terminal. However, increasing/decreasing

resources or configuring neighbor lists in which multiple NEs are related can only be

performed using the LSM.

Operator Authentication

The eNB can authenticate system operators and manage their privileges.

An operator accesses the eNB using the operator’s account and password through the CLI.

The eNB grants an operational privilege in accordance with the operator’s level.

The eNB logs successes/failures of access to the CLI, activities during the login, etc.

Maintenance with Enhanced Security

The eNB supports the SNMP (Simple Network Management Protocol) and SFTP (SSH File

Transfer Protocol) for security during communications with the LSM, and the HTTPs

(Hyper Text Transfer Protocol over SSL) and SSH (Secure Shell) during communications

with the console terminal.

2-14 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Online Software Upgrade

When a software package is upgraded, the EPC can upgrade the existing package while it is

still running. A package upgrade is performed in the following steps: download new

package (Add) and change to the new package (Change).

When upgrading the package, the service stops temporarily during the ‘change to the new

package’ step to exit the existing process and start the new process. But the operating

system does not restart, so it can provide the service within several minutes.

After upgrading the software, the eNB updates the package stored in the internal

nonvolatile storage.

Call Trace

When tracing calls for a specific UE using the MME, the eNB transmits to the LSM a

signaling message for the call in the UE.

OAM Traffic Throttling

The eNB provides the operator with the function for suppressing the OAM-related traffic

that can occur in the system using an operator command. At this time, the target OAM-

related traffic includes the fault trap messages for alarm reporting and the statistics files

generated periodically.

For the fault trap messages, the operator can suppress generation of alarms for the whole

system or some fault traps using the alarm inhibition command, consequently allowing the

operator to control the amount of alarm traffic that is generated. For the statistics files, the

operator can control the amount of statistics files by disabling the statistics collection

function for each statistics group using the statistics collection configuration command.

CHAPTER 2. Overview of LTE eNB

2.3 Specifications

Capacity

The following table shows LTE eNB’s capacity.

Item Specifications

Air specification FDD LTE

Operating Frequency DL: 728~746 MHz

UL: 698~716 MHz

Channel Bandwidth 5 MHz

Capacity 1/2 Carrier/3Sector

RF Power per Sector 40 W (2 Tx Path)

Backhaul Links 100/1000 Base-T (RJ-45, 2 ports)

1000 Base-SX/LX (SFP, 2 ports)

DU-RRH Interface CPRI 4.0 (Optic)

Holdover 24 h

Input Power

The following table shows the power specifications of the LTE eNB. The LTE eNB

complies with UL60950 safety standard for electrical equipment.

Item Specifications

System Input Voltage 220 V AC (input voltage of the single outdoor station system)

UADU

L8HU

-48 VDC

Dimensions and Weight

The following table shows the size and weight of LTE eNB.

Item Specifications

UADU 434(W) × 385(D) × 88(H) Size(mm)

L8HU 450(W) × 175(D) × 390(H)

UADU 12 or less Weight (kg)

L8HU 23 or less

The following table shows the size and weight of the outdoor rack of LTE eNB.

Item Specifications

Size (mm) 700 (W) × 820 (D) × 1,800 (H)

Weight (kg) Approx. 370 or less (with 1 set of battery)

2-16 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

GPSR Specifications

The following table shows the features of LTE eNB’s GPSR (GPS Receiver).

Item Specifications

Received Signal from GPS GPS L1 Signal

Accuracy/Stability 0.02 ppm

Ambient Conditions

The following table shows the ambient conditions and related standard of the outdoor rack.

Item Range Applicable Standard

Temperature -20~50°C GR-487-CORE Sec.3.26

Humidity 5~95%

The moisture content must not

exceed 30 g per 1 m3 of air.

GR-63-CORE Sec.4.1.2

GR-487-CORE Sec.3.34.2

(Issue 2, April, 2002) R3-204

Altitude -60~1,800 m GR-63-CORE Sec.4.1.3

Earthquake Earthquake (Zone4) GR-63-CORE Sec.4.4.1

Vibration - Office Vibration

- Transportation Vibration

GR-63-CORE Sec.4.4.4

GR-63-CORE Sec.4.4.5

Noise (sound pressure level) Less than 65 dBA measured at

point 1.5 m above the floor and

0.6 m all around

GR-63-CORE Sec.4.6

GR-487-CORE Sec.3.29

The following table shows the ambient conditions and related standard of the L8HU.

Item Range Applicable Standard

Temperature -40~50°C GR-487-CORE Sec.3.26

Humidity 10~95%

The moisture content must not

exceed 30 g per 1 m3 of air.

GR-487-CORE Sec.3.34.2

(Issue 2, April, 2002) R3-204

Altitude -60~1,800 m GR-63-CORE Sec.4.1.3

Earthquake Earthquake (Zone4) GR-63-CORE Sec.4.4.1

Vibration - Office Vibration

- Transportation Vibration

GR-63-CORE Sec.4.4.4

GR-487-CORE Sec.3.35.5

GR-63-CORE Sec.4.4.5

GR-487-CORE Sec.3.35.3

Noise (sound pressure level) FAN less -

Electromagnetic Interference

(EMI)

Complied FCC Title47 Part 15 Class B

GR-1089-CORE

EN 55022, EN 55024

EN 301 489

CHAPTER 2. Overview of LTE eNB

2-18 © SAMSUNG Electronics Co., Ltd.

SGSN

HSS

eNB

eNB LSM-R

S-GW P-GW

PCRF

UTRAN

GERAN

MME

Iu-PS S4

LTE-Uu S1-U S5 SGi

S10

SNMP/

FTP

LTE-Uu

S1-MME S11

S6a Gxc Rx

Operator’

IP S i

EPC

2.4 System-to-System Interface

2.4.1 Interface Architecture

The LTE eNB system provides the following interface to allow interoperation between NEs.

Figure 2.3 LTE eNB System Interface Architecture

 Interface between UE and eNB

A physical connection between the UE and eNB is established via radio according to

LTE Air Interface, and the interface standards should satisfy the LTE Uu interface.

The UE interfaces and communicates data with the eNB via radio.

 Interface between eNB and EPC

A physical connection between the eNB and EPC is established through the FE (Fast

Ethernet) and GE (Gigabit Ethernet), and the interface standards should satisfy the

interface between the S-GW and LTE S1-U for the user plane, and the interface

between the MME and S1-MME for the control plane.

 Interface between eNBs

A physical connection between the eNBs is established through the FE and GE, and

the interface standards should satisfy the LTE X2 interface.

 Interface between eNB and LSM

A physical connection between the eNB and LSM is established through the FE and

GE, and the interface standards should satisfy the SNMP/FTP interface.

LTE eNB System Description/Ver.1.0

2.4.2 Protocol Stack

The protocol stack between NEs in the eNB system is as follows:

Interface between UE and eNB

The user plane protocol stack consists of PDCP, RLC, MAC, and PHY layers. The user

plane is responsible for transmitting user data (e.g., IP packets) received from the higher

layer. All protocols in the user plane are terminated in the eNB.

The control plane protocol stack consists of NAS, RRC, PDCP, RLC, MAC, and PHY

layers. Located above the wireless protocol, the NAS layer is responsible for UE

authentication between the UE and MME, security control, and paging/mobility

management of UEs in LTE idle mode.

In the control plane, all protocols except the NAS signal are terminated in the eNB.

NAS

RRC

PDCP

RLC

MAC

NAS

S1-AP

SCTP

RRC

PDCP

RLC

MAC

S1-AP

SCTP

UE LTE-Uu eNB

Relay

MME S1-MME

Figure 2.4 UE eNB Protocol Stack

CHAPTER 2. Overview of LTE eNB

Interface between eNB and EPC

A physical connection between the eNB and EPC is established through the FE and GE,

and the interface standards should satisfy the interface between the LTE S1-U and S1-

MME. The user plane uses the GTP-U (GTP-User) above the IP, and the control plane uses

the SCTP above the IP.

The user plane protocol stacks between the eNB and S-GW are shown below.

eNB

UDP

S-GW

S1-U

UDP

GTP-U GTP-U

User Plane

PDUs

User Plane

PDUs

Figure 2.5 eNB S-GW User Plane Protocol Stacks

The control plane protocol stacks between the eNB and MME are shown below.

eNB

MME

SCTP SCTP

S1-MME

S1-AP S1-AP

Figure 2.6 eNB MME Control Plane Protocol Stacks

2-20 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Interface between eNBs

A physical connection between the eNBs is established through the FE and GE, and the

interface standards should satisfy the LTE X2 interface. The user plane protocol stacks

between the eNBs are shown below.

eNB

UDP

eNB

UDP

GTP-U GTP-U

PDUs

User Plane

PDUs

User Plane

Figure 2.7 eNB  eNB User Plane Protocol Stacks

The control plane protocol stack is shown below.

eNB

SCTP SCTP

X2-AP X2-AP

Figure 2.8 eNB eNB Control Plane Protocol Stacks

CHAPTER 2. Overview of LTE eNB

Interface between eNB and LSM

A physical connection between the eNB and LSM is established through the FE and GE,

and the interface standards should satisfy the FTP/SNMP interface. The interface protocol

stacks between the eNB and LSM are shown below.

eNB

LSM

TCP UDP TCP UDP

FTP/SNMP

SNMPFTP

Figure 2.9 eNB  LSM Interface Protocol Stacks

Physical Interface Options

The LTE eNB provides two types (copper and optic) for the EPC interface, which can be

selected based on network configurations. The interface can be used in any number

according to the LTE eNB capacity and required bandwidth.

The interface types are shown below.

Interface Type Port Type Maximum Number of Ports per System

Copper 1000 Base-T (RJ-45) 2

Optic 1000 Base-LX/SX (SFP) 2

2-22 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description

CHAPTER 3. LTE eNB Architecture

3.1 Hardware Architecture

The LTE eNB system consists of a digital unit, UADU, and a radio unit, L8HU, of a

common platform. The UADU connects with the L8HU through the CPRI, and is capable

of 2-carrier/3-sector services.

CHAPTER 3. LTE eNB Architecture

LTE eNB’s Internal Configuration

The following figure shows the internal configuration of the LTE eNB.

UADA

UAMA

L9C

(CPRI Optic interface Max.6)

EPC

GPS

TEST

nalog 10 MHz/

1PPs

Clock

UDE UDA

GE Traffic +

Alarm/Control +

Clock

333

α secto

(3 lines)

sec

(3 lines) γsec

(3 lines)

Rectifier

PDP

Ethernet

-48 VDC

Backhaul interface (FE/GE)

FE/GE

LTE Outdoor Rack

Traffic + Alarm/Control + Clock

CPRI Optic

-48 VDC

Clock

Rectifier Ethernet Interface

External Interface (UDA, UDE)

Analog IF

8HU (LTE 700 MHz, 2Tx4Rx) L

Figure 3.1 Removable eNB’s Internal Configuration

2Tx/4Rx is supported by default in the UADU, and up to three L9CAs (LTE eNB Channel

card board Assembly) can be mounted additionally. A maximum of 5 MHz 2-carrier/3-sector

can be supported.

The L9CA has a capacity of 5MHz 2-carrier/3-sector (2Tx/2Rx) per board, by default.

The four slots of the UADU are multi-board type slots where the UAMA carries out the

main processor function, network interface function, clock generation and distribution

function, provider-requested alarm processing, etc. and the L9CA carries out the modem

function. The power module, FAN, and dust filter are also installed.

3-2 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

The L8HU is an RF integration module consisting of a transceiver, power amplifier, and

filter. It sends and receives traffic, clock information, and alarm/control messages to and

from the L9CA. It has a 2Tx/4Rx structure with optic CPRI support.

The following shows the configuration of LTE’s outdoor eNB.

DC Distribution

UADU

User Space

Reserved Battery

Space

Battery

Fan

Rectifier

Smartpack

I/O Monitor

Figure 3.2 Outdoor eNB Configuration

CHAPTER 3. LTE eNB Architecture

3.1.1 UADU

The following shows the configuration of the UADU.

Power

Dust Filter

UAMA

FANM-C4

L9CA

Figure 3.3 Configuration

The UADU is the Multi-board type in which the UAMA that carries out the main processor

function, network interface function, and clock creation and distribution function and the

L9CA that carries out the modem function are mounted. It consists of the power module,

FANM-C4 module, and dust filter.

The UADU is mounted on a 19 inch rack, with fan cooling and EMI available in each unit,

and has a capacity of up to 2-carrier/3-sector per a single L9CA. In addition to optic CPRI

with the L8HU, up to six optic ports per channel card are available.

The following table shows the key features and configurations of each board.

Board Quantity Description

UADB 1 Universal platform type A Digital Backplane board assembly

- UADU’s backboard

- Routing signals for traffic, control, clocks, power, etc.

UAMA 1 Universal platform type A Management board Assembly

- Main processor in the system

- Resource allocation/operation and maintenance

- Alarm collection and report to LSM

- Backhaul support (GE/FE)

- UADU FAN alarm handling

- Provides the interface for rectifier alarms

- Provides UDE (User Defined Ethernet) and UDA (User Defined Alarm)

- Generates and supplies GPS clocks (sync in & out)

L9CA Max. 3 LTE eNB Channel card board Assembly

- Call processing, resource allocation/operation and maintenance

- OFDMA/SC-FDMA Channel Processing

- Interface between the L8HU and optic CPRI

- Support for optic interface with CPRI RRH (E/O, O/E conversion in

CPRI Mux)

3-4 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

UAMA

The UAMA acts as a main processor of the UADU, and is responsible for network and

external interfacing, reset, and clock generation/distribution.

 Main Processor

The eNB’s main processor is a board acting in the topmost role of the eNB, and is

responsible for communication path setups between the UE and EPC, Ethernet

switching in the eNB, and system operation/maintenance. It also manages the status

for all hardware/software in the eNB, allocates and manages resources, collects alarms,

and reports all status information to the LSM.

 Network Interface

The UAMA directly interfaces with the EPC through the GE/FE and supports a total of

four ports (two optic and two copper ports). If only one type of port (either optic or

copper) is used, ports not in use can be other UDEs.

 External Interface

The UAMA provides the Ethernet interface for UDE in the UADU, and paths for

alarm information generated in external devices (additional devices supplied by the

provider) as well as reporting alarm information to the LSM.

 Reset

The UAMA provides the reset function for each board.

 Clock Generation and Distribution

By using the PP2S (even clock), digital 10 MHz signals received from the UCCM

(Universal Core Clock Module), the UAMA generates 10 MHz, even, and System

Fame Number (SFN) clocks for synchronization and distributes them to the hardware

blocks.

These clocks are used to maintain internal synchronization in the eNB and to operate

the system.

The UAMA also provides analog 10 MHz and 1 pps for measuring and relaying

equipments.

The UCCM transmits time information and location information through the TOD

(Time Of Day) path.

If the UCCM fails to receive GPS (Global Positioning System) signals due to an error

during system operation, it carries out the holdover function that supplies the normal

clocks that have been provided for a specific period of time.

L9CA

The L9CA is responsible for subscriber channel handling and CPRI interfacing.

 Subscriber Channel Processing Function

The L9CA modulates the packet data received from the upper processor and transmits

it to the RF part via CPRI. In the other direction, it demodulates the packet data

received from the RF, converts them to the format which is defined in the LTE

standard physical layer specifications, and transmits them to the upper processor.

 CPRI Interface

The L9CA interfaces via the L8HU and CPRI.

CHAPTER 3. LTE eNB Architecture

3.1.2 L8HU

The following shows the configuration of L8HU.

[Top View]

[Front View] [Bottom View]

Figure 3.4 L8HU Configuration

By default, the L8HU is installed outdoors for natural cooling.

The L8HU consists of a 2Tx/4Rx RF chain as an integrated RF unit with a transceiver,

power amplifier and filter installed in the single outdoor unit. It can support 10 MHz and

15 MHz bandwidth with firmware changes.

In the downlink path, the L8HU performs O/E conversion for the baseband signals received

from the UADU via the optic CPRI. The converted O/E signals are converted again into

analog signals by the DAC. The frequency of those analog signals is up converted through

the modulator and then those signals are amplified into high-power RF signals through the

power amplifier. The amplified signals are sent to the antenna through the filter part.

In the uplink path of the L8HU, the RF signals received through the filter part are amplified

low noise in the LNA (Low Noise Amplifier) and their frequency is then down-converted

through the demodulator. These down-converted frequency signals are converted to

baseband signals through the ADC. The signals converted into baseband are changed to

E/O through the CPRI and sent to the UADU. The control signals of the L8HU are

transmitted through the control path in the CPRI.

3-6 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

The main functions are as follows

Unit Description Configuration

L8HU LTE eNB remote radio Head Unit

- 700 MHz (DL 728~746 MHz, UL 698~716 MHz)

- Support for 5 MHz 2Tx4Rx per L8HU

- Support for 5 MHz 2-carrier/1-sector

- 20 + 20 W per carrier (40 W total)

- Up/Down RF conversion

- Low-noise amplifier

- RF high-power amplification

- Spurious wave suppression outside the bandwidth

- Includes E/O and O/E conversion modules for optic communications

with UADU.

- Support for RET (Remote Electrical Tilt)

Distributed type

CHAPTER 3. LTE eNB Architecture

3.1.3 Power supply

The following shows the configuration of the outdoor eNB’s power supply.

Smartpack

Rectifier

DC Distribution

Figure 3.5 Power Supply

Unit Quantity Description

DC Distribution 1 Divides the DC power from the rectifier to provide a supply to the

UADU, L8HU and additional devices.

Smartpack 1 Controls the rectifier and reports to the UAMA with alarms collected

by the I/O monitor.

Rectifier 3 Supplies DC power to the system. Up to three rectifiers can be

mounted.

3-8 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

The type of power supplied to the outdoor eNB and the connection points are shown in the

power diagram below.

SPD: Surge Protect Device

BATTERY

L8HU 2

L8HU 1

L8HU 0

DC5

DC4

AC 220 V

AC SPD

AC BOX

INPUT

OUTPUT AC 220 V

OUTLET/HEATER

Rectifier

DC Distribution

DC0

DC1

DC2

DC -48 V BATT

TERMINAL

HEATER

OUTLET

UADU

CSR

SPARE

DC3

Figure 3.6 Power Diagram

The input power (220 VAC) is directly supplied to the outlet and heater through the AC box,

and converted through the rectifier into DC -48 V. DC -48 V goes to the DC distribution,

and is distributed through the circuit breaker to the CSR, UADU, L8HU, etc.

CHAPTER 3. LTE eNB Architecture

3-10 © SAMSUNG Electronics Co., Ltd.

Smartpack

I/O monitor

FANM-C4

3.1.4 Environmental Devices

Mounted on the front door of the outdoor rack, FAN adjusts the system temperature by

discharging heated air in the rack outside.

If the system’s internal temperature is above the optimum, the smartpack and I/O monitor

control the FAN to decrease the temperature. If the system’s internal temperature reaches

the optimum, the smartpack and I/O monitor adjusts the FAN speed to control the

temperature.

Figure 3.7 Outdoor eNB’s Heat Discharge

LTE eNB System Description/Ver.1.0

The following table shows the outdoor eNB’s environmental devices.

Name Quantity Function

FAN 2 - Outdoor rack’s cooling fan

- Controls the fan according to the system’s internal temperature

detected through the sensor installed in the rack

 Room temperature mode: Low-speed operation

 High temperature mode: High-speed operation.

FANM-C4 1 Fan Module-C4

UADU’s cooling fan

SmartPack &

I/O monitor

1 - The built-in sensor detects the system temperature.

- Collects fire alarms

- Collects ‘door open’ alarms

- Collects flood alarms

- Collects ‘door fan’ alarms

- Reports collects alarms to the UAMA

Sensor 5 Sensors for temperature (2), flood (1), fire (1) and door (1)

UADU

A cooling fan is installed to keep the UADU shelf’s internal temperature optimal.

This allows the UADU to operate normally regardless of changes to the external temperature.

The UADU’s heat-discharge mechanism is shown below.

FANM-C4 Dust Filter

Figure 3.8 UADU Heat-Discharge Mechanism

L8HU

The L8HU is designed to discharge heat effectively through natural cooling without an

additional cooling device.

CHAPTER 3. LTE eNB Architecture

The following shows the outdoor eNB’s sensors.

Lamp

Fire sensor

Door sensor

Flood sensor

Temp sensor

Figure 3.9 Sensors

The smartpack and I/O monitor maintain/control the outdoor rack’s internal temperature,

and collect/report external environment alarms.

The smartpack and I/O monitor detects the rack’s internal temperature through the sensor

in the air outlet of the UADU to control the FAN speed. They are connected to the

environmental sensors (for temperature, flood, fire and door) installed in the rack to gather

environment data real-time, and report environment alarms to the LSM at the UAMA.

3-12 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

3.1.5 External Interface

External Interfaces of UADU

The following shows the interfaces of UADU.

CT RST DBG0 DBG1

L1 L2

L3 L4

-48 V

CT RST DBG0 DBG1

L1 L2

L3 L4 L5

PWR/ALM

PWR

RTN

UDA BH0 BH1 UDE0 UDE1 EDBG REC BH2

BH3

FANM-C4

CT GPS RST DBG

1PPS A10M GPS0 GPS1

Figure 3.10 UADU External Interface

Unit Interface Description

PWR RTN/-48 V Power Input (RTN/-48 V)

FANM-C4 PWR/ALM Fan Module-C4

UADU’s cooling fan

ACT CPU Active LED

GPS UCCM Status LED

RST Reset Switch (CPU Chip Reset)

DBG For the debugger (UART, RS-232)

UDA User Defined Alarm (Rx: 9 port, Tx: 2 port), Mini Champ

BH0, BH1 Copper Backhaul (1000Base-T), RJ-45

UDE0, UDE1 User Defined Ethernet (1000Base-T), RJ-45

EDBG For the debugger (10/100/1000Base-T), RJ-45

REC For the rectifier, RS-485

BH2, BH3 1000Base-LX or SX, RJ-45

1PPS Test Port 1PPS Output (from UCCM), SMA

A10M Test Port Analog 10 M Output (from UCCM), SMA

GPS 0 GPS ANT Input #0 (to UCCM), SMA

UAMA

GPS 1 GPS ANT Input #1 (to UCCM), SMA

ACT L9CA ACT LED

RST System reset

DBG0, DBG1 UART DSP Debug, USB

L0~5 L8HU IF (CPRI 4.0), Optic

L9CA

EDBG 10/100/1000 Base-T, RJ-45

Dust filter A/F Dust filter

CHAPTER 3. LTE eNB Architecture

L8HU External Interface

The following shows the external interfaces of L8HU.

TXMON0 TXMON1

Ground

TRX1 RX3TRX0

PWR

OPT 0/1

RET

RX2

[Bottom View]

Figure 3.11 L8HU External Interface

Interface Description

PWR DC -48 V power input port

Ground Frame Ground

OPT 0/1 Optic cable terminal connected to the UADU (cable gland)

RX2 RF receiving terminal #2

TXMON0 Tx signal monitoring terminal #0

TRX0 RF Tx/Rx terminal #0

RX3 RF receiving terminal #3

TXMON1 Tx signal monitoring terminal #1

TRX1 RF Tx/Rx terminal #1

RET AISG connector for remote electric tilting

3-14 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

3.2 Software Architecture

3.2.1 Basic Software Architecture

The LTE eNB software is divided into three parts, kernel space (OS/DD), forwarding space

(NPC and NP), and user space (MW, IPRS, CPS and OAM). Below is described each part.

Hardware

Forwarding Space

NPC NP

IPRS

IPSS

DHCP

CPS

ECMB

ECCB

SCTB

CSAB

GTPB

PDCB

RLCB

MACB

TM/TrM

SwM

SNMP

OSAB

CLI

Web-EMT

ENS MFS DUS

MDS THS HAS

Kernel Space

OS DD

DHCP

OAM

User Space

Figure 3.12 eNB Software Architecture

Operating System (OS)

The OS resets/controls hardware devices and allows the software on those devices to run.

It consists of the booter, kernel, root file system (RFS) and utility.

 Booter: A module that performs initialization on boards. It initializes the CPU, L1/L2

Cache, UART, and MAC and the devices such as CPLD and RAM within each board,

and runs the u-boot.

 Kernel: Manages the operation of multiple software processes and provides various

primitives to optimize the use of limited resources.

 RFS: Stores and manages the binary files, libraries, and configuration files necessary

for running and operating the software in accordance with the File-system Hierarchy

Standard (FHS) 2.2.

 Utility: Provides the functions for managing the CPLD (Complex Programmable

Logic Device), LED, watchdog, and environment and inventory information,

measuring and viewing the CPU load, and storing and managing fault information

when a processor goes down.

CHAPTER 3. LTE eNB Architecture

Device Driver (DD)

The device driver allows applications to operate normally on devices that are not directly

controlled from the OS in the system. It consists of a physical DD and virtual DD.

 Physical DD: Provides the interface through which an upper application can configure,

control, and monitor the external devices of the processor. (Switch DD and Ethernet

MAC driver, etc.)

 Virtual DD: Virtualizes the physical network interfaces in the kernel so that high-level

applications control the virtual interfaces, rather than the physical network interfaces

directly.

NPC (Network Processing Control)

The NPC creates/manages tables to process NP software packets and gathers/manages

network statistics and statuses by interfacing with high-level processes such as IPRS and

OAM.

Network Processing (NP)

The NP software processes packets necessary for backhaul interfacing.

The NP has the following features.

 Packet RX and TX

 IPv4 and IPv6

 Packet queuing and scheduling

 MAC filtering

 IP Packet forwarding

 IP fragmentation and reassembly

 Link aggregation

 VLAN termination

 ACL (Access Control List)

Middleware (MW)

The MW ensures seamless communication between OS and applications on various

hardware environments. It provides a message delivery service (MDS) between

applications, debugging utility service (DUS), event notification service (ENS), high

availability service (HAS) for redundancy management and data backup, task handling

service (THS).

 MDS: Provides all services related to message sending and receiving.

 DUS: Provides the function for transmitting debugging information and command

between the applications and the operator.

 ENS: Registers and manages various events such as timers, and provides the function

for sending an event message to the destination at the time when it is needed.

 HAS: Provides the data synchronization function and the redundancy state

management function.

3-16 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

 THS: Provides the task creation/termination function, the task control function, and

the function for providing task information, etc.

 Miscellaneous Function Service (MFS): The MFL is responsible for all hardware-

dependent functions, such as accessing physical addresses of hardware devices.

IP Routing Software (IPRS)

The IP routing software is responsible for IP routing and security for the eNB backhaul.

The IPRS consists of IPRS, IPSS (IP Security Software), DHCP (Dynamic Host

Configuration Protocol), each with the following features:

 IPRS: Collects and manages the system configuration and status information necessary

for IP routing. Based on this data, the IPRS provides the function for creating routing

information.

 Ethernet, VLAN-TE, link aggregation management

 Ethernet OAM

 IP address management

 IP routing information management

 QoS management

 IPSS: Software to perform the security function for the IP layer. It performs the

filtering function referring to IP address, TCP/UDP port number, and protocol type.

 DHCP: Software block to perform the automatic IP address allocation function.

The DHCP provides the function for obtaining an IP address automatically by

communicating with the DHCP server.

CHAPTER 3. LTE eNB Architecture

3.2.2 CPS Block

The CPS (Call Processing Software) block performs the resource management of the LTE

eNB and the call processing function in the eNB defined in the 3GPP and performs the

interface function with the EPC, UE, and adjacent eNBs. The CPS consists of the eNB

control processing subsystem (ECS) for network access and call control, and the eNB data

processing subsystem (EDS) for user traffic handling.

According to eNB specifications by the 3GPP, the ECS is composed of the SCTB, ECMB,

ECCB, SCTB and CSAB. The EDS is composed of GTPB, PDCB, RLCB and MACB.

The following shows the CPS architecture.

UAMA

GPRS

Packet

L9CA

Radio

Medium

CSAB

eNB Call

eNB

Stream

CPS

Figure 3.13 CPS Architecture

Stream Control Transmission protocol Block (SCTB)

The SCTB acts as the S1 interface between the eNB and the MME, and as the X2 interface

with the adjacent eNBs. It runs on the UAMA.

The SCTB has the following major functions:

 S1 interfacing

 X2 interfacing

eNB Common Management Block (ECMB)

The ECMB is responsible for call processing per eNB/cell, such as transmitting system

information and controlling the eNB overload. It runs on the UAMA.

The ECMB has the following major functions:

 Cell setting/release

 System information transmission

 eNB overload control

 Access barring control

 Resource measurement control

 Cell load information transmission

3-18 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

eNB Call Control Block (ECCB)

The ECCB is responsible for controlling a series of call processes between call setting and

release as well as for processing calls from the MME and neighbor eNB. It runs on the

UAMA.

The ECCB has the following major functions:

 Radio Resource Management

 Idle-Active status transition

 Bearer setting/change/release

 Paging

 MME selection and load balancing

 Call admission control

 Security

 Handover control

 UE measurement control

 Statistics processing

 SON-related call processing (mobility robustness and RACH optimization)

CPS SON Agent Block (CSAB)

The CSAB acts as a self-organizing network (SON) performed by the eNB CPS, and runs

on the UAMA.

The CSAB has the following major functions:

 Mobility robustness optimization

 RACH optimization

GPRS Tunneling Protocol Block (GTPB)

The GTPB is responsible for GTP handling as part of call processing in the eNB user plane,

and runs on the UAMA.

The GTPB has the following major functions:

 GTP tunnel control

 GTP management

 GTP data transmission

CHAPTER 3. LTE eNB Architecture

PDCP Block (PDCB)

The PDCB is responsible for PDCP handling as part of call processing in the eNB user

plane, and runs on the UAMA.

The PDCB has the following major functions:

 Header compression/decompression: ROHC only

 User and control plane data transmission

 PDCP sequence number maintenance

 DL/UL data forwarding during handover

 User and control data ciphering/deciphering

 Control data integrity protection

 Timer based PDCP SDU discard

Radio Link Control Block (RLCB)

The RLCB is responsible for RLC protocol handling as part of call processing in the eNB

user plane, and runs on the L9CA.

The RLCB has the following major functions:

 Higher-layer PDU transmission

 Automatic repeat request (ARQ) for AM mode data transmission

 RLC SDU concatenation, segmentation and reassembly

 Re-segmentation of RLC data PDUs

 In sequence delivery

 Duplicate detection

 RLC SDU discard

 RLC re-establishment

 Protocol error detection and recovery

Medium Access Control Block (MACB)

The MACB is responsible for MAC protocol handling as part of call processing in the eNB

user plane, and runs on the L9CA.

The MACB has the following major functions:

 Mapping between logical and transport channels

 Multiplexing & de-multiplexing

 HARQ

 Transport format selection

 Priority handling between UEs

 Priority handling between logical channels of one UE

3-20 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

3.2.3 OAM Blocks

The operation and maintenance (OAM) block is responsible for eNB operations and

maintenance.

The OAM consists of the OSAB, PM, FM, CM, SNMP, SwM, TM, TrM, Web-EMT and CLI.

The OAM has the following major functions:

OSAB (OAM SON Agent Block)

 Self-configuration and self-establishment of system information

 Automatic neighbor relation (ANR) optimization

 Energy saving management

Performance management (PM)

 Statistics collection

 Statistics storage

 Statistics transmission

Fault management (FM)

 Fault detection and alarm reporting

 Alarm view

 Alarm filtering

 Alarm severity setting

 Alarm threshold setting

 Alarm correlation

 Status management and reporting

 Status view

Configuration management (CM)

 System/cell addition/removal

 Configuration view/change/add/remove

 Call parameter view/change

 Neighbor view/change/add/remove

SNMP (Simple Network Management Protocol)

Interface with the SNMP Manager

CHAPTER 3. LTE eNB Architecture

3-22 © SAMSUNG Electronics Co., Ltd.

SwM (Software Management)

 Software and data file download/install

 Hardware unit and system reset

 Status monitoring of software units in operation

 Software and firmware information management/update

 Software upgrade

 Inventory management

Test management (TM)

 OCNS (Orthogonal Channel Noise Simulator) setting/release

 Model setting/release

 Ping test

 Tx/Rx output measurement

 Antenna VSWR (Voltage Standing Wave Ratio) measurement

Trace management (TrM)

Call trace

Web-EMT (Web-based Element Maintenance Terminal)

 Web server

 Operation with other OAM blocks for processing commands

Command Line Interface (CLI)

 CLI user management

 Command input and output display

 Fault/status message display

LTE eNB System Description

CHAPTER 4. Message Flows

4.1 Call-Processing Message Flows

This chapter describes message flow diagrams and functions for attach, service request,

detach and handover processes. The handover process includes the intra E-UTRAN

handover and inter-RAT (UTRAN) handover processes. The message flow diagram and

function of the CS fallback process as part of the inter RAT (UTRAN, GERAN) operation

are described below.

CHAPTER 4. Message Flows

Attach Process

The figure below shows the message flow of the Attach procedure.

UE eNB MME S-GW

EPC

Downlink data

1) Random Access Procedure

2) RRCConnectionRequest

3) RRCConnectionSetup

4) RRCConnectionSetupComplete

(Attach Request) 5) Initial UE Message

(Attach Request)

6) Authentication/NAS Security Setup

10) UECapabilityEnquiry

11) UECapabilityInformation

13) SecurityModeCommand

14) SecurityModeComplete

15) RRCConnectionReconfiguration

(Attach Accept)

18) ULInformationTransfer

(Attach Complete)

19) Uplink NAS Transport

17) Initial Context Setup

Response

(Attach Accept)

9) Initial Context Setup Request

7) Create Session Request

8) Create Session Response

20) Modify Bearer Request

21) Modify Bearer Response

Uplink data Uplink data

12) UE Capability Info Indication

16) RRCConnectionReconfiguration Complete

Figure 4.1 Attach Process

4-2 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Step Description

1 The UE runs the Random Access process (TS 36.321, 5.1) with the eNB.

2-4 The UE initializes the RRC Connection Establishment process (TS 36.331, 5.3.3).

The UE includes the ATTACH REQUEST message (NAS) in the

RRCConnectionSetupComplete message (PRC) and sends it to the eNB.

5 The eNB induces the MME from the RRC factors, includes the ATTCH REQUEST

message in the INITIAL UE message, which is an S1-MME Control message, and

sends it to the MME.

6 If there is no UE context in the network, the integrity of the ATTACH REQUEST

message is not protected, or the integrity check fails, then authentication and NAS

security setup are performed as a requisite. The UE runs the Evolved Packet System

(EPS) Authentication and Key Agreement (AKA) process (TS 33.401, 6.1.1) with the

MME. The MME establishes an NAS security association with the UE using the NAS

Security Mode Command (SMC) process (TS 33.401, 7.2.4.4).

7-8 The MME selects the P-GW and S-GW. The MME sends the Create Session Request

message to the S-GW. The S-GW adds an item to the EPS bearer table.

From this step and until it receives the Modify Bearer Request message of Step 20, the

S-GW stores the downlink packet received from the P-GW. The S-GW sends the Create

Session Response message back to the MME.

9 The MME includes the ATTACH REQUEST message in the INITIAL CONTEXT SETUP

REQUEST message, which is an S1-MME Control message, and sends it to the eNB.

This S1 message also includes the AS security context information on the UE, which

starts the RRC-level AS SMC process.

10-12 If the INITIAL CONTEXT SETUP REQUEST message doesn’t have UE Radio

Capability IE, the eNB starts the process to obtain UE Radio Capability from the UE,

and sends the results to the MME.

13-14 The eNB sends the Security Mode Command message to the UE, and the UE responds

with the SecurityModeComplete message. In the eNB, downlink encryption must start

after Security Mode Command is transmitted and the uplink decryption must start after

Security Mode Complete is received.

In the UE, the uplink encryption must be started after the SecurityModeComplete

message has been sent, and the downlink decryption must be started after the

SecurityModeCommand message has been received (TS 33.401, 7.2.4.5).

15-16 The eNB includes ATTACH ACCEPT in the RRC Connection Reconfiguration message

and sends it to the UE. The UE sends the RRC Connection Reconfiguration Complete

message to the eNB.

After receiving the ATTACH ACCEPT message, the UE can send uplink packets to the

S-GW and P-GW via the eNB.

17 The eNB sends the INITIAL CONTEXT SETUP RESPONSE message to the MME.

18-19 The UE sends the UL Information Transfer message containing the ATTACH

COMPLETE to the eNB. The eNB passes the UPLINK NAS TRANSPORT message

containing the ATTCH COMPLETE to the MME.

20-21 After receiving both of the INITIAL CONTEXT RESPONSE message at step 17 and the

ATTACH COMPLETE message at step 19, the MME sends the Modify Bearer Request

message to the S-GW.

The S-GW sends the Modify Bearer Response message to the MME, and then can

send the stored downlink packets.

CHAPTER 4. Message Flows

Service Request Initiated by the UE

The figure below shows the message flow of the Service Request procedure initiated by the

UE.

UE eNB MME S-GW

EPC

Downlink data

14) Modify Bearer Response

13) Modify Bearer Request

1) Random Access Procedure

2) RRCConnectionRequest

3) RRCConnectionSetup

4) RRCConnectionSetupComplete

(Service Request) 5) Initial Message

(Service Request)

6) Authentication/NAS Security Setup

8) SecurityModeCommand

9) SecurityModeComplete

10) RRCConnectionReconfiguration

11) RRCConnectionReconfiguration Complete

(Service Accept)

12) Initial Context Setup Response

(Service Accept)

7) Initial Context Setup Request

Uplink data Uplink data

Figure 4.2 Service Request Process by UE

4-4 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Step Description

1 The UE runs the Random Access process with the eNB.

2-4 The UE includes the SERIVCE REQUEST message, which is an NAS message, in the

RRC message that will be sent to the eNB, and sends it to the MME.

5 The eNB includes the SERVICE REQUEST message in the INITIAL UE message,

which is an S1-AP message, and passes it to the MME.

6 If there is no UE context for the UE in the network, the integrity is not protected for the

ATTACH REQUEST message, or the integrity check fails, an authentication and an

NAS security setup are always performed. The UE carries out the EPS AKA procedure

(TS 33.401, 6.1.1) with the MME. The MME establishes an NAS security association

with the UE using the NAS SMC process (TS 33.401, 7.2.4.4).

7 The MME sends the INITIAL CONTEXT SETUP REQUEST message, which is an S1-

AP message, to the eNB. This step activates radio and S1 bearers for all active EPS

bearers.

8-11 The eNB sets up the RRC radio bearers. The user plane security is established at this

step. The uplink data from the UE can now be passed by the eNB to the S-GW.

The eNB sends the uplink data to the S-GW, which, in turn, passes it to the P-GW.

12 The eNB sends the INITIAL CONTEXT SETUP RESPONSE message, which is an S1-

AP message, to the MME.

13-14 The MME sends the Modify Bearer Request message per PDN connection to the S-GW.

The S-GW can now send the downlink data to the UE, and sends Modify Bearer

Response to the MME.

Service Request by Networking

The message flow diagram below shows the Service Request process by networking.

UE eNB

EPC

3) PAGING Acknowled

1) Downlink Data Notification

S-GW MME

2) Downlink Data Notification

4) Paging

5) UE triggered Service Request procedure

Figure 4.3 Service Request Process by Networking

CHAPTER 4. Message Flows

Step Description

1-2 When the S-GW receives downlink data packets for a UE whose user plane is not

connected, it sends the Downlink Data Notification message to the MME which has the

control plane connection with the UE. The MME replies to the S-GW with the Downlink

Data Notification Acknowledge message. The S-GW stores additional downlink data

packets for the UE when it receives them. In this case, it does not send a new Downlink

Data Notification message.

3-4 When the UE is registered to the MME, the MME sends the PAGING message to all

eNBs that belong to the trace area where the UE is registered. When the eNB receives

the PAGING message from the MME, the eNB sends the Paging message to the UE.

5 When the UE in Idle mode receives the PAGING message via the E-UTRAN

connection, the Service Request procedure initiated by the UE is started. The S-GW

sends the downlink data to the UE via the RAT which has performed the Service

Request procedure.

Detach Initiated by the UE

The figure below shows the message flow of the Detach procedure initiated by the UE.

9) UE Context Release Complete

UE eNB MME S-GW

5) Downlink NAS Transport

(Detach Accept)

(Detach)

8) RRCConnectionRelease

(Detach Accept)

6) DLInformationTransfer

7) UE Context Release Command

3) Delete Session Request

2) Uplink NAS Transport

(Detach Request)

4) Delete Session Response

1) ULInformationTransfer

EPC

Figure 4.4 Detach Process by UE

4-6 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

Step Description

1-2 The UE sends the DETACH REQUEST message, which is an NAS message, to the

MME. This NAS message is used to start setting up an S1 connection when the UE is in

Idle mode.

3 The active EPS bearers and their context information for the UE and MME which are in

the S-GW are deactivated when the MME sends the Delete Session Request message

for each PDN connection.

4 When receiving the Delete Session Request message from the MME, the S-GW

releases the related EPS bearer context information and replies with the Delete Session

Response message.

5-6 If the detach procedure has been triggered due to other reason except for the case that

the power of the UE was turned off, the MME sends the DETACH ACCEPT message to

the UE.

7 The MME sets the Cause IE value of the UE CONTEXT RELEASE COMMAND

message to ‘Detach’ and sends this message to the eNB to release the S1-MME

signaling connection to the UE.

8 If the RRC connection has not yet been released, the eNB sends the

RRCConnectionRelease message to the UE in Requested Reply mode. Once a reply to

this message is received from the UE, the eNB removes the UE context.

9 The eNB returns the UE CONTEXT RELEASE COMPLETE message to the MME to

confirm the S1 release. This releases the signaling connection between the MME and

ENB for the UE. This step must be performed immediately following step 7.

CHAPTER 4. Message Flows

Detach Initiated by the MME

The figure below shows the message flow of the Detach procedure initiated by the MME.

UE eNB MME S-GW

3) Delete Session Request

6) UPLINK NAS TRANSPORT

(Detach Accept)

9) UE Context Release Complete

4) Delete Session Response

1) DOWNLINK NAS TRANSPORT

(DETACH REQUEST)

7) UE Context Release Command

(Detach)

2) DLInformationTransfer

(Detach Request)

8) RRCConnectionRelease

5) ULInformationTransfer

(Detach Accept)

EPC

Figure 4.5 Detach Process by MME

Step Description

1-2 The MME detaches the UE implicitly if there is no communication between them for a

long time.

In case of the implicit detach, the MME does not send the DETACH REQUEST

message to the UE. If the UE is in the connected status, the MME sends the DETACH

REQUEST message to the UE to detach it explicitly.

3-4 These steps are the same as Step 3 and 4 in ‘Detach Procedure by UE’.

5-6 When the UE receives the DETACH REQUEST message from the MME in Step2, the

UE sends the DETACH ACCEPT message to the MME. The eNB transmits this NAS

message to the MME.

7 After receiving both of the DETACH ACCEPT message and the Delete Session

Response message, the MME sets the Cause IE value of the UE CONTEXT RELEASE

COMMAND message to ‘Detach’ and sends this message to the eNB to release the S1

connection to the UE.

8-9 These steps are the same as Step 8 and 9 in ‘Detach Procedure by UE’.

4-8 © SAMSUNG Electronics Co., Ltd.

LTE eNB System Description/Ver.1.0

LTE Handover-X2-based Handover

The figure below shows the message flow of the X2-based Handover procedure.

UE Source eNB MME S-GW

EPC

1) MeasurementReport

Down/Uplink data Down/Uplink data

3) Handover Request Acknowledge

5) SN Status Transfer

4) RRCConnection-

Reconfiguration

(mobilityControlinfo)

Data forwarding

)

nchronization/UL allocation and timin

7) RRCConnectionReconfigurationComplete

Forwarded data

Uplink data

Forwarded data

Downlink data

Uplink data

Downlink data

8) Path Switch Request 9) Modify Bearer Request

End marker

10) Modify Bearer Response

12) UE Context Release

2) Handover Request

Request

Acknowledge

11) Path Switch

Target eNB

Downlink/Uplink data

Figure 4.6 X2-based Handover Process

CHAPTER 4. Message Flows

Step Description

1 The UE sends the Measurement Report message according to the system information,

standards and rules.

The UE sends the Measurement Report message according to the system information,

standards and rules.

2 The source eNB sends the target eNB a HANDOVER REQUEST message containing

the information required for handover. The target eNB can perform management control

in accordance with the received E-RAB QoS information.

3-4 The target eNB prepares the handover and creates an RRCConnectionReconfiguration

message, containing the mobileControlInfo IE that tells the source eNB to perform the

handover. The target eNB includes the RRCConnectionReconfiguration message in the

HANDOVER REQUEST ACKNOWLEDGE message, and sends it to the source eNB.

The source eNB sends the UE an RRCConnectionReconfiguration message, containing

the needed parameter values to command it to perform the handover.

5 To send the uplink PDCP SN receiver status and the downlink PDCP SN transmitter

status of the E-RABs of which the PDCP status must be preserved, the source eNB

sends the SN STATUS TRANSFER message to the target eNB.

6 After receiving the RRCConnectionReconfiguration message containing

mobileControlInfo IE, the UE performs synchronization with the target eNB and

connects to the target cell via a Random Access Channel (RACH). The target eNB

replies with an allocated UL and a timing advance value.

7 After having connected to the target cell successfully, the UE notifies the target eNB that

the Handover procedure has been completed using an RRCConnection-

ReconfigurationComplete message.

8 The target eNB, using the PATH SWITCH REQUEST message, notifies the MME that

the UE has changed the cell.

9-10 The MME sends the Modify Bearer Request message to the S-GW. The S-GW changes

the downlink data path into the target eNB. The S-GW sends at least one ‘end marker’

to the source eNB through the previous path, and releases the user plane resources for

the source eNB.

The S-GW sends a Modify Bearer Response message to the MME.

11 The MME sends the PATH SWITCH REQUEST ACKNOWLEDGE message to

acknowledge the PATH SWITCH REQUEST message.

12 The target eNB sends the UE CONTEXT RELEASE message to the source eNB to

notify the handover has succeeded and to make the source eNB release its resources.

When receiving the UE CONTEXT RELEASE messages, the source eNB released the

radio resource and the control plane resource related to the UE context.

LTE eNB System Description/Ver.1.0

LTE Handover-S1-based Handover

The figure below shows the message flow of the S1-based Handover procedure.

UE Source eNB MME S-GW

EPC

Target eNB

Downlink/Uplink data Downlink/Uplink data

3) Handover Request

5) Create Indirect Data

Forwarding Tunnel Request

17) UE Context Release Command

18) UE Context Release Complete 19) Delete Indirect Data

Forwarding Tunnel Request

20) Delete Indirect Data

Forwarding Tunnel Response

Downlink/Uplink data Downlink/Uplink data

)

Trackin

Area U

date

rocedure

8) RRCConnection-

Reconfiguration

(mobilityControlinfo)

1) Direct data forwarding

)

Decision to tri

er a relocation via

2) Handover Required

Indirect data forwarding

Downlink data

15) Modify Bearer Response

6) Create Indirect Data

Forwarding Tunnel Response

7) Handover Command

9) eNB Status Transfer

10) MME Status Transfer

2) Indirect data forwarding

)

Detach from old cell/S

nchronize to new cell

12) RRCConnectionReconfigurationComplete

Forwarded data

Uplink data Uplink data

13) Handover Notify 14) Modify Bearer Request

4) Handover Request

Acknowledge

End marker

Forwarded data

End marker

Figure 4.7 S1-based Handover Process

CHAPTER 4. Message Flows

Step Description

1 The source eNB determines whether to perform S1-based handover into the target eNB.

The source eNB can make this decision when there is no X2 connection to the target or

when an error is notified by the target eNB after an X2-based handover has failed, or

based on the information the source eNB has obtained dynamically.

2 The source eNB sends the HANDOVER REQUIRED message to the MME. The source eNB

notifies the target eNB which bearer is used for data forwarding and whether forwarding

can be made directly from the source eNB to the target eNB.

3-4 The MME sends the HANDVER REQUEST message to the target eNB. This message

makes the target eNB to create a UE context containing the bearer-related information

and the security context.

The target eNB sends the HANDOVER REQUEST ACKNOWLEDGE message to the

MME.

5-6 If indirect forwarding is used, the MME sends the Create Indirect Data Forwarding

Tunnel Request message to the S-GW. The S-GW replies the MME with the Create

Indirect Data Forwarding Tunnel Response message.

7-8 The MME sends the HANDOVER COMMAND message to the source eNB. The source

eNB creates the RRCConnectionReconfiguration message using the Target to Source

Transparent Container IE value contained in the HANDOVER COMMAND message and

then sends it to the UE.

9-10 To send the PDCP status, and the HFN status of the E-RABs of which the PDCP status

must be preserved, the source eNB sends the eNB/MME STATUS TRANSFER message

to the target eNB via the MME. The source eNB must start forwarding the downlink data

to the target eNB through the bearer which was determined to be used for data

forwarding. This can be either direct or indirect forwarding.

11 The UE performs synchronization with the target eNB and connects to the target cell via

a RACH.

The target eNB replies with an allocated UL and a timing advance value.

12 After having synchronized with the target cell, the UE notifies the target eNB that the

Handover procedure has been completed using the

RRCConnectionReconfigurationComplete message. The downlink packets forwarded

from the source eNB cab be sent to the UE.

The uplink packets can be also sent from the UE to the S-GW via the target eNB.

13 The target eNB sends the HANDOVER NOTIFY message to the MME. The MME starts

the timer which tells when the resources of the source eNB and the temporary resources

used by the S-GW for indirect forwarding will be released.

14 For each PDN connection, the MME sends the Modify Bearer Request message to the

S-GW. Downlink packets are sent from the S-GW to the target eNB immediately.

15 The S-GW sends the Modify Bearer Response message to the MME. As soon as the

target eNB changes the path to help packet reordering, the S-GW sends at least one

‘end marker’ packet to the source eNB through the previous path.

16 If any of the conditions listed in section 5.3.3.0 of TS 23.401 (6) are met, the UE starts

the Tracking Area Update procedure.

LTE eNB System Description/Ver.1.0

(Continued)

Step Description

17-18 When the timer started at step 13 expires, the MME sends the UE CONTEXT RELEASE

COMMAND message to the source eNB. The source eNB releases the resources

related to the UE and replies to the target eNB with the UE CONTEXT RELEASE

COMPLETE message.

19-20 If indirect forwarding has been used, when the timer started at step 13 expires the MME

sends the Delete Indirect Data Forwarding Tunnel Request message to the S-GW.

This message gets the S-GW to release the temporary resources allocated for indirect

forwarding at step 5.

The S-GW replies to the MME with the Delete Indirect Data Forwarding Tunnel

Response message.

CHAPTER 4. Message Flows

Inter-RAT Handover-LTE to UTRAN PS Handover

Below is the message flow for the PS handover procedure from the E-UTRAN to the

UTRAN.

Figure 4.8 E-UTRAN-UTRAN PS Handover Process

Step Description

1 The source eNB determines the PS handover to the UTRAN. This handover can be

determined in accordance with the measurement report received from UE.

2 The source eNB sends the HANDOVER REQUIRED message to the MME. The source

eNB then puts the Source RNC to Target RNC Transparent Container IE information

into the message to transmit the information to the target RNC.

Downlink/Uplink data Downlink/Uplink data

1) Handover Initiation

2) Handover Required

3) Forward Relocation Request

4) Create Session

Request/Response

5) Relocation Request

6) Relocation Request Acknowledge

7) Create Indirect Data

Forwarding Tunnel

Request/Response

8) Forward Relocation Response

9) Create Indirect Data

10) Handover Command

E-UTRAN Command

11) Mobility From Indirect data forwarding

Indirect data forwarding

12) HO to UTRAN Complete 13) Relocation Complete

14) Forward Relocation Complete

Notification

15) Forward Relocation Complete

Acknowledge

17) Modify Bearer

Request/Response

18) Modify Bearer

Response Downlink/Uplink data

Downlink/Uplink data

19) Routing Area Update procedure

20) S1 Release

Request/Response

21) Delete Session

22) Create Indirect Data

Forwarding Tunnel

Request/Response

23) Create Indirect Data

Forwarding Tunnel

Downlink/Uplink data

Forwarding Tunnel

Request/Response

16) Modify Bearer

uest

Request/Response

P-GW Target S-GW Target SGSN Source MME Source S-GW Target RNS Source eNB UE

LTE eNB System Description/Ver.1.0

(Continued)

Step Description

3-4 The source MME recognizes the handover from the target ID IE of the HANDVER

REQUIRED message to the UTRAN and sends the FORWARD RELOCATION

REQUEST message to the target SGSN. The target SGSN determines whether to

change the S-GW. Then if change is required, it carries out the Create Session

Request/Response procedure with a new S-GW.

5-6 The target SGSN transmits the RELOCATION REQUEST message to the target RNC

to request resource allocation for the target RNC. The target RNC carries out the CAC

and resource allocation for each RAB for which handover is requested, and transmits

the RELOCATION REQUEST ACKNOWLEDGE message containing the result to the

target SGSN to respond to the request. The Target RNC to Source RNC Transparent

Container IE to transmit to the source eNB is then contained.

7-9 To perform the forwarding tunnel setup, the target SGSN carries out the Create Indirect

Data Forwarding Tunnel Request/Response procedure with target S-GW and transmits

the FORWARD RELOCATION RESPONSE message to the source MME. To perform

the forwarding tunnel setup, the source MME carries out the Create Indirect Data

Forwarding Tunnel Request/Response procedure with the source S-GW.

10-11 The source MME sends the HANDOVER COMMAND message to the source eNB. By

doing so, the handover preparation procedure to the target UTRAN is completed.

The Source eNB configures the MOBILITY FROM E-UTRAN COMMAND containing the

Target RNC to Source RNC Transparent Container IE in the HANDOVER COMMAND

message and transmits it to the UE to request the PS handover to the UTRAN.

12 The UE performs synchronization with the target UTRAN and connects to the target cell

via a RACH.

After UE is successfully connected to the target cell, UE transmits the HANDOVER TO

UTRAN COMPLETE message to the target UTRAN to complete the handover

procedure.

13-15 The target RNC transmits the RELOCATION COMPLETE message to the target SGSN

to notify that the handover procedure from the UE to the UTRAN has been completed

successfully.

The target SGSN transmits the FORWARD RELOCATION COMPLETE NOTIFICATION

message to the source MME. At this time, the source MME operates the waiting timer

for releasing the resource of the E-UTRAN and transmits the FORWARD RELOCATION

COMPLETE ACKNOWLEDGE response message to the target SGSN. The target

SGSN operates the waiting timer for releasing the forwarding tunnel at the time when

the source MME receives the response message.

16-18 For each PDN connection, the target SGSN sends the Modify Bearer Request message

to the target S-GW. The downlink packet is then transmitted from the S-GW to the target

RNC. The target S-GW

carries out the Modify Bearer Request/Response procedure with the P-GW and

transmits the Modify Bearer Response message to the target SGSN.

19 When UE satisfies the conditions specified in section 5.5.2.1 of TS 23.401, the Routing

Area Update procedure starts.

20-23 When the timer of procedure 14 has expired, the source MME requests the resource

release procedure to be carried out on the source eNB and the source S-GW.

When the timer of procedure 15 has expired, the target SGSN carries out the resource

release allocated for the forwarding tunnel with the target S-GW.

CHAPTER 4. Message Flows

Inter-RAT Handover-UTRAN to LTE PS Handover

Below is the message flow for the PS handover procedure from the UTRAN to the E-

UTRAN.

11) HO from UTRAN

UE Source RNC

Downlink/Uplink data

Target eNB Source SGSN Source S-GW Target MME Target S-GW P-GW

Downlink/Uplink data Downlink/Uplink data

1) Handover Initiation

2) Relocation Required

3) Forward Relocation Request

4) Create Session

Request/Response

5) Handover Request

6) Handover Request Acknowledge

7) Create Indirect Data

Forwarding Tunnel

Request/Response

8) Forward Relocation Response

Forwarding Tunnel

Request/Response

9) Create Indirect Data

10) Relocation Command

Command Indirect data forwarding

Indirect data forwarding

12) RRC Connection Reconfiguration Complete

13) Handover Notify

14) Forward Relocation Complete

Notification

15) Forward Relocation Complete

Acknowledge 17) Modify Bearer

Request/Response

18) Modify Bearer

Response Downlink/Uplink data Downlink/Uplink data Downlink/Uplink data

19) Tracking Area Update procedure

20) Iu Release

21) Delete Session

Request/Response

22) Delete Indirect Data

Forwarding Tunnel

Request/Response 23) Delete Indirect Data

Forwarding Tunnel

Request/Response

16) Modify Bearer

Request

Figure 4.9 UTRAN-E-UTRAN PS Handover Process

Step Description

1 The source RNC determines the PS handover to the E-UTRAN. This handover can be

determined in accordance with the measurement report received from UE.

2 The source RNC sends the RELOCATION REQUIRED message to the SGSN.

The source RNC then puts the Source eNB to Target eNB Transparent Container IE

information into the message to transmit the information to the target eNB.

LTE eNB System Description/Ver.1.0

(Continued)

Step Description

3-4 The source SGSN recognizes the handover from the target ID IE of the RELOCATION

REQUIRED message to the E-UTRAN and sends the FORWARD RELOCATION

REQUEST message to the target MME. The target MME determines whether to change

the S-GW, if change is required, it carries out the Create Session Request/Response

procedure with a new S-GW.

5-6 The target MME transmits the HANDOVER REQUEST message to the target eNB to

request resource allocation for the target eNB. The target eNB carries out the CAC and

resource allocation for each RAB for which handover is requested, and transmits the

HANDOVER REQUEST ACKNOWLEDGE message containing the result to the target

MME to respond to the request. At this time, the Target eNB to Source eNB Transparent

Container IE to transmit to the source RNC is contained.

7-9 To perform the forwarding tunnel setup, the target MME carries out the Create Indirect

Data Forwarding Tunnel Request/Response procedure with target S-GW and transmits

the FORWARD RELOCATION RESPONSE message to the source SGSN. To perform

the forwarding tunnel setup, the source SGSN carries out the Create Indirect Data

Forwarding Tunnel Request/Response procedure with the source S-GW.

10-11 The source SGSN sends the RELOCATION COMMAND message to the source RNC.

By doing so, the handover preparation procedure to the target E-UTRAN is completed.

The source RNC configures the Handover FROM UTRAN COMMAND message

containing the Target eNB to Source eNB Transparent Container IE in the

RELOCATION COMMAND message and transmits it to UE to request the PS handover

to the E-UTRAN.

12 The UE performs synchronization with the target E-UTRAN and connects to the target

cell via a RACH.

After UE is successfully connected to the target cell, UE transmits the RRC

CONNECTION RECONFIGURATION COMPLETE message to the target E-UTRAN to

complete the handover procedure.

13-15 The target eNB then transmits the HANDOVER NOTIFY message to the target MME

to notify that the handover procedure to the E-UTRAN has been completed

successfully. The target MME transmits the FORWARD RELOCATION COMPLETE

NOTIFICATION message to the source SGSN. At this time, the source SGSN operates

the waiting timer for releasing the resource of the UTRAN and transmits the FORWARD

RELOCATION COMPLETE ACKNOWLEDGE response message to the target MME.

The target MME operates the waiting timer for releasing the forwarding tunnel at the

time when the source SGSN receives the response message.

16-18 For each PDN connection, the target MME sends the Modify Bearer Request message

to the target S-GW. The downlink packet is then transmitted from the S-GW to the target

eNB. The target S-GW carries out the Modify Bearer Request/Response procedure with

the P-GW and transmits the Modify Bearer Response message to the target MME.

19 When UE satisfies the conditions specified in section 5.5.2.2 of TS 23.401, the Tracking

Area Update procedure starts.

20-23 When the timer of procedure 14 has expired, the source SGSN requests the resource

release procedure to be carried out on the source RNC and the source S-GW.

When the timer of procedure 15 has expired, the target MME carries out the resource

release allocated for the forwarding tunnel with the target S-GW.

CHAPTER 4. Message Flows

CS Fallback to UTRAN

Below is the message flow for the CS Fallback process from the E-UTRAN to the UTRAN.

The procedure below shows that the CS Fallback process is carried out through redirection

processing to the UTRAN without PS HO when UE, which is in RRC Connected status,

sends the CS call.

Figure 4.10 CS Fallback to UTRAN Process (UE in Active Mode, No PS HO Support)

Step Description

1 When an RRC Connected UE in the E-UTRAN requests a CS call, it creates an EXTENDED

SERVICE REQUEST message (NAS) containing the CS fallback indicator, and sends it

to the network. The UE uses an RRC UL INFORMATION TRANSFER message.

The eNB sends this to the MME using a UL NAS TRANSPORT message.

2-3 The MME prepares an S1AP message (UE CONTEXT MODIFICATION REQUEST)

containing the CS fallback indicator, and sends it to the eNB to request CS fallback

handling.

The eNB transmits a response message (UE CONTEXT MODIFICATION RESPONSE)

appropriate for Process 2 to the MME.

4 The eNB can instruct the UE to measure the target RAT if it needs the UE’s

measurement for CS fallback handling (optional).

5 The eNB uses a redirection process for a CS fallback to UTRAN.

The eNB includes redirected carrier information on the target UTRAN in the RRC

CONNECTION RELEASE message to send to the UE. The UE redirects to the UTRAN

based on the redirected carrier information instructed by the eNB.

6 The eNB transmits the UE CONTEXT RELEASE REQUEST message to the MME.

7 The MME carries out the procedure for releasing the UE context of the E-UTRAN.

SGSN MSC S/P-GW MME Target RNS

Downlink/U

link data Downlink/Uplink data

4) UE Measurement

Solicitation (Optional)

2) S1AP Request Message

3) S1AP Response Message

1) UL Information Transfer/UL NAS Transport

6) UE Context Release Request

Release

5) RRC Connection

8) UE changes RAT then LAU or Combined RA/LA update or RAU or LAU and RAU

(Extended Service Request)

With CS Fallback indicator

7) S1 Release

9) Update bearer (s)

10) RRC/Iu-CS messages

(CM Service Request)

CS Call Setup

Source eNB UE

LTE eNB System Description/Ver.1.0

(Continued)

Step Description

8 After connecting to the UTRAN, UE transmits the RRC INITIAL DIRECT TRANSFER

message to set the CS signaling connection. If the LA or RA of the connected UTRAN

cell is different from the stored information, the location registration procedure (LAU

and/or RAU or combined LAU/RAU) is carried out.

9 After receiving the UE CONTEXT RELEASE REQUEST message in Procedure 6, the

MME carries out the suspension processing of the non-GBR bearer (s) of the S-GW/P-

GW and the deactivation processing of the GBR bearer (s).

Afterward, the MME manages the UE context in the suspended status.

10 The UE transmits the CM SERVICE REQUEST message to the UTRAN to carry out

next procedure for the CS call setup.

CS Fallback to GERAN

Below is the message flow for the CS Fallback procedure from the E-UTRAN to the

GERAN. The procedure below shows that the CS Fallback procedure is carried out through

Cell Change Order processing to the GERAN without PS HO when a UE which is in the

RRC_Connected status sends the CS call.

Figure 4.11 CS Fallback to GERAN Process (UE in Active Mode, No PS HO Support)

Source eNB

Downlink/Uplink data

Target BSS MME S/P-GW MSC

Downlink/Uplink data

4) UE Measurement

Solicitation (Optional)

2) S1AP Request Message

3) S1AP Response Message

1) UL Information Transfer/UL NAS Transport

6) UE Context Release Request

UTRA Command

5) Mobility from E-

8) UE changes RAT then LAU or Combined RA/LA update or RAU or LAU and RAU

(Extended Service Request)

With CS Fallback Indicator

7) S1 Release

11) Update bearer (s)

12) RRC/Iu-CS messages

(CM Service Request)

CS Call Setup

10) Suspend Request/Response

9) Suspend

SGSN

CHAPTER 4. Message Flows

Step Description

1 When an RRC Connected UE in the E-UTRAN requests a CS call, it creates an

EXTENDED SERVICE REQUEST message (NAS) containing the CS fallback indicator,

and sends it to the network. The UE uses an RRC UL INFORMATION TRANSFER

message.

The eNB sends this to the MME using a UL NAS TRANSPORT message.

2-3 The MME prepares an S1AP message (UE CONTEXT MODIFICATION REQUEST)

containing the CS fallback indicator, and sends it to the eNB to request CS fallback

handling.

The eNB transmits a response message (UE CONTEXT MODIFICATION RESPONSE)

appropriate for Process 2 to the MME.

4 The eNB can instruct the UE to measure the target RAT if it needs the UE’s

measurement for CS fallback handling (optional).

5 The eNB uses the Cell Change Order procedure for the CS Fallback processing to the

GERAN.

The eNB transmits the MOBILITY FROM E-UTRA COMMAND message containing the

PCI and carrierFreq which is applicable to the GERAN target cell to the UE.

The UE carries out the cell change order procedure on the GERAN target cell specified

by the eNB.

6 The eNB transmits the UE CONTEXT RELEASE REQUEST message to the MME.

7 The MME carries out the procedure for releasing the UE context of the E-UTRAN.

8 After connecting to the GERAN, the UE carries out the RR connection setup procedure.

If the LA or RA of the connected GERAN cell is different from the stored information, the

location registration procedure (LAU and/or RAU or combined LAU/RAU) is carried out.

9-10 When the UE or the target GERAN cell does not support the Dual Transfer Mode

(DTM), the UE starts the Suspend procedure. When the Suspend request is received

from the UE, the SGSN processes the Suspend Request/Response procedure with the

MME.

11 The MME carries out the suspension processing for the non-GBR bearer (s) of the S-

GW/P-GW and the deactivation processing of the GBR bearer (s). Afterward, the MME

manages the UE context in the suspended status.

12 The UE transmits the CM SERVICE REQUEST message to the UTRAN to carry out

next procedure for the CS call setup.

LTE eNB System Description/Ver.1.0

4.2 Data Message Flow

Sending Path

The user data received from the EPC is transmitted to the eNB UADU through the Ethernet

switch after passing the network interface module. The transmitted user data goes through

baseband-level digital processing before being configured for the CPRI, and then E/O

converted. The converted signal is transmitted to the L8HU that is located remotely

through an optic cable. L8HU operates the O/E conversion on the transmitted optic signal.

The converted baseband signal from the broadband is converted into an analog signal and

sent through the high-power amplifier, filter and antenna.

Receiving Path

The RF signal received by the antenna goes through the L8HU filter and low-noise

amplification by the LNA.

This signal is then converted into a baseband signal after RF down-conversion and digital

down-conversion. It is configured for the CPRI, and goes through E/O conversion again.

The converted signal is transmitted to the UADU that is located remotely through an optic

cable. The data for which the SC-FDMA signal processing is carried out in the UADU is

converted to the Gigabit Ethernet frame and transmitted from the UADU to the EPC via the

GE/FE.

L8HU

Figure 4.12 eNB System Control and Traffic Flow

Main

Processor

Channel

Card

Con

ver

sion

E/O

O/E

GE/FE

UADU

Optic CPRI

E/O

O/E

A/D

D/A

Con

ver

sion

DOWN

Conversion

LNA

Power

Amp

Filte

EPC

CHAPTER 4. Message Flows

4.3 Network Synchronization Flow

The eNB uses GPS to synchronize the system. The UCCM is a GPS receiving module in

the UADU, and receives synchronization signals from the GPS to generate/distribute clocks.

SYS (System Clock 30.72 MHz) UADU

SFN (System Frame Number)

PP2S (Even Clock)

Control

Figure 4.13 eNB Network Synchronization Flow

Clock

Generation & Distribution UCCM

1 pps Analog 10 MHz

Test equipment

Digital 10 MHz GPS

PP2S (Even Clock)

LTE eNB System Description/Ver.1.0

4.4 Alarm Signal Flow

An environmental fault or hardware mount/dismount is reported with an alarm signal,

which is collected by the UAMA of the UADU, and then reported to the LTE system

manager (LSM). The user can provide custom alarms through the UDA and environmental

alarms (flood, door, fire, temperature, etc.) through the ECM, and control the FAN in the rack.

The following alarms are collected by the UAMA:

Alarm Type Description Target to Apply

Function Fail Alarm Fault alarm due to software/hardware problems defined

as ‘function fail’

L9CA, UAMA

Power Fail Alarm Fault alarm due to power problems L9CA, UAMA

Deletion Alarm System report alarm due to hardware mount/dismount L9CA

Environmental Fault

Alarm

Alarms for the rectifier, flood, fire, FANM-B2, door,

control, etc.

System

UDA Custom Alarm by the operator UAMA

Figure 4.14 eNB System Alarm Flow

UAMA

L9CA

GPS Module (in UAMA)

ECM

L8HU #120

L8HU #0

: Reset

: Alarm

: Remote Pattern Reset

LSM

CHAPTER 4. Message Flows

4.5 Loading Flow

Loading is a process that downloads, from the LSM, software executables, data, etc.

required by the eNB’s processors and devices to operate.

The eNB’s loading is run during system initialization. Loading can also be run when a

board is mounted on the system, hardware is reset, or the high-level system operator

restarts a board.

On the first system initialization, the eNB is loaded through the LSM. As the loading

information is stored in the internal storage, no unnecessary loading is carried out afterward.

When comparing versions after initialization, if the information stored in the internal

storage is the latest information, remote loading is not carried out.

The loading information contains the software image and default configuration information

file, etc.

eNB

Figure 4.15 Loading Signal Flow

UAMA

Sub-processor

LSM

LTE eNB System Description/Ver.1.0

4.6 Operation and Maintenance Message Flow

The operator can view/change the eNB status through the system manager. To do this, the

eNB has an SNMP agent through which the LSM operator can run eNB operations and

maintenance remotely. The operator can also perform Web-EMT-based maintenance

activities using the web browser in the console terminal or through the CLI using

telnet/SSH access.

The statistical information provided by the eNB is given to the operator in accordance with

the collection interval.

Operation and Maintenance Message Flow

The eNB operation and maintenance occur through SNMP messages between the SNMP

agent in the main OAM and the LSM’s SNMP manager.

The eNB processes various messages from the LTE’s SNMP manager, and reports the

results back to the manager as well as reporting real time if events such faults or status

changes occur. The operation and maintenance signal flow is shown below.

Web-EMT (HTTP Client)/CLI LSM (SNMP Manager)

eNB

UAMA

HTTP Server

CLI SNMP

Other Block

SNMP message

HTTP message (command/response)

CLI command

Statistical Data

Figure 4.16 Operation and Maintenance Signal Flow

CHAPTER 4. Message Flows

This page is intentionally left blank.

LTE eNB System Description

CHAPTER 5. Supplementary

Functions and Tools

5.1 Web-EMT

The Web-EMT is a GUI-based console terminal and tool for device-monitoring, operation,

and maintenance through direct access to the eNB. The operator can run the Web-EMT

using Internet Explorer, without installing additional software. The GUI is provided using

the HTTPs protocol internally.

Figure 5.1 Web-EMT Interface

The operator can use the Web-EMT to restart the eNB or internal boards, view/set

configuration and operation parameters, monitor statuses and faults, and run a diagnosis.

However, increasing/decreasing resources or changing operational information on neighbor

lists is possible only through the LSM which manages the entire network and loaded image.

eNB

UAMA

HTTP Server

Other Block

OAM

command/

response

eNB

HTTP message HTTP message

UAMA

HTTP Server

OAM

command/

response

…Other Block

CHAPTER 5. Supplementary Functions and Tools

5.2 CLI

The CLI can be used for eNB operations and maintenance. The operator can log onto the

eNB via telnet over the PC that is allowed access through the eNB Ethernet, and perform

operations/maintenance via the text-based CLI.

Below are the functions the CLI provides.

The CLI loads programs required by the eNB. It can initialize the eNB normally without

working with the LSM, and load specific devices selectively. The CLI can also reset or

restart the boards.

Configurations Management

The CLI can run man-machine commands (MMC) to view or change the eNB’s

configurations.

Status Management

The CLI manages statuses of the eNB’s processor and various devices.

Fault Management

The CLI checks the possibility of faults in the eNB’s processor and various devices, and

provides the operator with fault locations and details. The CLI displays both hardware and

software faults, so the operator can check all failures that occur in the eNB.

Diagnosis and Test

The CLI can run a diagnosis on connection paths, processors and other devices that the

eNB is running, and detect their faults. The major test functions that the CLI can perform

include measuring the sending output and the antenna diagnosis function, etc.

LTE eNB System Description

ABBREVIATION

3GPP 3rd Generation Partnership Project

64 QAM 64 Quadrature Amplitude Modulation

AC Admission Control

ACL Access Control List

ADC Analog to Digital Converter

AKA Authentication and Key Agreement

AM Acknowledged Mode

AMBR Aggregated Maximum Bit Rate

ANR Automatic Neighbor Relation

ARQ Automatic Repeat Request

AS Access Stratum

BGP Border Gateway Protocol

BSS Base Station System

C & M Control & Maintenance

CC Chase Combining

CLI Command Line Interface

CM Configuration Management

CoS Class of Service

CPLD Complex Programmable Logic Device

CPRI Common Public Radio Interface

CPS Call Processing Software

CS Circuit Service

CSAB CPS SON Agent Block

CSCU Cold Start Control Unit

ABBREVIATION

DAC Digital to Analog Converter

DBMS Database Management System

DD Device Driver

DFT Discrete Fourier Transform

DHCP Dynamic Host Configuration Protocol

DiffServ Differentiated Services

DL Downlink

DSCP Differentiated Services Code Point

DTM Dual Transfer Mode

DU Digital Unit

DUS Debugging Utility Service

ECCB eNB Call Control Block

ECMB eNB Common Management Block

ECS eNB Control processing Subsystem

EDS eNB Data processing Subsystem

EMC Electromagnetic Compatibility

EMI Electromagnetic Interference

EMS Element Management System

eNB evolved UTRAN Node-B

ENS Event Notification Service

E/O Electric-to-Optic

EPC Evolved Packet Core

EPS Evolved Packet System

ES Energy Saving

ESM Energy Saving Management

ESM EPC System Manager

E-UTRAN Evolved UTRAN

FANM-C4 Fan Module-C4

FDD Frequency Division Duplex

FE Fast Ethernet

FHS File-system Hierarchy Standard 2.2

FM Fault Management

FSTD Frequency Switched Transmit Diversity

FTP File Transfer Protocol

GBR Guaranteed Bit Rate

GE Gigabit Ethernet

GPRS General Packet Radio Service

GPS Global Positioning System

GTP GPRS Tunneling Protocol

LTE eNB System Description/Ver.1.0

GTPB GPRS Tunneling Protocol Block

GTP-U GTP-User

GW Gateway

HARQ Hybrid Automatic Repeat Request

HAS High Availability Service

HETM-FC Heater Module-FC

HO Handover

HSS Home Subscriber Server

HTTP Hypertext Transfer Protocol

HTTPs Hyper Text Transfer Protocol over SSL

ICIC Inter-Cell Interference Coordination

ICMP Internet Control Message Protocol

IDFT Inverse Discrete Fourier Transform

IETF Internet Engineering Task Force

IF Intermediate Frequency

IP Internet Protocol

IPRS IP Routing Software

IPSS IP Security Software

IPv4 Internet Protocol version 4

IPv6 Internet Protocol version 6

IR Incremental Redundancy

L8HU LTE eNB remote radio Head Unit

L9CA LTE eNB Channel card board Assembly

LNA Low Noise Amplifier

LSM LTE System Manager

LTE Long Term Evolution

MAC Media Access Control

MACB Medium Access Control Block

MBR Maximum Bit Rate

MCS Modulation Coding Scheme

MDS Message Delivery Service

MFS Miscellaneous Function Service

MIB Master Information Block

MIMO Multiple-Input Multiple-Output

MMC Man Machine Command

MME Mobility Management Entity

MSS Master SON Server

MU Multiuser

ABBREVIATION

NAS Non-Access Stratum

NE Network Element

NP Network Processing

NPC Network Processing Control

NR Neighbor Relation

NRT Neighbor Relation Table

OAM Operation and Maintenance

OCNS Orthogonal Channel Noise Simulator

OCS Online Charging System

O/E Optic-to-Electric

OFCS Offline Charging System

OFD Optic Fiber Distributor

OFDMA Orthogonal Frequency Division Multiple Access

OS Operating System

OSAB OAM SON Agent Block

OSPF Open Shortest Path First

OSS Operating Support System

PAPR Peak-to-Average Power Ratio

PCI Physical Cell Identity

PCRF Policy and Charging Rule Function

PDCB PDCP Block

PDCP Packet Data Convergence Protocol

PDN Packet Data Network

PDPU Power Distribution Panel Unit

PDU Protocol Data Unit

P-GW PDN Gateway

RLCB Radio Link Control Block

PLER Packet Loss Error Rate

PM Performance Management

PMI Precoding Matrix Indicator

PMIP Proxy Mobile IP

PRACH Physical Random Access Channel

PSS Primary Synchronization Signal

QCI QoS Class Identifier

QoS Quality of Service

QPSK Quadrature Phase Shift Keying

LTE eNB System Description/Ver.1.0

RACH Random Access Channel

RB Radio Bearer

RB Resource Block

RECS-B2 Rectifier System-B2

RET Remote Electrical Tilt

RF Radio Frequency

RFS Root File System

RLC Radio Link Control

RO RACH Optimization

RRH Remote Radio Head

RU Radio Unit

S1-AP S1 Application Protocol

SC Single Carrier

SC-FDMA Single Carrier Frequency Division Multiple Access

SCTB Stream Control Transmission protocol Block

SCTP Stream Control Transmission Protocol

SDU Service Data Unit

SFBC Space Frequency Block Coding

SFN System Fame Number

SFTP SSH File Transfer Protocol

S-GW Serving Gateway

SIBs System Information Blocks

SM Spatial Multiplexing

SMC Security Mode Command

SMS Short Message Service

SNMP Simple Network Management Protocol

SON Self Organizing Network

SPD Surge Protect Device

SSH Secure Shell

SSS Secondary Synchronization Signal

STBC Space Time Block Coding

SU Single User

SwM Software Management

TA Tracking Area

THS Task Handling Service

TM Test Management

TOD Time Of Day

TrM Trace Management

ABBREVIATION

UADB Universal platform type A Digital Backplane board assembly

UADU Universal platform type A Digital Unit

UAMA Universal platform type A Management board Assembly

UCCM Universal Core Clock Module

UDA User Defined Alarm

UDE User Defined Ethernet

UDP User Datagram Protocol

UE User Equipment

UL Uplink

UTRAN UMTS Terrestrial Radio Access Network

VLAN Virtual Local Area Network

VSWR Voltage Standing Wave Ratio

Web-EMT Web-based Element Maintenance Terminal

LTE eNB

System Description

Information in this manual is proprietary to SAMSUNG

Electronics Co., Ltd.

No information contained here may be copied, translated,

transcribed or duplicated by any form without the prior written

consent of SAMSUNG.

Information in this manual is subject to change without notice.

MPE Information

Warning: Exposure to Radio Frequency Radiation The radiated output power

of this device is far below the FCC radio frequency exposure limits.

Nevertheless, the device should be used in such a manner that the potential

for human contact during normal operation is minimized. In order to avoid

the possibility of exceeding the FCC radio frequency exposure limits, human

proximity to the antenna should not be less than 900cm during normal

operation. The gain of the antenna is 19.8 dBi.The antenna(s) used for this

transmitter must not be co-located or operating in conjunction with any other

antenna or transmitter.

Samsung Electronics Co SLS-2C40680700 Remote Radio Head User Manual LTE eNB System Description

Samsung Electronics Co Ltd Remote Radio Head LTE eNB System Description

Manual

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