Alvarion Technologies IF-24-SYNC Broadband Wireless Access System User Manual Flexible Hopping Definition Mode

Alvarion Ltd. Broadband Wireless Access System Flexible Hopping Definition Mode

Contents

Appendix

Appendix – Hybrid Digital Modulation
Flexible Hopping Definition for Models with
FCC ID LKT-IF-24-SYNC
General
This addendum applies to BreezeACCESS II models that have been factory
shipped or field upgraded to operate as a hybrid digital transmitter with FCC
ID: LKT-IF-24-SYNC.
The hardware, software features, and menus all remain the same as the FHSS
version of the product, except for the addition of the flexible hopping control
menus as described below.
According to the FCC grant for models operating as HDM, the
transmitted output power of the AU and SU units must be adjusted to
limit the maximum power into the antenna to 19 dBm. Reference the
BreezeACCESS Version 4.3 Revision 3.0 System Manual Book 4:
Operations and Administration (2-44, 2-45) for detail description on
menus and parameter settings.
For IF based units only (AU-BS/AU-NI; SU-A/SU-E) this is done by configuring
the Transmit Power Control parameter to control the gain of the TX power
circuits. Actual parameter setting is based on the IF cable attenuation relative
to the cable length and type used at installation. For non-IF based SU units
(SU-R/SU-I) power control is limited through a Power Level configuration which
is based on High or Low value parameter.
The process of setting the hopping sequence using the Flexible Hopping
Definition mode includes the following steps:
1. Select the frequencies to be used using the Flexible Hopping Definition
menu
2. Define the method of generating the basic hopping sequence based on
the set of selected frequencies, using the Scrambling Definition sub-
menu. The method of generating the basic sequence also defines the
hopping shift mechanism for generating different actual hopping
sequences.
3. Configure the Hopping Shift parameter to define a different hopping
sequence for each AU in order to minimize interference between adjacent
AUs.
The Flexible Hopping Definition menu enables defining the hopping
frequencies and the method of scrambling the selected frequencies for
generating the basic hopping sequence. It also enables to view the selected
hopping frequencies and the current hopping sequence (based on the
previous selections made before the last reset). The new selections will come
into effect only after the next reset. In cases where all frequencies were
deleted the default frequency is 2401 MHz.
Frequencies Selection and Basic Sequence
Generation Using the Flexible Hopping
Definition Menu
The Flexible Hopping Definition menu includes the following options:
Add Frequencies
The Add Frequencies option enables defining a new list of sub-bands and/or
discrete frequencies. Enter a list of the required sub-bands and/or
frequencies, using either sub-bands (f1-f2) or discrete frequencies, e.g. 2402-
2412,2448,2470-2480. Use a comma to separate between entries, do not
use spaces.
The usable center frequencies are from 2402 to 2480, using a 1 MHz
resolution (2402,2403,2404 … 2480).
The new selected set of frequencies (frequencies to be used) will become
effective only after the next reset.
Remove Frequencies
The Remove Frequencies option enables removing previously defined sub-
bands and/or discrete frequencies. Enter a list of the required sub-bands
and/or frequencies to remove, using either sub-bands (f1-f2) or discrete
frequencies, e.g. 2402-2412,2448. Use a comma to separate between
entries, do not use spaces.
Erase All
The Erase All option enables erasing all previously defined sub-bands
and/or discrete frequencies. Enter option selection 1- Erase All.
Scrambling Definitions
The Scrambling Definition menu enables defining the method of organizing
the selected frequencies to form the actual hopping sequence to be used.
Proper organization of the hopping sequence is essential to guarantee
minimal cross interference among several neighboring cells that use the
same sequence with different Hopping Shift values.
Scrambling Mode
Defines the scrambling mode. The following options are available:
Standard Scrambling
This mode is not recommended for sequences with 7 or more channels. The
scrambled basic sequences for 3 to 6 frequencies when using Standard
Scrambling are:
Table Error! No text of specified style in document.Error! No text of specified style in
document.-1: Basic Sequences using Standard Scrambling
N (number of channels) Scrambled Basic Sequence (channel indexes)
3 1, 3, 2
4 1, 3, 2, 4
5 1, 3, 5, 2, 4
6 1, 3, 5, 2, 6, 4
Frequency 1 (index=1) is the lowest frequency in the list of frequencies to be
used, frequency 2 is the next frequency and so on.
Manual Scrambling
For customized definition of the hopping sequence, using the Manual
Sequence Definition option (see below).
Enhanced Scrambling
Automatically generates hopping sequences using an enhanced algorithm. It
is recommended that Enhanced Scrambling rather then Standard
Scrambling be used. If the Enhanced Scrambling Mode is selected, the
Spanning Factor parameter (see below) must be configured in the AU. The
Enhanced Mode is not suitable for sequences with 6 or less frequencies. If
Enhanced Scrambling is selected with sequences that have 6 or less
frequencies, than Standard Scrambling is used by default.
The scrambled sequence is generated according to the following rules:
1. The first channel in the basic scrambled sequence is frequency 1
(Frequency 1 (index=1) is the lowest frequency in the list of frequencies to
be used, frequency 2 is the next frequency and so on.)
2. The index of each of the other channels is calculated by adding the
Spanning Factor to the index of the previous channel. Note that the
sequence is cyclic, meaning that adding 1 to the highest index in the
sequence (Index=N where N is the number of channels in the sequence)
will result in the first channel (Index=1).
The scrambled basic sequence can also be calculated using the formula: Px
(j)= {[(j-1)*X]mod(N)}+1
Where:
X is the Spanning Factor
N is the number of channels in the sequence (modulus)
J is the sequence index
Example: N=8, X=3
P1(5)={[(1-1)*3}mod8}+1=1
P2(5)={[(2-1)*3}mod8}+1=6
P3(5)={[(3-1)*3}mod8}+1=3
P4(5)={[(4-1)*3}mod8}+1=8
P5(5)={[(5-1)*3}mod8}+1=5
P6(5)={[(6-1)*3}mod8}+1=2
P7(5)={[(7-1)*3}mod8}+1=7
P8(5)={[(8-1)*3}mod8}+1=4
And the basic scrambled sequence is: 1, 4, 7, 2, 5, 8, 3, 6.
Manual Sequence Definition
Manually defines the hopping sequence, using numbered channel indexes
(from 1 to “Number of Hopping Frequencies”). The sequence length must be
equal to “Number of Hopping Frequencies” (all the defined frequencies must
be used).
Erase Manual Sequence
Erases the manually defined hopping sequence.
Spanning Factor (AU only)
Defines the Spanning Factor to be used by the Enhanced Scrambling
mechanism. The Spanning Factor should be chosen so that the GCD
(Greater Common Divisor) of the Spanning Factor and the Number of
Hopping Frequencies would be 1 (e.g. for 8 frequencies possible values for
the Spanning Factor are 1, 3, 5 and 7). The SU learns the value of the
Spanning Factor from the AU during the association process.
Use of different spanning factors by non-synchronized neighboring base
stations reduces the probability of interference between adjacent sectors.
Valid values: 1 to Number of Hopping Frequencies minus 1, provided it
meets the GCD requirement as described above.
It is not recommended to use spanning factors of 1 and N-1, as they result in
hopping on consecutive channel (assuming that the available channels are
consecutive). In these cases the advantage of using frequency hopping is not
fully utilized, since narrow band interference may affect several consecutive
hops. Spanning factors of 2 and N-2 also result in a relatively poor spread of
the hopping frequencies over the available frequency band.
Default Value: 1
NOTE
It is always recommended to use a mid range or ½ N total channels used for the AU
Spanning Factor. For Example, If your AU Scrambling Definition is configured for a total
of 24 flexible hopping channels, choose a Spanning Factor of 12 or 13.
Show Flexible Hopping Parameters
Displays the following information:
An updated list of the defined sub-bands and discrete frequencies to
become effective after the next reset. A sub-band is defined by the first
and last hopping frequency in a series of consecutive frequencies, with
3MHz separation between frequencies.
An updated list of all the hopping frequencies to be used after the next
reset.
Scrambling Mode
Manual Sequence Definition (if applicable)
Spanning Factor (if applicable. In the SU it will be shown only when
operating in the Enhanced Scrambling mode)
The current sequence of operational hopping frequencies
After configuring the flexible hopping parameters, conclude your configuration
in accordance with the System Manual sections for Commissioning and
Operations and Administration.

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