Reference Manual

Frequency Allocation Support
40 Frequency Allocation Support
The FAS function measures the interference level on a number of
frequencies, specified by the operator. The measurements are performed
on idle channels or idle burst positions.
The TRXC:s execute the FAS function independently of each other
(however all TRXC:s don’t have to be used). Thus it is here described
only how the FAS function works on one TRXC.
FAS measurements can start when the TRXC has been configured with
a list of FAS frequencies. Measurements are performed during one or
several FAS measurement periods.
Each FAS measurement period is started and stopped by Abis O&M
messages. During the FAS measurement period the TRXC shall handle
the measurement of the signal levels, on all specified frequencies, once
every 15:th second and accumulate the result in one histogram for each
frequency.
The result of the measurements is reported on Abis O&M interface on
request as calculated median and percentile values for each frequency.
The number of times each frequency has been measured on is also
reported.
40.1 References
/GSM:05.05/
40.2 Concepts
Percentile value: The proportion of samples in a distribution.
An example: The 90 percentile value for a distribution is the value for
which 90 percent of the samples have a value equal to or less than the
percentile value.
40.3 Functions
40.3.1 FAS configuration
A Frequency List is received on Abis O&M interface containing
maximum 150 frequencies to measure on. The frequencies are coded in
a way that can be interpreted as ARFCN:s with a value ranging from 0
until 1023. This value range is accepted (The BTS can however only
measure on frequencies for which it has capability). The relation
between frequencies and ARFCN:s is specified in /GSM:05.5:1.1/.
The FAS support capability and the number of frequencies transferred
are checked.
All eventually on-going measurements are stopped.
Measurement result are cleared.
40.3.2 Start measurement
FAS measurement will be started by O&M message. Old measurement
results are Optionally cleared.
EN/LZT 720 0008 P2A
2001-11-28
327 (485)
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