User Manual

Dimensioning rulesNortel Networks Confidential 5–1
S8000/S8002/S8006 BTS Reference Manual
5 DIMENSIONING RULES
5.1 Generalities on dimensioning
Base Transceiver Stations (BTS) have to be dimensioned on both the radio and Abis
interfaces.
The dimensions of the interface with the Base Station Controller (BSC) is calculated
on the basis of traffic handled on the Abis interface PCM links.
5.1.1 RADIO interface dimensions
The dimensions of the radio interface with Mobile Stations (MS) are calculated on
the basis of the number of Traffic Channels (TCH) needed to handle the traffic, the
number of SDCCH/8, BCCH channels and the control channel (RACH, PCH,
AGCH) dimensions.
5.1.1.1 Traffic (TCH), signaling (SDCCH/8) and broadcasting (BCCH) channels
Each transceiver (TRX) manages eight channels that can each support traffic
(TCH), signaling (SDCCH), broadcasting (BCCH) and control (RACH, PCH,
AGCH) channels.
The average occupation of a traffic channel is 100 seconds per call for
approximately 15 seconds of occupation of a signaling channel. In all cases a
broadcasting channel is reserved for use by BCCH frequency filling and control
channel support.
Depending on the position of cells in relation to the location area, the number of
SDCCH channels is liable to change:
The SDCCH channel payload in cells in outer location areas is increased by
location updating procedures.
The same dimensioning rules govern multi–cell sites since each cell operates
independently at radio level.
The number of TCH in a TDMA depends on the type of the TDMA:
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