User Manual

Architecture
Nortel Networks Confidential
3–46
PE/DCL/DD/0063
411–9001–063
Standard 12.07/EN September 2000
GSM/BSS V12
The dynamic power is provided by the ASIC of the TX logical unit. Its software
reads the value and commands the TX–driver accordingly.
In the case of a BCCH filler, the additional attenuation introduced is always zero.
The power values that the TX and the mobile have to use are fixed by the BTS
according to a control algorithm using the measurements results that it makes and
the thresholds stockpiled in the OMC. The mobile and the BTS power control can
be inhibited by the OMC.
The power control aim is to minimize the interferences, ensure good transmission
quality and save mobile’s batteries.
Power slaving
The setpoint value is slaved to compensate for gain variations of the transmission
chain.
Two slaving loops are used to compensate for attenuation in the gain chain (see
Figure 3–14).
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TX LOGIC
External loop
GMSK Modulation
Internal loop
Radio Frequency
Antenna
TX DRIVER
Control bus
PA or LPA
Figure 3–14 Power slaving diagram
These loops may be in the following states:
Open: This state is used for calibration of the internal loop with the external loop.
Initialization: This state is used for loop start–up.
Error: A loop is in error when it is not longer in correspondence with the setpoint.
Closed: A loop is closed when it is in slow slaved mode.