User's Guide

Nortel Networks Confidential
108
UMT/DCL/DD/0002
411--8111--905
Preliminary 01.06/EN october 2001
UMTS01
Digital TRM board (dTRM)
The digital board functions are the following:
reception of (up to) six transmit signals from the CCM
reception of the six signals from the antennas (main and diversity)
recovery and distribution of the clock
control and monitoring of the radio modules (TRX, MCPA, DDM)
supply voltages for radio board
Radio TRM board (rTRM)
The radio board performs the following functions:
in the downlink path
x digital--to--analog conversion
x frequency up--conversion
x amplification
in the uplink path
x frequency down--conversion
x analog--to--digital conversion
The rTRM board consists of three transmit chains and three dual receive chains.
Detailed functional description
General
Downlink path
The dTRM board receives up to six signals from the CCM. These downlink samples are transferred to
the Tx channelizers. Thechannelizers perform chip level modulation, peak power reduction, filtering,and
then deliver the signals (three max) to the D/A converters of the rTRM board.
In the analog domain, the digital signals are transformed into RF signals through D/A conversion,
modulation, filtering/amplification and translation operations. The final RF signals have the appropriate
level to drive the MCPA.
The total transmitted power is proportional to the data rate of the codes and the number of these codes
(communications). A power control adjusts each RF signal to optimise the total interference level noise
between the iBTS and the user equipment.
Uplink branch
The uplink branch handles three pair--received signals (main and diversity) coming from the antenna via
a coupling system which separates transmission from reception.These signalsare filtered,amplificated,
demodulated, A/D converted and then transmitted to the Rx channelizers in the digital domain.