External Interfaces - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station
I. Receiving signal low noise amplification and distribution unit
There are 4 LNAs and distributors inside the RLDU, which process 4 signals. The 4
LNAs have the same specifications such as gain, noise factor and dynamic to ensure
the balance among 4 receive paths.
II. Configuration switch unit
The electronic switches inside the RLDU are designed for supporting different BTS
configurations. When the BTS is configured in the 3-sector mode, the electronic
switches can be set to make the RLDU operate in the single-sector mode that has two
main/diversity receiving paths (Each path provides 1-in-4 output to support 1~4 carriers
configuration for each sector). When the BTS is configured in the 6-sector mode, the
electronic switches can be set to make the LDU operate in the 2-sector mode. And
each sector provides 4 main/diversity receive paths (Each path provides 1-in-2 output,
supporting 1~2 carriers configuration in each sector).
III. Antenna VSWR and LNA status monitoring unit
The transmitted forward/reverse power coupling signals from the CDU or the DFU or
the DDU are processed in the antenna VSWR monitoring circuit inside the RLDU.
When the VSWR of transmitting antenna exceeds a specified threshold, alarm will
occur. At the same time, the RLDU also converts transmit coupling power signal into
DC level signal through its RF power detecting circuits. Through this DC level signal,
any exception of transmit signal power of antenna can be monitored in realtime. LNA
status monitoring circuit monitors the voltage and current of the 4 LNAs inside the
RLDU. It generates alarm when fault t is found.

3.8.3 External Interfaces

RLDU is the reverse link function module of the BTS, which interfaces with CDU/DFU
and BTRM in both input and output sides through the two sets of 8W8 D-type
combination blind mate connectors on the back of the module.
Interface signals between the RLDU and the CDU/DFU/DDU are:
Main/diversity path receiving RF signals outputted from two CDU/DFU/DDU
receive filters. They are amplified and distributed by the RLDU.
The CDU/DFU/DDU coupling RF signals, which are used for antenna VSWR
monitoring and forward power detection.
Interface signals between the RLDU and the BTRM are:
Main/diversity path receiving RF signals transmitted to the BTRM after being
amplified and distributed.
Chapter 3 Radio Frequency Subsystem
3-17
System Principle