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User Manual
Airbridge cBTS3612 CDMA Base Station
BCIM comprises the following parts:
1) IMA module
The purpose of IMA is to inversely multiplex an ATM cell flow based on cells into
multiple physical links for transmission. Another purpose is to remotely multiplex the
cell flows transmitted on different physical connections into a single ATM cell flow.
In uplink direction, IMA module receives AAL2 traffic cells from BCPM and AAL5
signaling cells from BCKM through the backplane bus. It splits the ATM cell flow into
cells, transmits them on multiple E1 link according to G.804 standard before sending
them to BSC.
In downlink direction, it receives ATM cells from BSC that are distributed on multiple
E1 trunk lines, inversely multiplexes them into a single ATM cell flow. Then it sends
AAL2 traffic cells to BCPM and AAL5 signaling cells to BCKM through the backplane
bus
2) CPU module
The main control CPU on BCIM implements such functions as initialization of
devices on BCIM, IMA protocol processing, executing OAM function of IMA, as well
as E1 trunk line management and communication with BCKM.
3) Backplane bus module
BCIM communicates with other boards in the baseband part through the backplane
bus module, including control information communication with BCKM and traffic data
communication with BCPM.
4) Power supply module
The power supply module implements DC/DC power conversion from +27V to 3.3V.
5) Clock module
It provides working clock for the local board.
III. Interface
E1 interface
l
Interface with BSC
Backplane bus interface
l
Interface with other boards in the bas eband part.
RS-232 serial port
l
As an emergency serial port, it is connected with UART as a standby node, used for
communicating with BCKM when other part of the board is faulty.
2-11
System Description
2 Hardware Architecture
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