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User Manual
Airbridge cBTS3612 CDMA Base Station
2.2.3 Control Interface Module (BCIM)
I. Overview
BCIM is located in BTS baseband subrack. It is a functional entity for the connection
of BTS and BSC. Its major functions are as follows:
In uplink direction, backplane bus receives O&M command from BCKM and
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traffic data from BCPM, and transmit ATM cells on the multiple E1 links with
IMA technology in compliance with G.804 standards to BSC.
In downlink direction, it receives ATM cells distributed on the multiple E1 links
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from BSC, multiplexes them into a single ATM cell flow with IMA technology
and finally sends them to corresponding processing boards through the
backplane bus.
Each BCIM provides 8 E1 links, which can support at most 4 IMA link sets. In
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BTS, there are two BCIMs, providing physical interfaces to BSC in load sharing
mode. At most 16 E1 links can be provided.
It communicates with BSC through IMA state machine program on the local
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board, and monitors the working status of E1 link and ensuring the
implementation of IMA protocol.
It transmits O&M command through backplane bus or out-band signaling serial
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port, reports the status information of the local board to BCKM and provides
interface for board maintenance and network management.
II. Structure and principle
The structure of BCIM is as shown in Figure 2-5.
Backplane
bus
Figure 2-5 Structure of BCIM module
Backplane
CPU module
bus module
Clock module
2-10
System Description
2 Hardware Architecture
Data bus
RS232
IMA module
E1
Control bus
Power supply
module
BCKM
BESP
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