User Manual
Airbridge cBTS3612 CDMA Base Station
System Description
2 Hardware Architecture
2-10
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:
l
In uplink direction, backplane bus receives O&M command from BCKM and
traffic data from BCPM, and transmit ATM cells on the multiple E1 links with
IMA technology in compliance with G.804 standards to BSC.
l
In downlink direction, it receives ATM cells distributed on the multiple E1 links
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.
l
Each BCIM provides 8 E1 links, which can support at most 4 IMA link sets. In
BTS, there are two BCIMs, providing physical interfaces to BSC in load sharing
mode. At most 16 E1 links can be provided.
l
It communicates with BSC through IMA state machine program on the local
board, and monitors the working status of E1 link and ensuring the
implementation of IMA protocol.
l
It transmits O&M command through backplane bus or out-band signaling serial
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 module
CPU module
Control bus
Data bus
E1
RS232
Backplane
bus
BCKM
BESP
IMA module
...
Power supply
module
Clock module
Figure 2-5
Structure of BCIM module
