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User Manual
Airbridge cBTS3612 CDMA Base Station
1) Composition of Abis interface
Abis interface consists of three parts: Abis traffic, Abis signaling and OML signaling,
as shown in Figure 1-5.
Abis traffic is the interface connecting SDU of BSC and the channel processing unit
of BTS. It is used to bear user traffic.
Abis signaling is the signaling transmission channel between BSC and BTS. It is
used to control the cell setup, transmission of messages in paging channels and
access channels, and call setup & release.
OML signaling is used to perform operation and maintenance. It is defined by
equipment manufacturers. On Abis interface, there is a transparent channel used to
bear OML between OMC and OMU of BTS.
Abis Interface
SPU ： Signaling Process Unit
SDU ： Selection/Distribution Unit
MC ： Main Control
Figure 1-5 Composition of Abis interface
2) Protocol stack of Abis interface
The protocol stack used by Abis signaling and the signaling for operation &
maintenance is as follows:
Abis Signaling Application/OAM Application
SPU
MC
CEs
OMU
BTS
TCP
IP
AAL5
ATM
Physical Layer
SDU
BSC
OMU
CEs
BTS
CEs ： Channel Elements
OMU ： Operation & Maintenace Unit
1-15
System Description
1 System Overview
MC
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