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User Manual
Airbridge cBTS3612 CDMA Base Station
Protocol stack used by Abis traffic is as follows:
II. Physical layer
The physical layer of Abis interface can use E1/T1 interface or STM -1 interface.
With E1/T1 interface used, its physical electric parameters comply with CCITT
G.703 recommendations. The multiple E1/T1 trunk lines transmit ATM cells by
means of Inverse Multiplexing on ATM (IMA).
III. Data link layer
ATM is used in the data link layer of Abis interface.
Adaptation of Abis signaling is performed on the basis of AAL5, and is borne in IP
Over ATM (IPoA ) mode. At Abis interface, Abis signaling path connects the main
control software (MC) and SPU of BSC via Permanent Virtual Circuit (PVC) to
transmit Abis signaling. So it is with the transmission path of signaling that performs
operation & maintenance. It also uses PVC to connect OMU of BTS and BSC, which
will forward it to OMC transparently. BSC does not process any signaling that
performs operation and maintenance.
Adaptation of Abis traffic is performed on the basis of AAL2. At Abis interface,
BCPM uses several PVCs to connect the channel processing unit of BTS and SDU
of BSC, for BTS to transmit the uplink data received from the air interface to BSC,
and for BSC to transmit the downlink data to be transmitted via the air interface to
BTS.
IV. Layer 3 - traffic management
At Abis interface, Abis signaling and Abis traffic are in the domain of traffic
management. Specifically, Abis traffic management includes the following functions:
1) BTS logic operation & maintenance function
Resource status indication: with this function, BTS requests logic configuration
l
from BSC, reports logic status to BSC and checks logic resource regularly.
Cell configuration: with this function, BSC configures logic parameters of cells
l
for BTS, including cell pilot Pseudo Noise (PN) offset, sector gain, common
channel number and parameter.
Overhead message updating: with this function, BSC configures or update
l
overhead message to BTS.
Abis Traffic
SSSAR
AAL2
ATM
Physical Layer
1-16
System Description
1 System Overview
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