Zte ZXG10 OB06, Technical Manual

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ZXG10 OB06 ZTE Integrated Outdoor GSM Base Station Technical Manual
32 Confidential and Proprietary Information of ZTE CORPORATION
Protocol Introduction
Two important external interfaces for the ZXG10 OB06 (V1.0) are the Abis
and the Um interface.
On the Abis and the Um interface, the ZXG10 OB06 (V1.0) processes the
LapD protocol, LapDm protocol and RR/MM/CM protocol. The following are
descriptions of the three protocols in combination with the actual system
circumstance.
LapD Protocol
LapD (link access procedure of “D” channel) is a data link procedure for
signaling transmission between ZXG10 OB06 (V1.0) and BSC, with the
purpose of using the D channel to transmit messages between Layer-3
entities.
LapD is a point-to-multipoint communication protocol that employs the
frame structure.
In the ZXG10 OB06 (V1.0), LapD implements the following functions:
1. Providing one or multiple data connections in the D channel
The data link connections are identified by the DLCIs in the frames.
DLCI consists of the Terminal Equipment Identifier (TEI) and Service
Access Point Identifier (SAPI), indicating the service and entity that are
accessed.
2. Delimitation, location and transparency of the frame
3. Sequence control, ensuring sequential transmission of the frames
4. Error detection
5. Error recovering
6. Notifying the management entity of the un-recoverable error
7. Traffic control
Functions 1, 2 and 4 hereof are implemented automatically by the
hardware, while functions 3, 5, 6 and 7 are implemented through the
software.