Lapdm Protocol - Zte ZXG10 OB06 Technical Manual

ZXG10 OB06 ZTE Integrated Outdoor GSM Base Station Technical Manual
SAPI. The LapD supports three types of information: signaling
(including short message information), O&M information and LapD
layer management information. Links of the three kinds of information
are distinguished by SAPI. SAPI=0 represents the signaling link,
SAPI=62 represents the O&M link, and SAPI=63 represents the
management link of the LapD layer.
In the control field, N(S) represents the sending serial number and the
I frame's serial number currently sent by the sending end; N(R)
represents the receiving serial number, the expected sending serial
number of the next I frame. N(R) is used to predict the instruction
from the receiving end.
Frame Check Sequence (FCS) is used for error code detection.
Flag is the beginning and the end token of a frame, namely, a 8-bit
font containing six consecutive 1s.
2. UI frame operation
The L3 message is sent in the no-serial-number frame mode, and the
receiver is not required to send the received confirmation after
receiving the UI frame. This operation mode does not provide flow
control or error recovering mechanism.
The UI frame structure is shown in Figure 17. It consists of the address
field, control field and information field.
F
I G U R E
SAPI
The address field contains SAPI and TEI. In the address field, P
represents the query bit; if this bit is set to 1, it means to require the
response frame from the peer entity.

LapDm Protocol

In GSM, LapDm is a data link protocol for signaling transmission between
MS and ZXG10 OB06 (V1.0), with the purpose of using the Dm channel to
transmit messages for entities of Layer 3 through the radio interface.
LapDm is based on LapD, with some simplification and modification.
In the ZXG10 OB06 (V1.0), LapDm implements the following functions:
1. In a Dm channel, providing a point-to-point data link connection and
multiple services for the upper layer. The data link connections are
identified by the DLCIs in the frames. The DLCI only contains SAPI,
indicating the service that is accessed.
34 Confidential and Proprietary Information of ZTE CORPORATION
1 7 U I F S
R A M E T R U C T U R E O F
Address
Control Information
TEI
L D
A P
000 P 0011