GSM A-interface (BSS - MSC)

1. 基本描述： ts 48.001


2. BSS - MSC 功能划分原则：ts 48.002

2.1 一般来说，用 MSC( Mobile Core Network) 代表核心网的用户面和控制面。有些情况下,MSC被分为两部分MSC-Server(MSC-S)和Media Gateway（MGW).

2.2 Mobility management
All transactions concerning mobility management (as specified in 3GPP TS 44.018) shall take place transparently between the MS and MSC/VLR/HLR, using the protocols described in Technical Specifications 3GPP TS 48.008 and 3GPP TS 48.006. The only exception to this rule is that of paging which is scheduled by the BSS on the appropriate cell.

2.3 Call control 由 MSC/HLR/VLR 负责


3. 信令传输： ts 48.006

3.1 The MTP and the SCCP are used to support signalling messages between the MSC and the BSS

3.2 One user function of the SCCP, called BSS Application Part (BSSAP) is defined. In the case of point-to-point calls the BSSAP uses one signalling connection per active Mobile Station having one or more active transactions for the transfer of layer 3 messages. The BSSAP user function is further subdivided into two separate functions:

3.2.1 he Direct Transfer Application sub-Part (DTAP) is used to transfer messages between the MSC and the MS; the layer-3 information in these messages is not interpreted by the BSS.

3.2.2 he BSS Management Application sub-Part (BSSMAP) supports other procedures between the MSC and the BSS related to the MS (resource management, handover control), or to a cell within the BSS, or to the whole BSS.


4. L3 specifications: ts 48.008

4.1 BSC负责管理本地的无线资源

4.2 CC(call control) 和MM(Mobility Management)消息，BSS使用DTAP协议传递给MSC，不做处理

4.3 从Radio收到的initial L3 message，BSS初步分析后使用BSSMAP的COMPLETE LAYER 3 INFORMATION消息传递给MSC.(eg. CM SERVICE REQUEST, PAGING RESPONSE, CM REESTABLISHMENT REQUEST, LOCATION UPDATING REQUEST, IMSI DETACH, IMMEDIATE SETUP)