SGSN与MSC/VLR之间的通信，采用BSSAP+（Base Station System Application+）

【An overall cellular network contains a number of different elements from the base transceiver station (BTS) itself with its antenna back through a base station controller (BSC), and a mobile switching centre (MSC) to the location registers (HLR and VLR) and the link to the public switched telephone network (PSTN). Of the units within the cellular network, the BTS provides the direct communication with the mobile phones. There may be a small number of base stations then linked to a base station controller. This unit acts as a small centre to route calls to the required base station, and it also makes some decisions about which of the base station is best suited to a particular call. The links between the BTS and the BSC may use either land lines of even microwave links. Often the BTS antenna towers also support a small microwave dish antenna used for the link to the BSC. The BSC is often co-located with a BTS. The BSC interfaces with the mobile switching centre. This makes more widespread choices about the routing of calls and interfaces to the land line based PSTN as well as the HLR and VLR.】 From the paragraph above, in a cellular network, the （98） can provide direct communication with a mobile phone, the （99） acts as a small centre to route calls to the required base station, and it also makes some decisions about which of the base station is best suited to a particular call.（100） can be used to link the BSC with related BTS。

A. BSC B. BTS C. MSC D. VLR A. BSC B. BTS C. MSC D. HLR A. Land lines B. Microwave links C. Microwave dish antenna D. Land lines or microwave links

A.MSC/VLR与SGSN之间的接口

B.BSC与SGSN之间的接口

C.SGSN与GGSN之间的接口

D.MSC与BSC之间的接口

A．错误

B．正确

A.Gn

B.Gs

C.Gb

D.Gr

A．错误

B．正确