CDMA Interface

8.1.1          Descriptions of inter-entity interfaces

  Interface between MSC and BSS (A-interface)

In fact, it is the interface between MSC and BSC. Adopting 2Mb/s PCM digital link, the standard protocols for this interface include IS-634, IOS2.4, IOS4.0 etc.

A-interface is mainly used to transmit the following information:

1. BSS management information,

2. Call processing, and

3. Mobility management information.

 Interface between MSC and VLR (B-interface)

This interface is an internal interface, without standard definition. Its functions are as follows:

VLR is the location and management database for subscribers that have roamed into related MSC area. When the MSC needs the subscriber data of the particular MSC area, the MSC is to inquire the VLR; in the case of mobile station location updating, the MSC will request VLR to store the related information; when the user activates the supplementary services or modifies data, the MSC will request the HLR (through VLR) to store the related data.

This interface has no standard definition, and generally uses an internal interface.

 Interface between MSC and HLR (C-interface)

Interface between the MSC and the HLR.

The system adopts the IS-41E protocol. This interface is based on 2Mb/s digital interface or 64Kb/s interface, with its interface electrical performance conforming to GF002-9002.1 The General Technical Specifications for Telephone Switching Equipment of the Ministry of Posts and Telecommunications Volume 1 Digital SPC Switching Equipment General Technical Specifications Chapter 7 and GB7611-87 Pulse Coding Modulation Communication System Network Digital Interface Parameters; As for the signaling specifications, for detailed description of MAP, refer to Technical Requirements for 800MHz CDMA Digital Cellular Mobile Communication Network Mobile Application Part (MAP); for detailed description of SCCP, refer to GF010-95 Technical Requirements for National No.7 Signaling Mode Technical Specifications Signaling Connection Control Part (SCCP); for detailed description of MTP, refer to GF001-9001 China Telephone Network No.7 Signaling Mode Technical Specifications.

C-interface adopts 24-bit No.7 signaling mode.

  Interface between VLR and HLR (D-interface)

The system adopts the IS-41E protocol. This interface is based on 2Mb/s digital interface or 64Kb/s interface , with its interface electrical performance conforming to GF002-9002.1 The General Technical Specifications for Telephone Switching Equipment of the Ministry of Posts and Telecommunications Volume 1 Digital SPC Switching Equipment General Technical Specifications Chapter 7 and GB7611-87 Pulse Coding Modulation Communication System Network Digital Interface Parameters; As for the signaling specifications, for detailed description of MAP, refer to Technical Requirements for 800MHz CDMA Digital Cellular Mobile Communication Network Mobile Application Part (MAP); for detailed description of SCCP, refer to GF010-95 Technical Requirements for National No.7 Signaling Mode Technical Specifications Signaling Connection Control Part (SCCP); for detailed description of MTP, refer to GF001-9001 China Telephone Network No.7 Signaling Mode Technical Specifications.

D-interface uses 24-bit No.7 signaling mode.

This interface is used for switching of subscriber location information, authorization information and service data. The major service function of a mobile station is: it must have the capability of initiating and receiving calls within the service area. In order to support this capability, the HLR has to perform data switching. The VLR notifies the HLR about the subscriber location information, and provides the subscriber roaming number. The HLR sends the subscriber service data required by the VLR. The switching data usually occurs when a subscriber requests for a special service, or when a subscriber or network operator modifies the subscriber data.

  Interface between MSC and MSC (E-interface)

The system adopts the IS-41E protocol. This interface is based on 2Mb/s digital interface or 64Kb/s interface, with its interface electrical performance conforming to GF002-9002.1 The General Technical Specifications for Telephone Switching Equipment of the Ministry of Posts and Telecommunications Volume 1 Digital SPC Switching Equipment General Technical Specifications Chapter 7 and GB7611-87 Pulse Coding Modulation Communication System Network Digital Interface Parameters; as for the signaling specifications, for detailed description of MAP, refer to Technical Requirements for 800MHz CDMA Digital Cellular Mobile Communication Network Mobile Application Part (MAP); for detailed description of SCCP, refer to GF010-95 Technical Requirements for National No.7 Signaling Mode Technical Specifications Signaling Connection Control Part (SCCP); for detailed description of MTP, refer to GF001-9001 China Telephone Network No.7 Signaling Mode Technical Specifications.; the ISUP part is still to be defined.

E-interface adopts the 24bit No.7 signaling mode. Its functions are as follows:

When a mobile station roams from one MSC to another, the MSC will perform handoff in order to keep the subscribers’ conversation uninterrupted. In this case data switching must be implemented between the MSCs.

 Interface between MSC and EIR (F-interface)

This interface has no standard definition. Its functions are as follows:

When the mobile station is in communication, and the MSC authenticates the mobile station, it has to inquire the EIR, so as to determine whether the mobile station is legal, and thus deciding whether to provide services to this mobile station.

 Interface between HLR and AUC (H-interface)

Currently an internal interface is used. Its functions are as follows:

When the HLR receives an authentication request from an MS, the HLR gets data from the AUC. When the AUC initiates the authentication instruction to the MS, the AUC transfers the authentication information to the subscriber via the HLR.

  Interface between MC and SME and MC (M-interface)

Current the SMPP phase III standard is used. The interface’s function is as follows:

When the short message center performs information interaction with the short message entity and another short message center, this protocol must be abided by.

 Interface between HLR and MC (N-interface)

The interface standard is ANSI-41E. Its function is as follows:

When the short message center sends a short message to a subscriber, if the called subscriber’s address information is not available, it has to inquire the HLR for the subscriber’s route before it can send the short message to the subscriber.

  Interface between MC and MSC (Q-interface)

The interface standard is ANSI-41E. Its function is as follows:

During the submission and reception of a short message, short message transfer needs to be conducted between the short message center and mobile switching center. At the same time, when the subscriber’s short message capability changes, the mobile switching center needs to notify the short message center in time.

  Interface between MSC and OMC

This interface conforms to the network requirements of TMN, and provides standard Q3 interface to the upper-level TMN.

   Interfaces with PSTN/ISDN (Ai/Di Interfaces)

The CDMA digital cellular mobile network inter-works with PSTN/ISDN through the mobile switching center (MSC) and provides voice, data and certain supplementary services for subscribers. Its interfaces are 2048kb/s-based digital interfaces. TUP and ISUP of the SS7 signaling are adopted with priority as the interface signaling specifications. Where conditions are not available, China No.1 signaling can be used.

   Interfaces with Other PLMN Networks

The CDMA digital mobile network is normally connected with different types of PLMN networks (such as GSM) through other public networks (such as PSTN and ISDN), or directly connected with other types of PLMN networks. The adopted protocol can be TUP or ISUP, or China No.1 signaling.