Читать книгу Mobile Communications Systems Development - Rajib Taid - Страница 115

This chapter presented the CSN.1, ASN.1, direct, indirect, tabular format, and so on and methods of describing and encoding/decoding protocol layer messages across the different mobile communications systems from the GSM to the 5G system. The peer protocol layers of network elements of a mobile communications network exchange signaling messages using a particular encoding/decoding method as described in this chapter. These encoding and decoding methods are used over their respective logical interfaces, e.g. air interface Layer 2, Layer 3, NAS layer, between RAN and CN, and so on, to exchange control plane information. In comparison to the other encoding methods described in this chapter, the CSN.1 encoding method produces more compact protocol layer messages that are to be transmitted over the GPRS air interface.

An encoding and decoding method represents the data structures of IEs of messages that are used during the software design and development of protocol layers supported by the network elements of a mobile communications network. An IE of a message may contain and may be encoded with several information. Unlike the traditional IP layer header and packet, information may be encoded/decoded even at a single bit level in a mobile communications message. Correctly encoding and decoding of an IE, its components, and the value of a control plane or data plane message is important for the successful operation of a mobile communications network. It is also important from the interworking and interoperation point of view. We then closed the chapter with the method of piggybacking of a signaling message over another signaling message, thus reducing signaling overhead, be it over the air interface or between CN elements.