Читать книгу Mobile Communications Systems Development - Rajib Taid - Страница 96

This chapter covers the methods for encoding and decoding of control plane or signaling messages and protocol data units (PDUs) that are exchanged between the peer protocols layers of network elements of mobile communications networks, from the Global System for Mobile Communication (GSM) to the 5G system. The method of a description of signaling messages and their encoding and decoding is part of a protocol layer specification, which differs from one logical interface to another one. Messages are exchanged between the network elements of a mobile communications network to facilitate various communication services to users. A source network element creates a protocol layer message in a predefined format using a particular encoding/packing method and sends it to the peer network element over the concerned logical interface. The peer network element decodes or unpacks a message using the same method that was used to encode it.

We begin with the description of encoding and decoding methods of air interface Layer 3 signaling messages, followed by the Layer 2 signaling messages exchanged between a Mobile station (MS)/User Equipment (UE) and the network. We also cover the encoding method used by the Radio Access Network (RAN) and core network (CN) elements. We close this chapter with the method of embedding a control plane message within another control plane message to reduce signaling overhead between two network elements, especially over the air interface.