Chapter 12
Toward an All-IP Core Network
In this chapter we continue the story from Chapter 11 of the convergence of wireless and IP networks toward an all-IP wireless networks. We have seen in Chapter 11 how IP has been retrofitted to support voice (using such technologies as RTP and SIP) with QoS control. In this chapter we proceed in Section 12.1 to show how IP has also been retrofitted to support other aspects of using it in wireless networks, including mobility support and more limited bandwidth than in wired networks. We then discuss in Section 12.2 how GSM has evolved to add more support for packet data networking, with the addition of GPRS. Moving beyond GPRS, in Section 12.3 we trace the continued evolution of wireless networks, up to LTE. An important development is the addition of the IP multimedia subsystem (IMS) in UMTS/LTE, so we explain IMS concepts in Section 12.4. Finally, in Section 12.5 we look briefly at how other networks (from other tracks of development besides UMTS) have been moving in the same direction—toward convergence with IP networks.
12.1 Making IP work with wireless
One of the beauties of IP routing is the hierarchical addressing scheme. It allows aggregation of addresses; that is, an entire block of contiguous addresses (including very large blocks of addresses) can be referenced by a single network address. All the addresses in the block share the same network prefix, and thus that shared network prefix is used as the single network address to ...
