Case Study IP RAN and Mobile Backhaul QOS
Radio Access Networks (RANs) connect mobile base stations to the mobile backhaul network. RAN networks have evolved from 2G networks with GSM handsets to 3G, which introduces IP. However, 3G networks do not offer true IP-based service. Rather, SSGN tunnels the data portion of the traffic to GPRS routers, which act as gateways to IP-based networks. The next phase, 4G networks, commonly called Long-Term Evolution (LTE), introduces more IP into mobile backhaul networks, transforming RAN networks into IP RAN networks. In LTE networks, voice packets are encapsulated into IP packets and are transmitted over IP RAN, not over the legacy PSTN network as is the case with 3G.
This case study examines the recently evolved LTE network, with a focus on packet-based QOS. It starts by discussing the components of 2G and 3G networks, how traffic is carried on these networks, and how they have evolved to LTE. The case study then describes the LTE network components and traffic, and offers guidelines and suggestions for using QOS.
Before starting, we should note that currently, only a limited number of LTE networks have been installed, and they are only small-scale implementations operating in a trial or test mode. So if we ask whether QOS been successfully designed, verified, and implemented in these islands of LTE networks, the answer is, of course not. To reflect this reality, this chapter does not deliver truths gained from long experience and written ...