Radio access networks (RANs) connect mobile base stations to the mobile backhaul network. RANs have evolved from second-generation (2G) networks with GSM handsets to third-generation (3G) networks, which introduce IP. However, 3G networks do not offer true IP-based service. Rather, SSGN tunnels the data portion of the traffic to general packet radio service (GPRS) routers, which act as gateways to IP-based networks. The next phase, fourth-generation (4G) networks, commonly called Long-Term Evolution (LTE), introduces more IP into mobile backhaul networks, transforming RANs into IP RANs. In LTE networks, voice packets are encapsulated into IP packets and are transmitted over IP RAN, not over the legacy public switched telephone network (PSTN) as is the case with 3G networks.
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.
11.1 Evolution from 2G to 4G
This book focuses on QOS in packet-based networks, and this chapter presents a QOS case study for IP-based RAN as part of a mobile backhaul network. However, a brief introduction of 3G network evolution to 4G and LTE is necessary to describe the fundamental changes that occur with LTE ...