4G Access Network Architecture

Although all-IP networking is the ultimate goal of 4G wireless networks, 3G LTE and WiMAX systems have designed semi all-IP network architectures for efficient radio resource and mobility management. These semi all-IP networks separate layer 2 and layer 3 handoff operations by grouping many base stations (BSs) as a subnet, thus alleviating handoff, while the pure all-IP networks provide a simple network platform at the cost of high handoff overhead. The authors compare the semi all-IP networks to the pure all-IP networks, and provide an overview to WiMAX access service networks and 3G LTE backhaul networks. They then present advanced architectures that support efficient radio resource and mobility management. First, they present a semi hierarchical cellular system with a super BS that behaves like a normal BS as well as a supervisor over other BSs within the group. They further extend this model to a system that combines multiple access techniques of OFDMA and FH-OFDMA with microcells and macrocells. Also, to alleviate the handoff latency, a dual-linked BS model is presented in order to support seamless handoff. Finally, as an integrated approach to supporting diverse QoS requirements, the authors consider an IP-triggered resource allocation strategy (ITRAS) that exploits IntServ and DiffServ of the network layer to interwork with channel allocation and multiple access of MAC and PHY layers, respectively. These cross layer approaches shed light on designing a QoS support model in a 4G network that cannot be handled properly by a single layer based approach.