Resource Allocation in IEEE 802.16 Mobile WiMAX

In this chapter, we focus on the management of resource allocation and scheduling in IEEE 802.16e based mobile WiMAX networks. Since mobile WiMAX uses orthogonal frequency division multiple access (OFDMA), the scheduling issues can apply for other OFDMA-based networks as well. Unlike wireless LANs, WiMAX networks incorporate several Quality of Service (QoS) mechanisms at the media access control (MAC) layer for guaranteed services for data, voice, and video. The problem of assuring QoS is basically that of how to allocate available resources among users in order to meet the QoS criteria such as delay, delay jitter, and throughput requirements. IEEE standard does not include a standard scheduling mechanism and leaves it for vendor differentiation. Scheduling is, therefore, of special interest to all WiMAX equipment makers and service providers. This chapter mainly discusses the key issues and design factors to be considered for scheduler design. Before discussing the scheduling disciplines in detail, the three main services-voice, video, and data are discussed. Understanding the nature of traffic classes gives an insight on how to design the scheduler to guarantee the service. Moreover, the capacity limitation of each service is analyzed not only for capacity planning but also for simulation validation purposes. Finally, we present a brief survey of recent scheduling research. We classify the proposed mechanisms based on the use of channel conditions. The goals of scheduling are to achieve the optimal usage of resources, to assure the QoS guarantees, to maximize goodput, and to minimize power consumption while ensuring feasible algorithm complexity and system scalability. The organization of this chapter, shown in Table 1, is as follow: In Section 1 we give an overview to WiMAX in order to give readers better understanding of WiMAX characteristics such as physical (PHY) and MAC. In Section 2 the capacity limitation of each service is analyzed not only for capacity planning but also for simulation validation purposes. Then, we emphasize key issues such as two-dimensional downlink mapping (Section 3) and bandwidth request mechanism (Section 4) in order to design the scheduling disciplines, and then we discuss the key factors that the scheduling designer needs to consider as well as a brief survey on WiMAX scheduling in Section 5. We revisit open issues and potential research areas in Section 6. Table 1: Structure of Chapter 1-Introduction: PHY and MAC, registration process-Capacity estimation-Downlink mapping-Bandwidth request mechanisms-QoS schedulers: channel-aware and channel-unaware-Conclusions and open research issues Table 2: …