ABSTRACT
IEEE 802.16, also widely known as WiMAX (Worldwide Interoperability for Microwave Access), is an emerging broadband wireless standard. The amendment 802.16e has been defined to support mobility and other extensions. Their seamless support over an efficient handover (HO) mechanism is vital to the success of WiMAX networks. This chapter first presents an overview of the IEEE 802.16 standard, followed by a survey of major related work proposed to enhance handover in 802.16. Then, we describe a promising cross-layer design of WIMAX HO, the FMIPv6 (Fast Mobile IPv6 Handoff Protocol), and our newly proposed improved scheme. The enhancement is achieved by adopting two features: reducing control messages and eliminating duplicated care-of-addresses. The resulting HO delay is therefore decreased, which also improves other QoS parameters. Next, we describe the evaluation of supporting video and voice-over-IP traffic over four cross-layer HO schemes: FMIPv6, two existing enhancements to FMIPv6, and the newly proposed scheme. We evaluate the HO delay, HO packet loss, network throughput; PSNR (Peak Signal to Noise Ratio) and MOS (Mean Opinion Score) for video quality; and R-factor and MOS for voice quality. We found that the proposed enhancement has achieved considerably improvement over the existing schemes, especially under heavy network conditions and fast mobility speed.
