Analysis of IEEE 802.16e contention-based handover in erroneous channel

The IEEE 802.16 standard for fixed and mobile broadband wireless access systems specifies a group of Medium Access Control (MAC) procedures among which the handover (HO) is one of the crucial contributions, especially significant for the mobility requirement. The HO procedure defines numerous parameters which need a fine tuning in order to achieve satisfactory communication performance. This paper presents the impact of handover parameters value and an error-prone radio channel over the IEEE 802.16e CDMA-based handover procedure performance. We analytically analyzed the handover latency and connection dropping probability. The results were compared with the experimental measurements conducted on a protocol prototype specially developed for this purpose by using Specification and Description Language. The following parameters were investigated: value of the contention window minimal and maximal size, number of transmission allocations per frame, number of available CDMA ranging codes, timers and maximum retransmission limits used in the processes of ranging, basic capabilities negotiation and registration. We have found that all these parameters need to be carefully adjusted in accordance to the following conditions: number of stations performing handover at a same time, WiMAX physical layer working parameters and frame-error rate in the uplink and downlink radio channel.