Abstract
The IEEE 802.16j MR standard has been developed to provide performance enhancement to the existent IEEE 802.16e network. However, the issues such as frequent handoffs and low spectrum utilization which are not encountered in IEEE 802.16e may be incurred in IEEE 802.16j. The RS grouping is one optional mechanism in the IEEE 802.16j MR standard to overcome these problems. In the thesis, we are interested in investigating the RS grouping performance enhancement in terms of throughput and handoff frequency. Based on Random-Walk mobility model, this thesis designed a Handoff-Minimizing RS Grouping Algorithm by utilizing the grouping patterns resulting in lower handoff probability, that is the pattern with more inner-boundaries among the patterns with the same preferred group size. The simulation results show that the handoff frequency of the considered MR network can be minimized using our grouping algorithm when the preferred group size is given, and thus verify our theoretical analysis. In addition, we proposed two centralized scheduling policies, the throughput-first (TF) and the delay-first (DF) policies, which object to maximize the system throughput and minimize average delay, respectively. By integrating our RS grouping algorithm and centralized scheduling algorithm, the simulation results show that the throughput performance are gradually increased under both the TF and the DF policies while the considered group size increased, which is due to the lower packet loss from frequent handoffs problem. Moreover, we show that the DF policy not only can minimize the average delay, but also provide the fairness property among different loaded users.