Mobility Management In IEEE 802.16e

During the past decades, the mobile hand-held devices including cellular phones have become very popular. Currently, to provide both voice and high-bandwidth data services, new systems are being developed. Originally, IEEE 802.16 has been designed for fixed subscriber stations (SSs). On the other hand, the recently-developed IEEE 802.16e is an extension targeting at the service provisioning to the Mobile Subscriber Stations (MSSs). As part of the mobility extension, the 802.16e mainly defines two functions, namely, a handover procedure and a sleep-mode operation. I first introduce the sleep mode operation and handoffs defined in IEEE 802.16e briefly, then focus on the performance analysis of the sleep mode operation and the modification based on sleep mode and handoffs to achieve a better performance. My work is described as follows:1. We characterize the standardized sleep mode in IEEE 802.16e. And then we build the system models for the energy consumption and the average packet delay affected by sleep-mode using statistics. At last we give the simulation on the analytical results by MATLAB and a conclusion.2. Based on the characteristics of PSC types and the properties of data delivery service types, we proposed an efficient sleep mode management scheme. With guaranteed data transfer, the design of PSC parameters to maximize sleep windows and the usage of PSC anti-expansion mechanism to decrease the number of PSCs facilitate the lengthening of unavailability intervals. Accordingly, the energy of MS is saved greatly. The analysis and simulation results show that the proposed scheme can minimize the energy consumption of MS under the condition that the QoS requirements of connections are satisfied.3. We proposed a handoff scheme which exploits not only downlink signal but also uplink signal. In the conventional handoff schemes, only downlink signal is used to determine handoff initiation and execution. Thus, the downlink channel can be maintained in good quality when a MS moves to neighbor cells. On the other hand, the uplink channel quality can dramatically grow worse during handoff process because uplink channel quality can be different with downlink channel quality although TDD systems. To overcome this problem, the proposed scheme determines handoff execution and direction based on both of uplink and downlink signal. In addition, the proposed scheme triggers handoff process based on uplink signal and results in reduction of unnecessary scanning in non-handoff region. We evaluate the performance of the proposed scheme using computer simulation. The simulation results show that the proposed algorithm with joint hysteresis can reduce outage probability approximately 10% compared with the mobile assisted handoff in IEEE 802.16e.