| The evolution to the next generation mobile network has promised to bring wireless multimedia communications to the subscribers. However, before this becomes a reality, many issues have to be resolved. In this dissertation, the following problems in next generation mobile networks are identified and studied: distributed channel (bandwidth) allocation, reducing handoff call dropping rates, efficient medium access control and handoff rerouting.; First, a relaxed mutual exclusion problem is introduced to model the problem of distributed channel allocation. A general algorithm that guarantees relaxed mutual exclusion for a single resource is proposed and the necessary and sufficient conditions for the information structure are proven. Based on this theoretical foundation, issues in distributed channel allocation such as deadlock resolution, multiple channels, efficient information structures, fault tolerance and channel selection strategies, are further explored. Based on the results, a distributed channel allocation scheme is proposed and its performance is studied. Next, we investigate the issue of reducing handoff call dropping rates for different classes of multimedia services to different predefined values. The problem is addressed by a priority-based adaptive bandwidth reservation strategy, which makes reservations based on certain monitored network parameters. Meanwhile the problem of bandwidth efficiency is addressed in two aspects: (1) integrating efficient dynamic channel allocation schemes with reservation schemes and (2) allowing services with flexible bandwidth requirements to temporarily use idle channels. In addition, we examine medium access control (MAC) protocols for multimedia mobile networks, especially the problem of how to design a MAC protocol that provides short random access delay for mobile terminals with delay-sensitive and bursty applications. A novel protocol that uses collision as a useful information for random access is proposed. Lastly, the problem of handoff rerouting in wireless mobile ATM networks is studied. The fact that a mobile-to-mobile connection can become disjointed due to simultaneous handoff rerouting is discovered. Solutions following two approaches, namely pre-established tree based rerouting and cross-over switch based rerouting, are proposed. These solutions are shown to be able to avoid the disjointed connection problem with insignificant extra overheads. |
