| Summary: | 博士 === 國立中山大學 === 資訊工程學系研究所 === 96 === Mobile ad hoc networks are without centralized infrastructure, and suitable for the region that difficultly builds the basic network framework, for example, desert and ocean. The bandwidth in mobile ad hoc networks is likely to remain a scarce resource. A call request of a connection in a wireless network is blocked if there exits no bandwidth route. This blocking does not mean that the total system bandwidth capacity is less than the request, but that there is no path in which each link has enough residual unused bandwidth to satisfy the requirement. Like the routing in a datagram network, if packets of a virtual circuit can stream across multiple paths, we can select multiple bandwidth routes such that the total bandwidth can meet the requirement of a source-destination pair. Therefore, even though there is no feasible single path for a bandwidth-constrained connection, we may still have a chance to accept this one if we can find multiple bandwidth routes to meet the bandwidth constraint. In this dissertation, we propose a bandwidth-constrained routing algorithm to aggregate the bandwidth of multiple wireless links by splitting a data flow across multiple paths at the network layer. That is, it allows the packet flow of a source-destination pair to be delivered over multiple bandwidth routes with enough overall resources to satisfy a certain bandwidth requirement. Our algorithm considers not only the QoS requirement, but also the cost optimality of the routing paths to improve the overall network performance. Extensive simulations show that high call admission ratio and resource utilization are achieved with modest routing overheads. This algorithm can also tolerate the node moving, joining, and leaving.
We also propose an algorithm, named efficient utilization polling (EUP), to support asynchronous data traffic at MAC layer by using the characteristics of Bluetooth technology. The algorithm uses a single bit in the payload header to carry the knowledge of queues in slaves for dynamically adapting the polling intervals for achieving the goals of high channel utilization and power conserving. In addition, we propose a differentiation mechanism, named shift-polling window (SPW). Based on EUP, the SPW differentiates the throughput from various classes, and still keeps the link utilization high and almost the same as that of the best-effort services. Extensive simulations are experimented on the behavior of the EUP and SPW by tuning the related parameters, such as polling interval, buffer size, and queue threshold level, etc., in order to verify the expectation of these methods.
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