The design and evaluation of efficient routing and quality of service support for wireless ad-hoc networks.

摘要

Routing and QoS in ad-hoc networks are important research issues that result from node mobility and absence of a fixed infrastructure. Routing protocols need to react promptly to frequent network topology changes that occur due to node mobility and link outages. Besides node mobility, typical characteristics of ad-hoc networks such as limited bandwidth, limited power supply and high link error rate pose additional challenges while designing routing protocols and achieving desired QoS.; In this dissertation, we present our work toward the support of efficient routing, QoS and TCP performance enhancement for ad-hoc networks. Requirements during our design include high accuracy in terms of operations, high efficiency in terms of data transfer rates, low overhead in terms of bandwidth and providing end-to-end QoS. The main contribution of our research is the design of new on-demand routing protocols to meet the desired criteria and to demonstrate their superior performance. These protocols are known as Signal Power Adaptive Fast Rerouting (SPAFAR) and Adaptive Dispersity QoS Routing (ADQR).; We propose a route discovery algorithm to find multiple disjoint paths, where longer lived paths are found and selected for data transfer. A longer-lived path is defined as a path which keeps longer duration of connectivity between a source and destination. Multiple disjoint paths provide dispersed data transfer and resource reservation, resulting in an increase of the effective bandwidth utilization, reduction of congestion and the probability of dropped packets, and support of end-to-end QoS. A longer-lived path generally involves less route maintenance. Less route maintenance generates less control packets, resulting in an increase of bandwidth efficiency for data transfer. We also propose a fast rerouting algorithm to significantly reduce data flow and QoS disruptions. Rerouting is proactively carried out before path unavailability occurs. Multiple paths provided by the route discovery phase significantly reduce the delay in finding an alternate path.; A simulation study is carried out where the performance of our protocols are compared with several other routing algorithms. Simulation results show that our protocols involve less control overhead, reduce data flow disruptions, provide end-to-end QoS and improve TCP performance, by providing efficient route discovery and maintenance mechanisms.