Routing and Traffic-engineering in Multi-hop Wireless Networks: an Optimization Based Approach

Multi-hop wireless networks (MHWNs) attract significant interest due to the minimal infrastructure demands and their potential in supporting mobile and pervasive computing. The high demand placed by a growing user base on the limited available bandwidth places a premium on effective communication and networking for MHWNs. Recent studies in protocol development have improved the network performance considerably. However, effective networking under sparse bandwidth remains a difficult problem. Traffic-engineering techniques have been used to solve this problem in conventional networks. One of the key challenges in traffic-engineering in MHWNs is the routing problem – a problem of delivering packets across multiple wireless hops, considering the complex interference patterns and interactions in MHWNs. The dissertation targets developing a formally grounded approach for solving routing problems in MHWNs, while taking into account the effects of interference. The work builds on recent efforts in the networking community to express a network behavior as an optimization problem, and decomposing the formulation to provide distributed protocols. A successful model can then be applied to: (1) analyze the performance and capacity of existing protocols; (2) develop protocols for traffic engineering and admission for static networks; and (3) develop formally grounded and near-optimal distributed routing protocols. In MHWNs, the routing problem is substantially more complicated than the wired problem because of interference. Interference is exhibited at many levels, leading to effects such as uncontrolled contention and unfairness. The approach proposed in this dissertation breaks the problem into multiple layers. Firstly, a Multi-commodity flow based routing model that produces interferenceseparated routes is developed. The study analyzes the interaction of multiple routes and proposes effective objective functions to improve the throughput and delay metrics of the connections. Simulation results show significant improvement in performance over a traditional routing protocol. However, the assumption of an ideal scheduling model in the routing model discounts for the scheduling effects, that limits the applicability of the model. Existing accurate CSMA scheduling