Multipath Routing Optimization in Wireless Mesh Networks

Multipath routing provides load balancing and fault tolerance by employing multiple paths to destination. The inherent mesh infrastructure of IEEE 802.11 based wireless mesh networks provide added support to construct multiple robust paths. However, based on geometric locations of wireless nodes, neighbourhood interference and channel contention, create challenges for multipath routing schemes. A large body of research has been carried out to maximize aggregate end-to-end throughput using multipath routing; however, interference has not been accurately modelled in majority of the work. Based on the relative location of transmitters and receivers, interfering links can be categorized as coordinated and non-coordinated. Compared to coordinated interference, information asymmetric non-coordinated interference introduces bottleneck links and signi?cantly reduces the aggregate throughput. The impact of this interference is even observed on links several hops away. The objective of this thesis is to improve network throughput by exploiting redundant mesh infrastructure of wireless mesh network using multipath routing which mitigates non-coordinated interference with priority. We propose Interference Avoidance based Multipath Routing Linear Programming (IAMR-LP) optimization model with an objective to maximize end-toend throughput by using multiple available paths, considering coordinated and non-coordinated interference. It employs topology control to avoid bottleneck links which are su?ering from severe non-coordinated interference. The model aims at selecting a subset of quality paths for each ?ow so that the aggregate end-to-end throughput is maximized. Selection of paths is constrained by per link capacity and interference at each link. The simulation throughput is 89% of the throughput achieved using numerical solution which shows the e?ectiveness of the model. Based upon the results of this model as baseline, we propose an Adaptive Multipath Routing Approach with Topology Control (AMRTC) that develops a multipath routing strategy to achieve better end-to-end throughput by purging badly a?ected non-coordinated links during path construction procedure. Extensive simulation-based evaluation shows that AMRTC outperforms the existing schemes in improving the network throughput, by upto a factor of 1.68. Next, we propose Interference Mitigation based Multipath Routing Mixed Integer Nonlinear Programming (IMMR-MINLP) model which avoids the link elimination approach of AMRTC and adjusts the ?ow rates of links to reduce the impact of multilevel non-coordinated interference. The numerical solution to the optimization problem generates multiple paths for ?ows, resulting in optimal network throughput for a given network and input tra?c load. The generated paths of the numerical solution are then fed in OPNET to simulate respective network instances. The evaluations of simulation with IMMR-MINLP model shows the e?ectiveness of the model which achieves upto 91% of the optimal aggregate network throughput. The comparison of the fairness index of IMMR-MINLP with existing schemes show its e?ectiveness in fair distribution of throughput among multiple ?ows. Finally, the performance improvement of IMMR-MINLP model is compared with LMX:M3F, MRAC, and ETT in terms of packet loss ratio, end-to-end delay and link utilization