Abstract
Wireless mesh networking technology is currently receiving a great deal of attention because it offers a promising solution to the challenges presented by next generation networks. In this dissertation, the Infrastructure/Backbone Wireless Mesh Network with access tier that connects the client wireless device to a mesh node and the backhaul tier that interconnects the mesh nodes to forward traffic to and from wireline Internet entry points or gateway mesh nodes is considered. To fulfill the quality of service guarantee in the two-tier wireless mesh access networks, different issues on the access and backhaul tier are addressed. In the access tier, we propose a new per-CLAss Flow fixed proportional differentiated service model (CLAF) and a companioning medium access control scheme for multi-service wireless LANs (WLANs), based on the IEEE 802.11 framework. Different from conventional differentiated services, CLAF provides a) policy-based fixed proportional differentiated service; b) such fixed proportional service differentiation is on per-class flow basis; and c) each class contention window size is adjusted to reflect the actual traffic load of the class. In the backhaul tier, we analyze how the multi-hop hidden terminal and exposed terminal problems affect the TCP throughput performance in multi-hop wireless networks via simulations. It shows that the performance interference due to the hidden and exposed terminal problems between wireless links is location-dependent. Therefore, based on the spatial reuse properties and considering the asymmetric traffic load of TCP connections, we propose spatial TDMA scheduling algorithm to resolve channel access contentions and thus improve the TCP performance in multi-hop wireless networks. The simulation results show that the proposed spatial TDMA scheduling algorithm can achieve better throughput performance. Since there is no channel interference within wireless links, the end-to-end TCP throughput is limited by the available bandwidth as expected.