Channel assignment, routing and cross layer issues for multi-radio multi-channel wireless mesh netorks

Abstract

Next generation wireless mobile communications will be driven by converged networks that integrate disparate technologies and services. The Wireless Mesh Network (WMN) is envisaged to be one of the key components in the converged networks of the future, providing flexible, high-bandwidth wireless backhaul over large geographical areas. While single radio mesh nodes, operating on a single channel suffer from capacity constraints, equipping mesh routers with multiple radios using multiple non-overlapping channels can significantly alleviate the capacity problem and increase the aggregate bandwidth available to the network. However, the assignment of channels to the radio interfaces poses significant challenges. The goal of channel assignment algorithms in multi-radio mesh networks is to minimize interference while improving the aggregate network capacity and maintaining the connectivity of the network. In this thesis, we examine the unique constraints of channel assignment in wireless mesh networks and identify the key factors governing assignment schemes, with particular reference to interference, traffic patterns, and multipath connectivity. After presenting a taxonomy of existing channel assignment algorithms for WMNs, we describe a new channel assignment scheme, called MesTiC, which incorporates the mesh traffic pattern together with connectivity issues in order to minimize interference in multi-radio mesh networks. In a second part of this thesis, we consider that a paradigm shift from the classic routing schemes is needed. Usual approaches are not always satisfactory since they often use shortest-path heuristic and tend to concentrate transmissions to certain nodes. To efficiently exploit the presence of multiple channels instead, a proper routing algorithm should avoid congested links and possibly make use of an estimation of the actual network traffic. Therefore, cross-layer information exchange can be useful for an efficient functioning of the routing protocols. We analyze all these issues and propose and identify possible solutions.