Chapter 6 Routing , Interface Assignment and Related Cross-layer Issues in Multiradio Wireless Mesh Networks

Many technological standards for Wireless Mesh Networks include the possibility to use several nonoverlapping channels for data transmission. This represents an opportunity that can be exploited by equipping the terminals with multiple network interfaces. This opens up an interesting challenge, namely, how to simultaneously use different frequencies, so as to limit collisions and therefore activate multiple simultaneous transmissions in the same geographic area. At the same time, this poses new issues; for example, network connectivity is reduced, because nodes that do not interfere are also unable to communicate with each other. Thus, more complex interface management techniques are required. Moreover, a paradigm shift from the classic routing schemes is needed. Usual approaches are not always satisfactory because 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. In this chapter, we will analyze all these issues and propose and identify possible solutions.