Adaptive routing services in ad-hoc and sensor networks

In this dissertation, two different approaches are proposed to improve adaptability of routing services for mobile ad-hoc and sensor networks. For mobile ad-hoc networks, we propose a general approach called active ad-hoc network routing that uses a helper module to improve existing routing algorithms without changing their inner mechanisms. This helper module issues probing packets that roam around an ad-hoc network to collect information which then is used to update routing state. By collecting different state information, adaptability of existing ad-hoc network routing algorithms can be improved in multiple aspects. As a case study, we apply this general approach to the Dynamic Source Routing algorithm in ad-hoc networks. The resulting algorithm, called Active DSR, collects topology and queue-length information to update route cache in DSR. Discussions and extensive simulations show that routing cache miss rates are reduced by using the topology information, and network congestion is improved by using the queue-length information. We also show energy consumption and TCP performance improvement under ADSR. For sensor networks, we propose a new routing paradigm called X Visiting-pattern Routing (XVR) to promote routing flexibility. Visiting-patterns indicate where to forward packets as next hops in a network and are essential to any routing service. Unlike any existing routing service in which each packet handler is integrated with its visiting-pattern, XVR deliberately decouples visiting-patterns of packets from their corresponding packet handlers. The separated packet handlers consist of a routing core that calls the visiting-pattern module when issuing or forwarding packets. This separation has several important implications for building flexible routing services in sensor networks. First, a routing service can be changed by simply using different visiting-patterns with low energy cost. Second, extensive simulations show that existing and new routing services can be brought together for comprehensive experiments in a unified environment. Third, automatic and concurrent routing services can be built on top of XVR without changing the routing core. As a case study, we show how to conduct automatic routing changes between two known routing services, push and pull, with XVR, and evaluate performance gains.