MAC LAYER AND ROUTING PROTOCOLS FOR HETEROGENEOUS AD HOC NETWORKS: ROUTING IN HETEROGENEOUS AD HOC NETWORKS WITH ASYMMETRIC LINKS AND PERFORMANCE EVALUATION STUDIES

In a heterogeneous ad hoc network, assorted devices with different computation and communication capabilities co-exist and the links are asymmetric. Most MAC layer and routing protocols for ad hoc networks routinely assume that all links are symmetric and are unable to exploit the asymmetric links present in a network, thus leading to an inefficient bandwidth utilization, or, in the worst case, to lack of connectivity. To exploit the asymmetric links, the protocols must deal with the asymmetry of the path from a source node to a destination node which affects either the delivery of the original packets, or the paths taken by acknowledgments, or both. Furthermore, the hidden node problem requires a more careful analysis in the case of asymmetric links. We conclude that MAC layer and routing protocols capable of using asymmetric links are more complex than traditional ones, but can improve the connectivity, and provide better performance. We are confident that approximate results for various performance metrics of wireless networks obtained using time-parallel simulation are sufficiently accurate and able to provide the necessary insight into the inner workings of the protocols.