Existence of data and multiuser diversities in noncooperative mobile infostation networks

The capacity of mobile Infostation network can be greatly increased, if, in addition to direct short-range communications between mobile nodes and fixed infostations, nodes also communicate amongst themselves whenever they meet. However, this requires cooperation among mobile nodes that are not necessarily spontaneous for commercial applications. We propose means to create opportunistic cooperation In the context of contention distribution in selfish mobile infostatlon networks. First, we assume that all nodes have a common interest in all files. We stipulate a social contract such that a bilateral file exchange takes place only when either node obtains something it wants from the exchange. Resulting capacity depends on mobility, the number of files being disseminated, and node density. In addition to the existence of multiuser diversity, our results indicate the existence of data diversity - throughput increases as the number of files of Interest to all nodes increases. We also consider the case where nodes have dissimilar interests. Results show that as the level of Interest overlap decreases, network performance degrades dramatically. We propose an alternate user strategy in the partially overlapping-lnterests case and show that network throughput is significantly improved by allowing better use of multiuser diversity. We conclude that through opportunistic cooperation, both data and multiuser diversities exist in noncooperative mobile infostation networks.