Network-Decomposed Hierarchical Cooperation in Ad Hoc Networks with Social Relationships

In this paper, we introduce a network-decomposed hierarchical cooperation (HC) protocol and completely characterize the corresponding throughput-delay tradeoff for a large wireless ad hoc network formed in the context of social relationships. Instead of randomly picking source-destination pairings, we first consider a distance-based social formation model characterized by the social group density γ and the number of social contacts per node q where the probability that any two nodes in distance d away from each other are socially connected is assumed to be proportional to d^-γ , which is a feasible scenario. Then, using muiltihop and network-decomposed HC protocols under our social formation model, we analyze a generalized throughput-delay tradeoff according to the operating regimes with respect to parameters γ and q in both a dense network of unit area and an extended network of unit node density via a non-straightforward network transformation strategy. Our main results reveal that as γ increases, performance on the throughput-delay tradeoff can remarkably be improved, compared to the network case with no social relationships. It is also shown that in the dense network, the network-decomposed HC protocol always outperforms the multihop protocol, while the superiority of the network-decomposed HC depends on γ and the path-loss exponent in the extended network.