Effect of Joint Cooperation and Multi-Hopping on the Capacity of Wireless Networks

The problem of communication among nodes in an extended network is considered, where radio power decay and interference are limiting factors. It has been shown previously that, with simple multi-hopping, the achievable total communication rate in such a network is at most Theta(radic(N)). In this work, we study the benefit of node cooperation in conjunction with multi-hopping on the network capacity. We propose a multi-phase communication scheme, combining distributed MIMO transmission with multi-hop forwarding among clusters of nodes. We derive the network throughput of this communication scheme and determine the optimal cluster size. This provides a constructive lower bound on the network capacity. We first show that in regular networks a rate of omega(N^2/3) can be achieved with transmission power scaling of Theta(N^alpha/6-1/3), where alpha > 2 is the signal path-loss exponent. We further extend this result to random networks, where we show a rate of omega(N^2/3 (logN) ^2-alpha/6 ) can be achieved with transmission power scaling of Theta(N^alpha/6-1/3 (logN) ^{(alpha-2) 2 /6}. In particular, as alpha approaches 2, only constant transmission power is required.