The Multicast Capacity Region of Large Wireless Networks

We study the problem of determining the multicast capacity region of a wireless network of n nodes randomly located in an extended area and communicating with each other over Gaussian fading channels. We obtain an explicit information-theoretic characterization of the scaling of the multicast capacity region for n nodes in terms of 2n weighted cuts. These cuts only depend on the geometry of the locations of the source nodes and their destination nodes and the traffic demands between them, and thus can be readily evaluated. The results are constructive and provide a two-layer architecture for achieving nearly the entire multicast capacity region in the scaling sense: The top layer routes traffic from each of the source nodes to its set of destination nodes, and the bottom layer physically distributes/concentrates traffic among appropriate nodes through one of the two cooperative communication schemes - hierarchical relaying and multi-hopping - depending on the wireless-channel characteristics.