On the Broadcast Capacity of Wireless Networks

A fundamental problem in wireless networks is determining the broadcast capacity, i.e. the maximum data transfer rate from a given node to every other node in a relay network. This problem becomes more important as many network protocols rely on broadcast of certain control messages. In this paper, the scaling of the broadcast capacity with the number of nodes (N ) in the network is studied. In the highdensity regime (i.e. the node density goes to infinity; the network area is fixed), it is shown that the broadcast capacity is upper bounded by Θ(log N). Schemes are provided that achieve i) Θ(log N) throughput if the channel fading is spatially continuous; ii) Θ(log log N) throughput if the channel fading is spatially i.i.d.. The reasons for this drastic reduction in throughput and the connections with multiuser diversity are discussed. Analogous results are provided for the extended-network model (i.e. the node density is fixed; the network area goes to infinity).