Downlink Capacity of Hybrid Cellular Ad Hoc Networks

Augmenting cellular networks with shorter multihop wireless links that carry traffic to/from a base station can be expected to facilitate higher rates and improved spatial reuse, therefore potentially yielding increased wireless capacity. The resulting network is referred to as a hybrid network. However, while this approach can result in shorter range higher rate links and improved spatial reuse, which together favor a capacity increase, it relies on multihop forwarding, which is detrimental to the overall capacity. In this paper, our objective is to evaluate the impact of these conflicting factors on the overall capacity of the hybrid network. We formally define the capacity of the network as the maximum possible downlink throughput under the constraint of max-min fairness. We analytically compute the capacity of both one- and two-dimensional hybrid networks with regular placement of base stations and users. While almost no capacity benefits are possible with linear networks due to poor spatial reuse, significant capacity improvements with two-dimensional networks are possible in certain parametric regimes. Our simulations also demonstrate that in both cases, if the users are placed randomly, the behavioral results are similar to those with regular placement of users.