Capacity of Hybrid Cellular-Ad Hoc Data Networks

Abstract

In this paper, towards improving spatial reuse in a cellular network, we consider augmenting it with wireless ad hoc connectivity. The coverage area of each base-station is reduced and the users that are within the area relay traffic to nodes outside the area; these users further relay data to more distant users within the cell. The resulting network is referred to as a hybrid network. While this approach can result in shorter range higher-rate links and improved spatial reuse which, together favor a capacity increase, it relies on multi-hop forwarding which is detrimental to the overall capacity. Our objective in this work is to evaluate the impact of these conflicting factors on the capacity of the hybrid network and determine if this capacity is higher than that of the original cellular network. We formally define the capacity of the network as the maximum possible downlink throughput under the conditions of max-min fairness. We analytically compute the capacity of a two-dimensional hybrid network with regular placements of base-stations (BSs) and users. We validate our analytical results via simulations. Our studies demonstrate that capacity improvements are possible in certain parametric regimes in which the penalty due to multi-hop relaying does not outweigh the gains due to spatial reuse and shorter higher-rate links. Our simulations also demonstrate that if the users are placed randomly, the behavioral results are similar to that with regular placements of users.

Capacity scaling of multihop cellular networks

“…where noise is ignored since we consider an interference dominated environment like in [7] [14]. Note that we can easily find that uplink transmissions in Step I can have the same lower bound on SINR as shown above, which implies that uplink and downlink transmissions can have the same transmission rate, too.…”

“…By fully exploiting the link rate variability, we try to find whether and how much ad hoc relay can help improve the network capacity. The most related work in the literature is by Law et al [7], which formulates the throughput of regular multihop cellular networks as an optimization problem and gives some numerical results. The derived throughput in [7] is an upper bound which is not necessarily achievable.…”

“…The most related work in the literature is by Law et al [7], which formulates the throughput of regular multihop cellular networks as an optimization problem and gives some numerical results. The derived throughput in [7] is an upper bound which is not necessarily achievable. While in this work, we obtain for the first time theoretical results on scaling capacity, and what we present is feasible throughput.…”

A continuous-space analytical approach for relay node placement in hybrid cellular and ad hoc networks

“…In [5], the authors evaluated a hybrid network by reducing the coverage of a BS and relaying the traffic outside this coverage area. They intended to determine whether this scheme could improve the total performance in terms of capacity.…”

“…This may lead to overall improvement in the cellular coverage as well as optimum capacity of the HN. Many such attempts have been made within this topic and relevant directions, for example [4].In [5], the authors evaluated a hybrid network by reducing the coverage of a BS and relaying the traffic outside this coverage area. They intended to determine whether this scheme could improve the total performance in terms of capacity.…”