HierHybNET: Capacity scaling of ad hoc networks with cost-effective infrastructure

In this paper, we introduce a large-scale hierarchical hybrid network (HierHybNET) consisting of both n wireless ad hoc nodes and m base stations (BSs) equipped with l multiple antennas per BS, where the communication takes place from wireless nodes to a remote central processor (RCP) through BSs in a hierarchical way. To understand a relationship between capacity and cost, we deal with a general scenario where m, l, and the backhaul link rate can scale at arbitrary rates relative to n (i.e., we introduce three scaling parameters). In order to provide a cost-effective solution for the deployment of backhaul links connecting BSs and the RCP, we first derive the minimum backhaul link rate required to achieve the same capacity scaling law as in the infinite-capacity backhaul link case. Assuming an arbitrary rate scaling of each backhaul link, a generalized achievable throughput scaling law is then analyzed. Moreover, three-dimensional information-theoretic operating regimes are explicitly identified according to the three scaling parameters. We also characterize an infrastructure-limited regime where the throughput is limited by the backhaul link rate.