Large-scale ad hoc networks with rate-limited infrastructure: Information-theoretic operating regimes

The impact and information-theoretic limits of infrastructure support with rate-limited wired links are analyzed in hybrid ad hoc networks, where multi-antenna base stations (BSs) are deployed and the rate of each BS-to-BS link scales at an arbitrary rate relative to the number of randomly located wireless nodes. For the operating regimes with respect to the number of BSs and the number of antennas per BS, we first analyze the minimum rate of each BS-to-BS link, C_bs, required to guarantee the capacity scaling for the network using infinite-capacity backhaul links. We then identify the operating regimes in which the required rate C_Bs scales much slower than 1. We also show the achievable throughput scaling for the case where the rate of each BS-to-BS link scales lower than C_Bs.

I. Introduction

In [1], the sum-rate scaling was introduced and characterized in a large wireless ad hoc network. It was shown that for the network having source–destination (S–D) pairs randomly distributed in a unit area, the total throughput scales as .¹

We use the following notation: i) means that there exist constants and such that for all , ii) means that , iii) if , iv) if , and v) if and [2].

This throughput scaling is achieved by conveying packets in a multihop (MH) fashion. In [3], the throughput scaling was improved to an almost linear scaling, i.e., , by using a hierarchical cooperation (HC) strategy for an arbitrarily small . Besides the HC scheme, there has been much research to improve the throughput of interference-limited networks up to a linear scaling by using node mobility [4], interference alignment [5], and infrastructure support [6], [7]. Especially for a hybrid network consisting of both wireless ad hoc nodes and infrastructure nodes, or equivalently base stations (BSs), where each BS is equipped with multiple antennas, the optimal capacity scaling was characterized in [7]—the achievability result is based on using one of infrastructure-supported single-hop (ISH) routing, infrastructure-supported MH (IMH) routing, pure MH transmission, and HC strategy.