I. Introduction
In ad hoc networks where a number of wireless nodes communicate with each other with no infrastructure support, the capacity scaling law for Gaussian channels was first studied in [1]. It was shown that the aggregate throughput scales as in a large wireless network where nodes are randomly located in a unit area.
We use the following notation: i) means that there exist constants and such that for all . ii) if . iii) if and .
This throughput scaling is achieved in such a way that data is delivered from a node to another node in a multihop fashion. The almost linear scaling law for an arbitrarily small was then derived using a hierarchical cooperation scheme [2] in the Gaussian network model. As an alternative approach to improving the total throughput up to a linear scaling, infrastructure nodes, or equivalently base stations (BSs), can be added to the wireless ad hoc network [3], [4]. In [5], a more general hybrid network where multiple antennas are deployed at each BS was studied. It was shown in [5] that using one of BS-supported single-hop routing, BS-supported multihop routing, pure multihop routing [1], and hierarchical cooperation [2] is needed to achieve the optimal capacity scaling law in the general hybrid network based on Gaussian channel models.