  This paper analyzes the impact and benefits of infrastructure support in
improving the throughput scaling in networks of $n$ randomly located wireless
nodes. The infrastructure uses multi-antenna base stations (BSs), in which the
number of BSs and the number of antennas at each BS can scale at arbitrary
rates relative to $n$. Under the model, capacity scaling laws are analyzed for
both dense and extended networks. Two BS-based routing schemes are first
introduced in this study: an infrastructure-supported single-hop (ISH) routing
protocol with multiple-access uplink and broadcast downlink and an
infrastructure-supported multi-hop (IMH) routing protocol. Then, their
achievable throughput scalings are analyzed. These schemes are compared against
two conventional schemes without BSs: the multi-hop (MH) transmission and
hierarchical cooperation (HC) schemes. It is shown that a linear throughput
scaling is achieved in dense networks, as in the case without help of BSs. In
contrast, the proposed BS-based routing schemes can, under realistic network
conditions, improve the throughput scaling significantly in extended networks.
The gain comes from the following advantages of these BS-based protocols.
First, more nodes can transmit simultaneously in the proposed scheme than in
the MH scheme if the number of BSs and the number of antennas are large enough.
Second, by improving the long-distance signal-to-noise ratio (SNR), the
received signal power can be larger than that of the HC, enabling a better
throughput scaling under extended networks. Furthermore, by deriving the
corresponding information-theoretic cut-set upper bounds, it is shown under
extended networks that a combination of four schemes IMH, ISH, MH, and HC is
order-optimal in all operating regimes.
