Improved Capacity Scaling in Wireless Networks With Infrastructure

摘要

This paper analyzes the impact and benefits of infrastructure support inimproving the throughput scaling in networks of $n$ randomly located wirelessnodes. The infrastructure uses multi-antenna base stations (BSs), in which thenumber of BSs and the number of antennas at each BS can scale at arbitraryrates relative to $n$. Under the model, capacity scaling laws are analyzed forboth dense and extended networks. Two BS-based routing schemes are firstintroduced in this study: an infrastructure-supported single-hop (ISH) routingprotocol with multiple-access uplink and broadcast downlink and aninfrastructure-supported multi-hop (IMH) routing protocol. Then, theirachievable throughput scalings are analyzed. These schemes are compared againsttwo conventional schemes without BSs: the multi-hop (MH) transmission andhierarchical cooperation (HC) schemes. It is shown that a linear throughputscaling is achieved in dense networks, as in the case without help of BSs. Incontrast, the proposed BS-based routing schemes can, under realistic networkconditions, 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 inthe 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), thereceived signal power can be larger than that of the HC, enabling a betterthroughput scaling under extended networks. Furthermore, by deriving thecorresponding information-theoretic cut-set upper bounds, it is shown underextended networks that a combination of four schemes IMH, ISH, MH, and HC isorder-optimal in all operating regimes.