Maximum Throughput in Multiple-Antenna Systems

TL;DR

This paper derives the maximum throughput and expected-rate for multiple-antenna channels under Rayleigh fading with limited transmitter CSI, identifying optimal transmission strategies and analyzing various antenna configurations.

Contribution

It provides new analytical expressions and optimal strategies for maximizing throughput and expected-rate in MISO and MIMO channels with partial CSI, including low/high SNR regimes.

Findings

Optimal strategy in MISO: use all antennas with equal power and uncorrelated signals.

Closed-form expression for maximum continuous-layer expected-rate in MISO channels.

Distributed antenna system has same throughput as a 2x1 MISO channel.

Abstract

The point-to-point multiple-antenna channel is investigated in uncorrelated block fading environment with Rayleigh distribution. The maximum throughput and maximum expected-rate of this channel are derived under the assumption that the transmitter is oblivious to the channel state information (CSI), however, the receiver has perfect CSI. First, we prove that in multiple-input single-output (MISO) channels, the optimum transmission strategy maximizing the throughput is to use all available antennas and perform equal power allocation with uncorrelated signals. Furthermore, to increase the expected-rate, multi-layer coding is applied. Analogously, we establish that sending uncorrelated signals and performing equal power allocation across all available antennas at each layer is optimum. A closed form expression for the maximum continuous-layer expected-rate of MISO channels is also obtained. Moreover, we investigate multiple-input multiple-output (MIMO) channels, and formulate the maximum throughput in the asymptotically low and high SNR regimes and also asymptotically large number of transmit or receive antennas by obtaining the optimum transmit covariance matrix. Finally, a distributed antenna system, wherein two single-antenna transmitters want to transmit a common message to a single-antenna receiver, is considered. It is shown that this system has the same outage probability and hence, throughput and expected-rate, as a point-to-point $2\times 1$ MISO channel.