Transmission Capacity of Ad-hoc Networks with Multiple Antennas using Transmit Stream Adaptation and Interference Cancelation

TL;DR

This paper analyzes the transmission capacity of ad-hoc networks with multiple antennas, deriving bounds and optimal strategies for data streams and interference cancelation to maximize network density under outage constraints.

Contribution

It introduces bounds and optimal configurations for multiple antenna use in ad-hoc networks, considering beamforming and interference cancelation techniques.

Findings

Single data stream transmission is optimal with beamforming and interference cancelation.

Using all but one SRDOF for interference cancelation maximizes capacity with beamforming.

Fractional SRDOF use for cancelation is optimal without beamforming.

Abstract

The transmission capacity of an ad-hoc network is the maximum density of active transmitters per unit area, given an outage constraint at each receiver for a fixed rate of transmission. Assuming that the transmitter locations are distributed as a Poisson point process, this paper derives upper and lower bounds on the transmission capacity of an ad-hoc network when each node is equipped with multiple antennas. The transmitter either uses eigen multi-mode beamforming or a subset of its antennas to transmit multiple data streams, while the receiver uses partial zero forcing to cancel certain interferers using some of its spatial receive degrees of freedom (SRDOF). The receiver either cancels the nearest interferers or those interferers that maximize the post-cancelation signal-to-interference ratio. Using the obtained bounds, the optimal number of data streams to transmit, and the optimal SRDOF to use for interference cancelation are derived that provide the best scaling of the transmission capacity with the number of antennas. With beamforming, single data stream transmission together with using all but one SRDOF for interference cancelation is optimal, while without beamforming, single data stream transmission together with using a fraction of the total SRDOF for interference cancelation is optimal.