Open-Loop Spatial Multiplexing and Diversity Communications in Ad Hoc Networks

TL;DR

This paper analyzes open-loop multi-antenna communication schemes in ad hoc networks, deriving formulas for performance metrics and showing multi-antenna setups can outperform single-antenna networks with simple MAC protocols.

Contribution

It provides new closed-form expressions for outage probability, throughput, and capacity in ad hoc networks using multi-antenna schemes with slotted ALOHA.

Findings

Multi-antenna schemes can outperform single-antenna networks in practical scenarios.

Optimal number of transmit antennas depends on network parameters.

Performance varies with node density and SIR operating point.

Abstract

This paper investigates the performance of open-loop multi-antenna point-to-point links in ad hoc networks with slotted ALOHA medium access control (MAC). We consider spatial multiplexing transmission with linear maximum ratio combining and zero forcing receivers, as well as orthogonal space time block coded transmission. New closed-form expressions are derived for the outage probability, throughput and transmission capacity. Our results demonstrate that both the best performing scheme and the optimum number of transmit antennas depend on different network parameters, such as the node intensity and the signal-to-interference-and-noise ratio operating value. We then compare the performance to a network consisting of single-antenna devices and an idealized fully centrally coordinated MAC. These results show that multi-antenna schemes with a simple decentralized slotted ALOHA MAC can outperform even idealized single-antenna networks in various practical scenarios.