Massive MIMO for Wireless Sensing with a Coherent Multiple Access Channel

TL;DR

This paper analyzes the use of massive MIMO at a wireless sensor network's fusion center for detecting Gaussian signals, showing how detection performance scales with the number of antennas and sensor power, with different strategies for CSI-dependent and independent detectors.

Contribution

It provides new insights into the asymptotic detection performance and optimal gain design in massive MIMO-enabled wireless sensing, including bounds and scaling laws.

Findings

NP detector performance remains constant with increasing antennas if power scales down.

Energy detector's deflection can be maintained with power scaling as inverse square root of antennas.

Multi-antenna energy detector outperforms single-antenna at high sensor power.

Abstract

We consider the detection and estimation of a zero-mean Gaussian signal in a wireless sensor network with a coherent multiple access channel, when the fusion center (FC) is configured with a large number of antennas and the wireless channels between the sensor nodes and FC experience Rayleigh fading. For the detection problem, we study the Neyman-Pearson (NP) Detector and Energy Detector (ED), and find optimal values for the sensor transmission gains. For the NP detector which requires channel state information (CSI), we show that detection performance remains asymptotically constant with the number of FC antennas if the sensor transmit power decreases proportionally with the increase in the number of antennas. Performance bounds show that the benefit of multiple antennas at the FC disappears as the transmit power grows. The results of the NP detector are also generalized to the linear minimum mean squared error estimator. For the ED which does not require CSI, we derive optimal gains that maximize the deflection coefficient of the detector, and we show that a constant deflection can be asymptotically achieved if the sensor transmit power scales as the inverse square root of the number of FC antennas. Unlike the NP detector, for high sensor power the multi-antenna ED is observed to empirically have significantly better performance than the single-antenna implementation. A number of simulation results are included to validate the analysis.