Virtual MIMO Wireless Sensor Networks: Propagation Measurements and Fusion Performance

In this paper, we investigate the practical implications of employing virtual multiple-input multiple-output (MIMO) systems for prototyping future-generation wireless sensor networks (WSNs), especially in the light of recently proposed distributed detection based decision fusion (DF) rules. In order to do that, an indoor-to-outdoor measurement campaign has been conducted recently for investigating the propagation characteristics of an 8 × 8 virtual MIMO system. The campaign is conducted with transmit antennas representing the sensors deployed in different indoor environments and receiver antennas mounted on an outside tower representing the DF center. Channel measurements are reported when a 20 MHz wide signal is transmitted at 2.53 GHz. Measurements are collected for different spatial combinations of the transmit antennas. After analyzing the collected data, the performance of different DF rules is compared and tested over the measured channel. The results show that the fusion rules perform differently over different sets of measured channels. The results obtained here are important for maximizing performance and enabling the air-interface design of next-generation WSNs.