Monitoring Radiated Coexistence Testing Using GMM-Based Classifier

Abstract

Sharing spectrum resources in unlicensed bands grants vehicular applications inexpensive and ubiquitous access to wireless services. However, wireless technology coexistence concerns are gaining increased attention. In response, coexistence test methods are now being reported in the literature, and novel solutions are considered in the American National Standards Institute C63.27 Standard for Evaluation of Wireless Coexistence. Furthermore, the IEEE 802 standards committee formed a new study group, named wireless automotive coexistence, operating under the umbrella of 802.19 working group to highlight the increasing concerns of wireless coexistence in the automotive domain. The radiated open environment coexistence test (ROECT) method offers high flexibility to test wireless devices for coexistence. Radio signal propagation during testing is over the air, reducing access to the signal path. Consequently, monitoring instantaneous device performance is a challenge yet to be addressed. This paper introduces a novel method for estimating the channel utilization of multiple, concurrent wireless transmitters sharing the 2.4-GHz ISM band in the context of ROECT. Passively received power measurements were collected during testing, and then a Gaussian mixture model was used to build a classifier for labeling observed power samples relative to their source. Case studies utilizing IEEE 802.11n as an interfering system with an under test system based on either IEEE 802.11n or ZigBee are detailed. Findings demonstrate the mutual effect of spectrum sharing on both interfering and under test systems in terms of per-second channel utilization and frame collision. Experimental results show an overall accuracy exceeding 98%.