Asymmetric MIMO System Design Based on OFDMA-TDD for Unmanned Ground Systems

Abstract

The unmanned ground system (UGS) demands the high data rate and link reliability in battlefield and hazardous environment. Also, more radio resources should be allocated in the uplink channel for the surveillance data than in the downlink channel, unlike the commercial communication system where the utilization of resources is biased toward the downlink to provide the multimedia service to the multiple users. In this paper, considering the traffic unbalance between the uplink and downlink of UGS, we propose an appropriate frame structure for UGS based on the orthogonal frequency division multiplexing (OFDM) and time division duplex (TDD). In addition, a power control method for UGS is proposed to guarantee the stable communication link for the downlink, uplink, and ad-hoc channel. Finally, in order to evaluate the performance of the proposed system, we design and implement the asymmetric MIMO system with space time block code (STBC), spatial multiplexing method and modified maximum likelihood (MML) decoding scheme. We perform the field test in the long-range and line-of-sight (LoS) environment. It is verified that implemented system for UGS can support the high- speed data transmission and maintain the robust link.