MIMO functionality for Legacy Radios

ABSTRACT:Multiple-input, multiple-output (MIMO) RF systems are revolutionizing the RF communications industry by transforming historically problematic, heavily faded RF environments into rich, multi-channel media data rates enhanced by factors of 2-4X or more. Although the air-air datalink scenario does not enjoy the rich multipath environments that are exploited by commercial and military MIMO systems, many of the salient features of MIMO can be applied to airborne directional datalink systems to great effect. In this program, we investigate three MIMO-related enhancements that are applicable to any distributed aperture airborne data link system. The three techniques to be studied include orthogonal polarization in the Tx/Rx antenna to upgrade link capacity, utilization of multiple antenna arrays in receive mode, and inclusion of a novel fast-search methodology to reduce discovery time. Numerous existing directional datalink systems incorporate multiple high-gain antenna arrays which provide a strong base for significant MIMO-inspired capability enhancements with the introduction of the proposed applique. All three of our proposed concepts have great potential to enhance the capacity, robustness, and other performance aspects of legacy distributed datalink systems without requiring changes to the current radio or waveform.BENEFIT:Although FIRST RFs proposed investigation is focused on legacy airborne datalinks, the technology has direct applicability to other applications that utilize distributed antennas. These technologies provide a path to improve ground tactical systems as well. The system provides several key benefits including increased (ideally double) link capacity and data rates to support larger networks and greater throughput for ISR, heavily cooperative, and other data-intensive missions. Elegant signal combination results in a more robust system that achieves improved signal-strength links without dropouts as nodes change in bearing with one another (switch loss). A fast, LPI/LPD, ad-hoc in-flight network reconfiguration is achieved using a novel discovery approach improving reassignments and other reconfiguration requirements imposed by the mission. With these potential benefits, the applicability of this technology extends beyond the scope of airborne directional datalink systems and has other military as well as commercial applications. FIRST RF looks forward to working with Air Force to explore the applicability of this technology to the near-term need for datalink missions.