Optimum Co-Design for Spectrum Sharing Between MIMO Radar & MIMO Communication Systems

Spectrum congestion in commercial wireless communications is a growing problem as high-data-rate applications become prevalent. In an effort to relieve the problem, US federal agencies intend to make available spectrum in the 3.5 GHz band, which was primarily used by federal radar systems for surveillance and air defense, to be shared by both radar and communication applications. Even before the new spectrum is released, high UHF radars overlap with GSM communication systems, and S-band radars partially overlap with Long Term Evolution (LTE) and WiMax systems. When communication and radar systems overlap in the frequency domain, they exert interference to each other.
Spectrum sharing is a new line of work that targets at enabling radar and communication systems to share the spectrum efficiently by minimizing interference effects. The current literature on spectrum sharing includes approaches which either use large physical separation between radar and communication systems, or optimally schedule dynamic access to the spectrum by using OFDM signals, or allow radar and communication system to co-exist in time and frequency via use of multiple antennas at both the radar and communication systems. The latter approach greatly improves spectral efficiency as compared to the other approaches. This talk presents our recent work on the latter approach. In particular, we discuss optimal co-design of MIMO radar and MIMO communication system signaling schemes, so that the effective interference power to the radar receiver is minimized, while a desirable level of communication rate and transmit power are maintained.