Interference alignment based precoder-decoder design for radar-communication co-existence

Co-existence of radar and communication systems is necessary to facilitate new wireless systems and services due to shortage of useful radio spectrum. Moreover, changes in spectrum regulation will be introduced where spectrum is allocated in larger chunks and different radio systems need to share the spectrum. For example LTE, WI-FI and 5G systems will have to share spectrum with S-band radars. Managing interference is a key task in spectrum sharing and co-existence. In this paper we propose a joint Precoder-Decoder design that maximizes SINRs for co-existing radar and communication systems. Multicarrier waveforms are assumed for both subsystems. Interference Alignment (IA) constraints are imposed to facilitate easier interference cancellation in finding the Precoder and Decoder. Therefore, a maximum Degree of Freedom (DoF) upper bound for K + 1 radar-communication users interference channel can be achieved. Our simulation studies demonstrate that the interference can be practically fully cancelled in both communication and radar systems. This leads to improved detection performance in radar and higher rate in communication subsystems. A significant performance gain over a subspace-based Precoder design is obtained as well.