MIMO radar waveform design for coexistence with cellular systems

The design of multiple-input multiple-output (MIMO) radar waveforms with specified properties has a number of applications including clutter suppression and interference mitigation. In this paper, we design radar waveforms with the aim to mitigate radar interference to communication system. We design constant envelope (CE) transmit beampattern of a MIMO radar, when it is sharing its spectrum with a cellular system, with the constraint that the waveform is in the null space of interference channel between radar and communication system. We design the desired beampattern by unconstrained nonlinear optimization of the desired covariance matrix. We consider waveform design problem for a stationary maritime MIMO radar when interference channels are changing slowly and thus they can be included in the beampattern matching optimization problem. In addition, we also consider the case when the maritime MIMO radar is moving and thus experiences interference channels that are changing fast enough to be not included in the optimization problem. For this case, we design the CE waveform first and then project it onto the null space of interference channel, before transmission, in order to have zero interference to the communication system. We demonstrate, through simulations, the effect of including the constraint of spectrum sharing or the waveform be in the null space of interference channel on the CE waveform design.