Resolving Target Ambiguities in Automotive Radar Using DDMA Techniques

Doppler division multiple access (DDMA) is a slow-time phase coding technique that enables implementing multiple-input multiple-output (MIMO) radar using legacy phased-array hardware. However, DDMA is well known to cause ambiguity in the received Doppler spectrum. Although asymmetric DDMA has been proposed to mitigate the target ambiguity problem, it can result in collisions between different target reflections associated with different transmit antennas. In this paper, we introduce a method for resolving target ambiguities in DDMA-based automotive MIMO radar. The proposed method utilizes conventional DDMA with all transmit antennas except one. Simultaneously, a single slow-time channel that is independent from the DDMA code is used to resolve the target ambiguities. It is shown that the proposed system achieves an effective solution with little additional complexity with respect to the standard DDMA technique. Simulation examples are used to demonstrate the performance of the proposed method.