Multiple Subbands Coherent Accumulation Target Detection Algorithm for DDMA-MIMO Radar

Compared with the traditional time division multiple access - multiple input multiple output (TDMA-MIMO) radar, Doppler division multiple access - multiple input multiple output (DDMA-MIMO) radar enables the design of orthogonal waveform in Doppler domain instead of in time domain. Thus DDMA-MIMO radar performs well in long range radar application. However, it suffers from Doppler ambiguous and energy defocus of the target spectrum in DDMA-MIMO radar, and as a result the target detection performance degrades. To tackle these problems, a target detection algorithm based on multiple subbands coherent-accumulation (MSCA) is proposed in this paper. First, the empty-band is inserted into the Doppler domain by modifying the phase modulation of the transmitting antennas. Based on the periodic extension of Doppler in DDMA-MIMO system, a coherent accumulation and Doppler ambiguity mitigation method based on subband correlation is proposed. By exploiting the low energy characteristic of the empty subband, this method compares the energy of accumulated subband after MSCA to extract the real velocity of target. It also solves the problem of Doppler ambiguity caused by the period extension of target velocity. Besides, the proposed method can improve the detection performance, avoiding the target being drowned by noise. Simulation and real data results show that the proposed method can effectively alleviate the Doppler ambiguity, improve the target detection performance under low signal-to-noise scenarios.