A differential QAM detection in uplink massive MIMO systems

In this paper, we address differential non-coherence detections in uplink massive multiple input multiple output (MIMO) systems. Utilizing the channel statistics information, a special 16 quadrature amplitude modulation (QAM) can be adopted to achieve differential detection in uplink massive MIMO systems, which avoids costs of pilots or channel estimation. In addition, a higher-order extension of this differential 16-QAM is also presented in this paper. Moreover, it is found that users in different cells can transmit symbols simultaneously without causing interference to each other by jointly processing signals from all base stations if the number of receive antennas goes to infinity. For comparison, we also provide the performances of the differential amplitude phase shift keying (DAPSK) and coherence detection with pilot contamination in uplink massive MIMO systems, respectively. Simulation results show that the proposed differential 16-QAM scheme exhibits significant advantage over 16-DAPSK, and exhibits a large performance gain compared with the coherence detection with pilot contamination.