Photon Counting Based Iterative Quantum Non-Orthogonal Multiple Access with Spatial Coupling

Non-orthogonal multiple access (NOMA) comprises a prospective technology in the 5th generation (5G) and future wireless communications. In this paper, due to intrinsic nonorthogonal properties of coherent state multi-user communications, a new iterative quantum spatial coupling NOMA (q-SC-NOMA) scheme is proposed. The simulation results confirm that, compared to the recent reported multi-stage displacement based receiver (MDR), the q-SC-NOMA scheme is capable of achieving obviously better performance, saving about 3dB mean signal power in 3-user scenario. Moreover, the q-SC-NOMA scheme can obtain the lower bit error rate (BER) than the non-spatial-coupled quantum NOMA (q-NOMA) approach with reduced computational complexity. In particular, the q-SC-NOMA also offers high robustness against many practical quantum domain imperfections, e.g. mode mismatch and dark counts, etc.