An Improved Solution of Multiuser Detection Based on Quantum Square-Root Measurement

Multi-user detection is becoming one of the key techniques of future wired and wireless communication system. Quantum multi-user detection techniques promise an efficient solution to the NP (non-polynomial) hard problem in the conventional optimal solution of multi-user detection. In this paper, we propose an improved solution of quantum multiuser detection in multi-access quantum channel based on the quantum square-root measurement, by which the minimum square-root probability of error can be gathered. We evaluate the probability of symbol error under various correlation coefficients with PSK modulation, and compare them to that of square-root solution with OOK modulation. The simulation results illustrate that the performance of our method can be improved greatly, but with high computation complexity. Then, we design the threshold algorithm and develop a new quantum square-root measurement formula to reduce the computation complexity. It is shown that these methods can lower the complexity greatly in the numerical computation