Quantum Multi-user Detection Scheme with Discrete Coherent States Approximation

Multi-user detection (MUD) techniques will be adopted in the future wired and wireless communication system. It is known that quantum detection techniques promise efficient optimal solutions to this NP (non-polynomial) hard problem in classical domain. "Discrete coherent state"(DCS) approximation method is a practical model for solving the mixed-state detection problem. In this paper, we use DCS approximation model for the MUD problem. For a noisy quantum channel, it is feasible to consider the output states are mixed states, which are the input pure states corrupted by the noise when the pure states pass thought the noisy quantum channel. For simplicity and generality, we deduce the error probability of symbol against correlation coefficient in two users' fashion. By numerical simulations, we analyze and compare the performance of this representation. The simulation results show that the detection error will increase while the correlation coefficient increase, and the performance is also effected by the noise level. With less noise, the system will get better performance. The DCS approximation representation is a good detection scheme for quantum multi-user detection.