A capacity-complexity trade-off for CDMA with multi-user demodulation

Multi-user demodulation and decoding (MUD) can offer significant improvements in performance of CDMA systems, but their limited practical use is due to the large computational complexity. In this paper, we perform the capacity evaluation for MUD with non-uniform chip-level signaling and observe that MUD complexity can be greatly reduced by trading-off some proportion of the full MUD channel capacity. This trade-off between the MUD channel capacity and the MUD complexity can be used to improve performance of CDMA systems. Consequently, we present simulation results illustrating that by selecting appropriate non-uniform chip probabilities, our considered CDMA system can achieve a good throughput and great reduction in multi-user interference and MUD implementation complexity.