Efficient Feasibility Examination for Successive Interference Cancellation in DS-CDMA Systems

On the uplink of a DS-CDMA system, successive interference cancellation (SIC) technique can be employed to reduce multiple access interference and improve system capacity. In such a system with K active users, there are K possible decoding orders of SIC and not every decoding order is feasible due to some constraints. It is highly time-consuming to examine the system feasibility directly by using the exhaustive search method (ESM) for a system with even a moderate number of users. In this paper, we propose an efficient approach for examining the feasibility of DS-CDMA systems with imperfect SIC. The proposed approach has significantly less computational complexity than that of ESM, thus benefits the quick decision of admission control and/or scheduling in DS-CDMA systems. Furthermore, under the decoding order obtained by the proposed approach, we prove that the system is able to achieve the lowest outage probability among all possible decoding orders. Simulation experiments and numerical results validate our analysis and demonstrate the effectiveness of our approach.