MAI mitigation by SIC for a multicarrier CDMA system

Abstract

Summary form only given. In a code division multiple access (CDMA) system, multiple access interference (MAI) coupled with the near-far problem is one of the major factors limiting system performance. To overcome these issues, various multiuser detection schemes have been proposed. The complexity of the multiuser detection schemes is important, especially when they are adopted in a multicarrier DS/CDMA system which employs lots of subcarriers. Successive interference cancellation (SIC) is relatively simpler than other multiuser detection schemes when used in a multicarrier CDMA system because it does not require separate channel estimation for each of the subcarriers. A SIC scheme based on order statistics is proposed and analyzed for a multicarrier CDMA system over a Rayleigh fading channel. The SIC scheme is employed for each subcarrier, and the subcarrier signals, after interference cancellation, are combined through maximal-ratio or equal-gain combining techniques. The effect of imperfect interference cancellation is also investigated. From the numerical results, it is shown that the proposed system achieves significant performance improvement over a conventional multicarrier CDMA system. The proposed system is robust to MAI and the near-far problem, which translates to a significant increase in system capacity.