MMSE frequency combining for CI/DS-CDMA

In carrier interferometry (CI) DS-CDMA, novel chip shaping is used to introduce frequency diversity benefits to DS-CDMA systems. These frequency diversity benefits result in significant performance enhancements relative to the traditional DS-CDMA. In the CI/DS-CDMA receiver, two stages of combining are present: frequency combining to recreate chips, and chip combining to eliminate interfering users on the system. In the frequency combining, the combiner recreates chips while (1) minimizing interference and (2) creating optimal frequency diversity gain. The authors propose a novel MMSE frequency combiner for the CI/DS-CDMA receivers which achieves enhanced frequency combining. The performance results demonstrate that for P(ε)=10^-3, a 5 dB performance improvement is achieved through use of the novel frequency combiner in CI/DS-CDMA receivers