Uma técnica para redução de interferência de múltiplo acesso em sistemas MC-CDMA

Abstract

Most of the techniques for Multiple Access Interference (MAI) reduction or cancellation in Code-Division Multiple Access systems are applicable only to the up-link. In this case, the radio-base system knows the signature of all users and can apply a Multi-User Detection (MUD) strategy. A new technique is proposed in this work to reduce the influence of MAI on the down-link of a Multi-Carrier CDMA (MC-CDMA) system, without resorting to MUD. The technique is based on the use of a pair of spreading sequences especially chosen for each user. These sequences must have special characteristics to reduce the MAI effects on fixed and time varying multi-path Rayleigh fading channels. The proposed technique shows better results in terms of bit error rate if compared with the originally described by H. Zare and D. Liu.