Column-Pair Scrambled Chip-Interleaved DS-CDMA for Asynchronous Uplink

This paper describes a new scrambling method that reduces multi-path interference (MPI), without compromising the multi-user interference (MUI)-free properties. The column-pair scrambling (CPS) method is suitable for iterative data transmission schemes, such as chip-interleaved block spread (CIBS) - code division multiple access (CDMA) or interleaved frequency domain multiple access (IFDMA). The proposed CPS improves its bit error rate (BER) performance, without requiring unrealizable synchronization of transmission-timing control amongst all users. This improvement depends on the number of active users, and the worst BER performance of the CPS is the same as fully loaded conventional CIBS-CDMA or IFDMA systems. The simulation results also show that the proposed CPS improves BER performance under fading channels