Increasing User Capacity for CDMA Systems by Using Multi-Modes Turbo En-Decoding

摘要

With the number of mobile users rapidly increasing, the capacity of CDMA systems becomes a pressure. Classical Turbo en-decoding is only used to channel en-decoding for CDMA systems, in this paper we present multi-modes Turbo en-decoding to increasing the capacity of the CDMA systems. The scheme is based on the code division multiple access scheme and Turbo en-decoding filtering presented by us. In a CDMA cell, base station adopts K Turbo en-decoders to divide the mobile users in the cell into K different groups. The N spreading codes of a cell can be assigned to different mobile stations in the K different Turbo en-decoding groups, so the number of users in a CDMA cell can be increased K times. The bank of matched filters is used to detect user signals in the same Turbo group, so the number of users can be K times of original one. Simulations verified the approach to be effective.