Performances of LDPC based multi-user space time diversity system design for uplink multi-carrier CDMA

We examine the performance of a multiuser space time diversity system for an uplink environment when it is interfaced by an LDPC code. The proposed structure uses a new combination of STBC, OFDM and CDMA spreading. The OFDM codewords are built from chips issued from different symbols. The STBC encoding is done at the last stage of the transmitter and we place the STBC decoder after multiuser mitigation. We show that our system is particularly easy to implement while obtaining similar performance compared to a single user STBC system. We show furthermore that the performance of the system, when concatenated with an LDPC code, can be increased when an additional large symbol interleaver is used.