Air-interface techniques for achieving high data rates for UMTS

Chip-level simulation results of QPSK, 8PSK, 16QAM and 64QAM modulation schemes with either rate- 1/2 or rate-3/4 turbo codes (TCs) in wideband code division multiple access (WCDMA) downlink over various narrowband and wideband channels are presented. Post-decoding bit error rate (BER) is used as a performance measure. Implementation issues and achieved performance are discussed, particularly when space time transmit diversity (STTD) is employed. It is indicated that the STTD significantly improves the link performance in narrowband channels. In a wideband channel, however, the simple STTD processing enhances only the MPSK modulated link. A more elaborate STTD processing is required to improve the MQAM modulated link.