Adaptive Wireless Transceivers: Turbo-Coded, Turbo-Equalised and Space-Time Coded TDMA, CDMA, MC-CDMA and Ofdm Systems
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This paper discusses the application of adaptive modulation and adaptive rate turbo coding to orthogonal frequency-divisions multiplexing (OFDM), to increase throughput on the time and frequency selective channel. The adaptive turbo code scheme is based on a subband adaptive method, and compares two adaptive systems: a conventional approach where a separate turbo code is used for each subband, and a single turbo code adaptive system which uses a single turbo code over all subbands. Five modulation schemes (BPSK, QPSK, 8AMPM, 16QAM, and 64QAM) are employed and turbo code rates considered are 1/2 and 1/3. The performances of both systems with high (10-2) and low (10-4) BER targets are compared. Simulation results for throughput and BER show that the single turbo code adaptive system provides a significant improvement.