Constant throughput adaptive OFDM employing rate-compatible turbo coded modulation

In this paper, two adaptive orthogonal frequency division multiplexing (OFDM) schemes employing rate-compatible turbo coded modulation with power variable subband-by-subband and symbol-by-symbol are proposed. Our object is to reduce the overall transmit power under target bit-error-rate (BER) for constant throughput OFDM transmissions. Simulation results indicate that our adaptive scheme with power variable over symbols exhibits a more than 5 dB signal-noise-ratio (SNR) gain in contrast to non-adaptive turbo coded modulation, and about 1-2 dB SNR gap from our scheme with power variable over subbands. We also discuss the effect of the amount of subbands on our adaptation performance.