Adaptive Modulation Techniques In OFDM Systems

OFDM has been regarded as the key technology for future broadband wireless communication systems, due to its robust to multipath-fading and high frequency efficiency. Adaptive modulation technique in OFDM systems can improve system performance significantly by adaptively assigning appropriate modulation modes and signal power to different subchannels. Research on adaptive modulation techniques in OFDM systems will be much valuable for the development of future broadband wireless communication systems. Adaptive bit- and power-loading algorithms are fundamental elements of adaptive modulation techniques in OFDM systems. Thus, the main tasks in this thesis are to develop basic theoretics about adaptive bit- and power-loading algorithms, and design new efficient loading algorithms for OFDM systems.Basing on the in-depth study of adaptive modulation theoretics and conventional loading algorithms, some fruitful theoretical researches and algorithms design work have been carried out with regard to the problems of loading algorithms and the practical requirements by future systems. This thesis presents some new theorems which are instructive for the designs of other loading algorithms, and some new efficient loading algorithms which are more applicable for practical implementations.The main tasks and contributions in this thesis can be summarized as followsFirstly, this thesis proposes an optimal power distribution theorem...