The Research of Adaptive Modulation Technology in OFDM System

Abstract Orthogonal frequency division multiplexing (OFDM) as a special multi-carrier transmission technology has good resistance to narrow-band interference and selective fading ability. Compared with traditional modulation techniques, adaptive can enhance bandwidth efficiency system capacity. Therefore, applying in OFDM systems take full advantage of spectrum resources, it is suitable for the high-speed reliable mobile communication future. The purpose this paper improve algorithms (Hughes-Hartogs, Chow) realize bits allocation, power allocation better. In paper, simulation results demonstrated that improved Levin-Campello algorithm lowers algorithm’s complexity greatly owns better flexibility, at same time, guarantees bit error rate (BER) performance be applied speech (fixed rate) data (variable wireless systems.