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首先介绍了OFDM系统中的自适应调制技术,然后在chow自适应调制算法的基础上提出一种改进的OFDM自适应比特分配算法,该算法适用于严重频率选择性衰落、信噪比较低的情况.仿真结果表明,在相同频带利用率情况下,使用自适应调制技术的OFDM系统与传统的使用固定比特分配的OFDM系统相比,误比特性能有了显著提高;改进的自适应调制算法性能与原算法相近,但实现简单、性能稳定,适合在宽带无线通信系统中运用.
Firstly, the adaptive modulation technique in OFDM system is introduced. Then an improved OFDM adaptive bit allocation algorithm is proposed based on chow adaptive modulation algorithm. This algorithm is suitable for severe frequency selective fading with low SNR The simulation results show that the OFDM system using adaptive modulation technology has significantly improved bit error performance compared with the conventional OFDM system using fixed bit allocation under the same frequency band utilization. The performance of the improved adaptive modulation algorithm Similar to the original algorithm, but simple to achieve, stable performance, suitable for use in broadband wireless communication systems.