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将自适应调制技术和空间分集技术有机地结合起来 ,提出了一种与简单空时编码发射机分集相结合的恒定比特率自适应正交频分复用 (OFDM)方案。该算法根据两径发射机的平均信噪比在各子载波上自适应地选择不同的调制模式 ,并保持恒定比特率。仿真结果表明 :在多径瑞利衰落信道下 ,该方案可以显著地改善 OFDM的性能。在无信道编码和误比特率为 10 - 5条件下 ,对于平均带宽效率为1bit/ (s.Hz)的双天线发射分集接收的自适应 OFDM系统与传统 OFDM系统相比可以获得约 35 d B的自适应分集增益。
Combining adaptive modulation technology and space diversity technology, a constant bit rate adaptive orthogonal frequency division multiplexing (OFDM) scheme is proposed, which is combined with simple space-time coded transmitter diversity. The algorithm adaptively selects different modulation modes on each subcarrier according to the average signal-to-noise ratio of the two-path transmitter and maintains a constant bit rate. The simulation results show that this scheme can significantly improve the performance of OFDM under the multipath Rayleigh fading channel. The adaptive OFDM system with dual-antenna transmit diversity reception with average bandwidth efficiency of 1 bit / (s.Hz) achieves approximately 35 dB compared to the conventional OFDM system, with no channel coding and bit error rate of 10 - 5 Adaptive diversity gain.