OFDM系统中新的编码调制算法研究

传统位交织编码调制（BICM）算法由于受信道准静止性和频率选择特性的制约，应用范围受限。该文将基于固定门限的子带自适应编码调制方法（AMC）和构造在双正交序列集上的比特交织编码调制方案结合，应用于正交频分复用（OFDM）系统中，提出一种AMC-BIC-OFDM级联系统，通过选择子带最低SNR高于门限且吞吐最大的参数作为该子带的调制参数，提高系统频谱利用率，弥补传统BICM由频率选择相关性和信道准静止性带来的编码分集损失，扩展BICM算法的应用。文章在分析系统成对错误概率的基础上，对级联系统的平均信息速率进行了仿真。结果证明，该文级联系统取得高出一般位交织编码调制系统2～6分贝的性能增益。

A Novel Modulation and Coding Technique for OFDM System

The use of traditional bit - interleaved coded modulation is constrained by its sensitive to frequency selective fading and quasi - state feature of channel. This paper proposes the stable threshold based AMC as a method for the dual - orthogonal sequences set bit - interleaved coded OFDM packet transmission in which parameters have the lowest SNR but higher than threshold and have the biggest throughput as sub carrier's modulation parameters, which makes up the coding diversity loss in the result of correlation frequency selective and quasi - state feature of channel in BICM system. System average rate simulation based on pair - wise error probability analyzing is conducted. The results show that the proposed cascade system improves the performance gain by 2 to 6 dB compared to traditional BICM system.