基于低密度奇偶校验编码的自适应调制方案

Adaptive modulation scheme based on low-density parity-check coding

为克服无线信道时变衰落特性对传输性能的影响 ,提出了基于低密度奇偶校验 (L DPC)编码的自适应调制传输方案。该方案将所有子信道传输的信息采用同一个 L DPC码进行编码 ,每个子信道根据各自当前的噪声水平动态选取调制方式 ,而各个子信道的瞬时噪声根据 L DPC译码前后信息序列的符号改变情况进行估计。仿真结果表明 :在 Nakaga-mi时变衰落信道下 ,该系统方案可以很好地适应信道的时变衰落特性 ,在满足系统输出误比特率的条件下 ,可以很低的系统复杂度实现信息的最佳传输 ,并获得距离理论极限3d

An adaptive modulation scheme was developed based on low-density parity-check (LDPC) coding to eliminate the transmission performance degradation caused by time-variant fading interference in wireless channels. The scheme employed an LDPC code to encode all subchannel transmitted bits, with every subchannel dynamically selecting its modulation scheme according to its instantaneous channel bit-error-rate estimated from the bit sequences before and after the LDPC decoding. Simulation results show that, over Nakagami-fading channels, the proposed transmission scheme is well adapted to time-variant wireless channels, achieving an optimal information transmission rate with very low system complexity, with substantial improvements in the bit-error-rate. Specifically, the scheme achieved a transmission rate within 3 dB of the theoretical limit.