重叠编码放大转发协作通信系统研究

Research on the amplify-and-forward cooperative communication systems combining with overlapped code division multiplexing

为进一步提升协作通信系统的频谱效率，将重叠编码复用技术引入协作通信，设计了采用重叠编码的放大转发（ampli-fy-and-forward，AF）系统，并采用复数域的Viterbi解码算法对其进行译码。在平坦Rayleigh衰落信道下的仿真表明，通过改变不同的编码复用系数，新系统仅使用二阶调制就能使频谱效率高于1（b/s）/Hz。此外，在相同频谱效率下，较传统高阶调制AF协作通信系统，新系统的误比特率（bit error rate，BER）性能有显著提升，如当BER等于10-3时，新系统的每比特能量与噪声功率谱密度之比（Eb/N0）将减少6～7 dB。

Overlapped code division multiplexing （OVCDM）is applied in the cooperative communication system to improve the spectrum efficiency.A scheme combining amplify-and-forward （AF）cooperative communication system with OVCDM is pro-posed,and Viterbi algorithm in complex domain is used to decode it.The simulation under the flat fading Rayleigh channel shows that the spectrum efficiency of the proposed system is higher than 1 （b/s）/Hz only using binary modulation by changing different coding multiplexing coefficients.Furthermore,under the same spectrum efficiency,the bit error rate （BER）performance is im-proved significiantly compared with the high order modulation AF cooperative communication system.The energy per bit to noise power spectral density ratio （Eb/N0 ）of the proposed system will decreases 6-7 dB when BER equals to 10-3 .