利用似然比门限转换的自适应机会协作策略

Dynamic opportunistic cooperative strategy with log likelihood ratio switching threshold

基于解码前传的错误传播严重影响机会协作系统的选择分集增益。针对此问题,提出一种基于似然比门限转换的自适应机会协作策略:最优中继采用似然比对接收信号质量进行指示,通过与基于链路误比特率的门限值比较,动态地选择中继方式,以保证中继链路得到充分利用。推导了平均误比特率的近似解析表达式,在此基础上对门限进行了优化。采用蒙特卡罗仿真验证了理论公式的有效性,仿真结果表明,当误比特率为0.001时,相比传统方案,该算法能节省1.2 dB的功率。

Error propagation seriously degenerates the selection diversity of decode-and-forward-based opportunistic cooperative system. Addressing this problem, a Log Likelihood Ratio （LLR） -based adaptive switching scheme was proposed, which aimed at exploiting relay channel more efficiently through dynamic cooperation selection according to the LLR comparison with Bit Error Ratio （BER） -based threshold at relay. Moreover, the closed-form expression of the average BER was derived, and the threshold was optimized accordingly. Monte-Carlo simulations validate the analysis, and the results show that the proposed algorithm achieves 1.2 dB power gain at BER of 0.001, compared to the conventional scheme.