LTE中PDCCH有效控制信道元素的软判决检测算法

在LTE系统的PDCCH盲检中，检测信道中的有效控制信道元素（CCE）是一种常用的盲检加速方法。对于有效CCE的检测，基于硬判决的能量检测与融合判决相结合的方法是一种常用手段，但随着信道环境的下降这种方法的可靠性也会大幅降低。为了确保低较差信道条件下的可靠性和提高算法性能，本文提出了一种基于软判决的有效CCE检测算法。利用奈曼-皮尔逊准则推导出满足系统可靠性需求的最佳软判决检测阈值，降低错检概率，提高了原有检测方法的性能。本文推导了判决的软信息形式，给出检测的软判决门限。仿真结果证明了理论推导的正确性。与硬判决相比，如系统在SNR = -2dB，漏警率均为0.15时，软判决虚警率降低了82%，表明所提算法可以有效保证检测的低漏警率并降低虚警的发生概率。 

Soft-decision Based PDCCH Valid CCEs Detection in LTE

Among the PDCCH blind detections for the LTE system, a common method used for the acceleration is detecting the valid CCEs in the channel. For the detection of valid CCEs, a common approach is the hard-decision based energy detection combining with fusion rule.However, the reliability of this method will be greatly reduced under low signal-to-noise ratio.To improve the performance, a soft-decision based algorithm for detection of valid CCEs is proposed in this paper. The optimum soft-decision detection threshold satisfying system reliability requirements is deduced by Neyman-Pearson. The probability of false dectection is reduced and the performance of original detection method can be improved by soft-decision. The soft-decision form and threshold for valid CCEs detection are deduced. in this paper. The correctness of the theoretical deduction is proved by simulations. Compared with hard-decision, for instance, the false alarm rate of soft-decision decreases by 82% when the missing alarm rate is 0.15 and SNR = -2dB. The results indicate that the proposed algorithm effectively reduce the missing alarm probability and false alarm probability.