Polar codes, first achieving the capacity of symmetric binary-input discrete memoryless channels (B-DMCs), have been standardized for eMBB control channels. Since 5G cellular requires flexible architecture which is realized by the software defined networking paradigm, efficient polar decoder is anticipated. Though successive cancellation list (SCL) decoder achieves satisfactory performance, it requires a large amount of memory. For short control channel codes, sphere decoder (SD) is an alternative, but costs unbearable time complexity at low signal-to-noise ratio. List sphere decoder (LSD) abandons the radius and keeps a list of best paths to gain a fixed complexity. However, LSD needs a large list size L for satisfactory performance. In this paper, an efficient software LSD with path pruning and efficient sorting is proposed. We recall the radius as the bound to delete the paths out of the sphere at very early levels. Since L is dynamic, efficient sorting is proposed to reduce the copy operations. Implemented with C++, the proposed decoder can reduce up to 65.3% latency compared with the original LSD, with the same performance and lower complexity.

极性代码首先实现了对称二进制输入离散无记忆通道（B-DMC）的容量，现已针对eMBB控制通道进行了标准化。由于5G蜂窝网络需要通过软件定义的联网范例来实现的灵活架构，因此有望实现高效的极性解码器。尽管连续消除列表（SCL）解码器获得了令人满意的性能，但它需要大量的内存。对于短控制信道代码，可以使用球面解码器（SD），但在低信噪比的情况下，它会花费难以忍受的时间复杂度。列表球解码器（LSD）放弃半径，并保留最佳路径列表以获取固定的复杂度。但是，LSD需要较大的列表大小L以获得令人满意的性能。本文提出了一种具有路径修剪和有效排序功能的高效软件LSD。我们记得半径是在很早的水平就将路径从球体中删除的范围。由于L是动态的，因此提出了有效的排序以减少复制操作。与原始LSD相比，采用C ++实现的拟议解码器可将延迟降低多达65.3 ％，并且性能相同且复杂度较低。