Efficient Sphere Polar Decoding via Synchronous Determination

Sphere polar decoding can achieve the maximum likelihood (ML) bound. Existing sphere polar decoding ignores that the Euclidean distance of the frozen bits can be determined at earlier decoding levels. In this article, efficient sphere polar decoding is proposed to reduce the complexity. The set-by-set decoding process via synchronous determination is applied to the sphere polar decoding with fixed lower bounds and its multiple-searches version. Numeric results show the proposed decoding reduces much complexity on the low-rate codes compared with the existing sphere decoding while maintaining the same performance. At high signal-to-noise ratios, the latency of the proposed decoding is comparable with the successive cancellation list decoding.