Conflict-Free Vectorized In-order In-place Radix-r Belief Propagation Polar Code Decoder Algorithm

A vectorized belief propagation polar code decoder is desirable because of the potentially high throughput and the ability of integration in processors that perform vectorized processing and access wide memory words. However, current state-of-the-art belief propagation polar code decoder algorithms do not perform vector processing and store intermediate results in non consecutive memory locations. Also the current state-of-the-art belief propagation polar code decoders require separate memories to store left and right bound intermediate results.

In this paper we propose a vectorized in-order in-place belief propagation polar code decoder algorithm where all stages access vectorized data from memory. This results in a high throughput because vectors of elements can be fetched from and stored in memory in each clock cycle. Our algorithm also accommodates for per stage in-place computations which halves the required internal memory. Furthermore, the algorithm has a regular memory addresses access pattern. Conflict free vectorized memory access is achieved by making use of transpose operations on small groups of intermediate results. The use of the transpose operations also results in that both input and output results are placed on subsequent locations in memory.