Concatenated Polar Codes

Polar codes have attracted much recent attention as the first codes with low computational complexity that provably achieve optimal rate-regions for a large class of information-theoretic problems. One significant drawback, however, is that for current constructions the probability of error decays sub-exponentially in the block-length (more detailed designs improve the probability of error at the cost of significantly increased computational complexity). In this paper, the authors show how the classical idea of code concatenation - using "Short" polar codes as inner codes and a "High-rate" Reed-Solomon code as the outer code - results in substantially improved performance.