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Construction of Rate-Compatible Punctured Polar Codes Using Hierarchical Puncturing

In this paper, we present an efficient method to construct a rate-compatible punctured polar (RCPP) code. In the proposed method, a common information set is simply optimized for the highest rate and then, it is effectively improved for the other codes in the family, by satisfying the condition that information bits are kept during retransmissions. This is enabled by proposing a novel hierarchical puncturing and information-copy technique. Specifically, some information bits (carefully chosen according to puncturing patterns) are copied to frozen-bit channels, yielding an information-dependent frozen vector. The improved information sets are then obtained by properly combining the common information set and the information-dependent frozen vector. Furthermore, the impact of “unknown” frozen bits are cleverly addressed using the property of the proposed hierarchical puncturing. Simulation results are provided to verify the superiority of the proposed construction method.