Abstract: Polar codes are important channel coding for the fifth generation mobile communication (5G), which are already used for control channels for enhance mobile broadband (eMBB) scenarios. At present, the 5G-polar codes specified in the 3GPP TS 38.212 standard have three code structures, but the design reasons and corresponding decoding methods have not been given yet. Firstly, the reliability sequence design and rate-matching method are introduced, and then the principle, the key feature and the decoding algorithm of every code structure are analyzed. Through the performance and complexity comparison analysis of three kinds of polar codes, the applicable condition and reason for each code structure are detailed. At the same time, the performance advantages of the short-size 5G-polar codes over LTE TBCC and 5G-LDPC codes are given quantitatively by computer simulations.

Key words: polar codes, enhance mobile broadband, rate-matching, distributed cyclic redundancy check