Polar code is the first error control code achieving the channel capacity and has been accepted as the coding scheme of the control channels of the 5G wireless communication systems, which is the great breakthrough of the channel coding field in recent years. In this paper, the primary principle of the polar code and the application in 5G systems are surveyed. First, based on the viewpoint of channel polarization, the butter-fly structure of polar coding and successive cancellation decoding are analyzed. Then, the concatenated polar code is proposed and the characteristics of high-performance decoding algorithms are summarized. Furthermore, the design of polar codes in 5G systems is addressed and three practical coding schemes of polar codes are overviewed, which is puncturing, shortening and repetition. In the end, it is pointed out that polar coded information processing will become the new diagram of the communication system optimization in the future.
polar code; channel polarization; successive cancellation decoding; successive cancellation list decoding; successive cancellation stack decoding; polar coded information processing