Research On Several Key Technologies Of Polar Code

Polar code is a new channel coding scheme first proposed by E. Arikan in 2009. This coding scheme based on channel polarization to design codeword, is currently the only proved channel coding scheme which can achieve the Shannon capacity. Meanwhile, Polar code has low encoding and decoding complexity, especially the low error rate performance in large data transmission, which makes it particularly suitable for communication system with high data transmission requirements, like the future 5G communication system.As the Shannon limit can be achieved with Polar code length tending into infinite, while for the real communication system, Polar code length is limited. Thus, to what extend a finite-length Polar code can achieve the channel capacity, the effectiveness of Polar decoding algorithm, the information bit channel selection based on channel polarization, and the joint design problems of Polar code with other modules in real communication systems are all still open.In this paper, the construction and decoding algorithms of Polar code and several key technologies in wireless transmission are studied, including information bit channel selection of Polar code, advanced decoding algorithm and the system quantification, Polar code with bit-interleaved coded modulation technology, joint design of Polar code and physical layer network coding, and information transmission rate upper bound of interference network system. Specific researches are on the following five areas:1. On the problem of selecting information bit channel for Polar code properly, this paper proposed bit channel entropy parameter selection method which is suitable for a variety of channel models. This method based on channel detection, so the bit channel entropy parameter can measure the real-time status of the channel more accurate, not only improved the utilization of channel detection module in real communication systems, but also improved the error rate performance of Polar code effectively. Simulation also founds that, bit channel entropy parameter selection method is very robust, and the system performance based on bit channel entropy parameter selection method is better than that of Bhattacharyya parameter selection method. In addition, a simple uniform quantization is effective for Polar code in practical communication systems.(2) On the improvement of Polar code decoding algorithm, this paper analyzes the minimum block error rate of SCL decoding algorithm theoretically, and then gives the achieve extent of CA-SCL algorithm to the theoretical minimum block error rate. Simulation founds that a 16-bit CRC checksum code aided SCL algorithm can achieve the minimum block error rate of SCL decoding algorithm.(3) On the joint design of Polar code with bit-interleaved coded modulation technology, this paper presents a serial Polar code bit-interleaved coded modulation scheme, and analyzed the system performance in AWGN and Rayleigh fading channel with different modulations, interleaving algorithms and Polar decoding algorithms. Compared with the serial LDPC code bit-interleaved coded modulation scheme, the BER performance of serial Polar code bit-interleaved coded modulation is better.(4) Based on multi-user relay communication system, this paper proposed a joint designation system of Polar code and physical layer network coding, which saved the hardware equipments and information exchange time in relay node compared with direct network coding scheme. Simulations on system performance of joint relaying strategy in AWGN channel and Rayleigh fading channel founds that, compared to the joint designation system using LDPC codes and convolution codes, the proposed scheme not only obtained a better BER performance, but also gains a lower encoding and decoding algorithm complexity and a smaller system latency.(5) On the information transmission rate of two-user interference network with HK scheme, a method based on the constellation inequality to calculate the information transmission rate upper bound on weak interference region is proposed. The effect of different message sending and receiving procedures between strong and weak interference region are considered in the proposed method. Simulation results show that the proposed method can calculate the information transmission rate upper bound more reasonable.Alrough Polar code can achieve the Shannon limit theoretically, the performance of Polar code will suffer a loss when it is applied in real communication system. Therefore, it is necessary to combine Polar code with a variety of the key technologies in real communication systems to reduce this loss. The researches on the joint designation of Polar code with the above techniques in this paper can provide a reference for the future communication system with Polar code.