Construction of time-frequency codes based on protograph LDPC codes in OFDM communication systems  

作　　者：Kaiyao Wang Yang Xiao Kiseon Kim 

机构地区：[1]Institute of Information Science,Beijing Jiaotong University,Beijing 100044,R R.China [2]Department of Inform ation and Comm unications,Gwangju Institute of Science and Technology,Gwangju 500-712,Korea

出　　处：《Journal of Systems Engineering and Electronics》2012年第3期335-341,共7页系统工程与电子技术（英文版）

基　　金：supported by the Beijing Natural Science Foundation of China (4102050);the National Natural Science of Foundation of China (NSFC)-Korea Science and Engineering Foundation (KOSF) Joint Research Project of China and Korea (60811140343)

摘　　要：This paper proposes a scheme to construct time- frequency codes based on protograph low density parity check （LDPC） codes in orthogonal frequency division multiplexing （OFDM） communication systems. This approach synthesizes two techniques： protograph LDPC codes and OFDM. One symbol of encoded information by protograph LDPC codes corresponds to one sub-carrier, namely the length of encoded information equals to the number of sub-carriers. The design of good protograph LDPC codes with short lengths is given, and the proposed proto- graph LDPC codes can be of fast encoding, which can reduce the encoding complexity and simplify encoder hardware implementa- tion. The proposed approach provides a higher coding gain in the Rayleigh fading channel. The simulation results in the Rayleigh fading channel show that the bit error rate （BER） performance of the proposed time-frequency codes is as good as random LDPC- OFDM codes and is better than Tanner LDPC-OFDM codes under the condition of different fading coefficients.This paper proposes a scheme to construct time- frequency codes based on protograph low density parity check （LDPC） codes in orthogonal frequency division multiplexing （OFDM） communication systems. This approach synthesizes two techniques： protograph LDPC codes and OFDM. One symbol of encoded information by protograph LDPC codes corresponds to one sub-carrier, namely the length of encoded information equals to the number of sub-carriers. The design of good protograph LDPC codes with short lengths is given, and the proposed proto- graph LDPC codes can be of fast encoding, which can reduce the encoding complexity and simplify encoder hardware implementa- tion. The proposed approach provides a higher coding gain in the Rayleigh fading channel. The simulation results in the Rayleigh fading channel show that the bit error rate （BER） performance of the proposed time-frequency codes is as good as random LDPC- OFDM codes and is better than Tanner LDPC-OFDM codes under the condition of different fading coefficients.

关 键 词：time-frequency code protograph low density parity check （LDPC） code orthogonal frequency division multiplexing （OFDM） fast encoding algorithm. 

分 类 号：TN911.22[电子电信—通信与信息系统] V243[电子电信—信息与通信工程]