Differential LDPC Coded Cooperative Communication Systems for Internet of Things

Abstract

In this paper, we study an differential LDPC coded cooperative communication systems for improving the communication quality and energy efficiency of the Internet of Things (IoT). In order to avoid the complex channel state information (CSI) estimation, a diffierential LDPC coded cooperative scheme based on multiple-symbol differential detection (MSDD) is first proposed. As the prohibitively high complexity of the decision metric of MSDD soft-input soft-output demodulator (SISOD), a soft-output M-algorithm (SOMA) for reducing the computational complexity of MSDD SISOD is then proposed based on analyzing the conventional M-algorithm that does not work well for MSDD SISOD. To further make the proposed scheme suit for the engineering applications of the IoT, a new method to construct parity check matrix of quasi-cyclic (QC) LDPC codes based on shortening RS codes is proposed for constructing LDPC codes with good minimum distances. The simulation results show that the performance of the systems under consideration can be effectively improved by the proposed scheme with good energy efficiency for the IoT.