مقاله انگلیسی رایگان در مورد مدولاسیون کدگذاری جاگذاری بیتی با کدگشایی تکراری – IEEE 2018

Arikan in his paper [1], proposed a new channel coding scheme by “polarizing” channels w.r.t. their capacities. The process of channel polarization helps to classify every bit channel w.r.t. channel capacity which is used to create a scheme of encoding information bits into a codeword. This form of classification provides a new family of linear block codes called Polar Codes. BICM-ID is a state-of-the-art error correcting scheme. The coded-modulation scheme was proposed in [2] for improving error correction capabilities by using channel coding and modulation schemes as a combined unit instead of independent modules. Adding diversity to the codes by interleaving, should improve the error correction performance as proposed in [3], to hence provide the Bit Interleaved Coded Modulation (BICM) design described in [4]. BICM’s demerits can be overcome by exchanging extrinsic information between multiple modules of the Iterative Decoding (ID) chain iteratively, to improve error correcting capability over every iteration [5]. Such a BICM-ID scheme is helpful for error correction of codes received over AWGN and Fading channels. The idea is to encode the input data bits into codewords generated by polar encoding, interleaving and then modulating them at the transmitter end. Similarly, at the receiver end polar decoder, demodulator, interleaver and de-interleaver iteratively perform their tasks and exchange extrinsic information to produce codeword estimates. The aim in this paper is to develop such a novel BIPCM-ID system and analyze its error correcting capability. Although Arikan’s original idea of channel polarization is limited only to Binary Erasure Channels (BEC) the BIPCM-ID needs to be analyzed over AWGN channels. Thus, a modified approach of channel polarization for AWGN channels is used. The polar decoder which is to be integrated in an ID chain should be a Soft-Input Soft-Output (SISO) decoder so that it can produce extrinsic information to be exchanged with, as well as process the inputs from, the other modules in the ID chain. Modifications can also be made to remove the error floor altogether. These issues have been addressed in this paper. The rest of the paper is organized as follows. In Section II, an overview of Polar Codes and BICM-ID is provided for the reader to get a basic understanding of these concepts. Section III describes the novel approach of integrating Polar Codes in a BICM-ID design by generating the extrinsic information from the decoder module to be used for ID and how the channels are polarized for a AWGN channel. Section IV, provides the simulation results of the BIPCM-ID system, with detailed discussions about the parameters used and the corresponding performance results obtained. Section V provides the key points which merit further research and the existing limitations which can be improved upon. The concluding remarks are mentioned in Section VI. Notations: Letters in bold fonts denote vectors. X and Y denote the Random Variables (RV) corresponding to the input and output of a channel respectively. W denotes a channel as well as the Probability Density Functions (PDF) of the RVs across the channel. N denotes the length of a codeword. Z denotes the Bhattacharyya parameter. L denotes the LogLikelihood Ratio (LLR) values.