Year: 2019
Type: dissertation
Abstract: Ultra reliable low latency communication (URLLC) is an important feature in \nfuture mobile communication systems, as they will require high data rates, large \nsystem capacity and massive device connectivity [11]. To meet such stringent \nrequirements, many error-correction codes (ECC)s are being investigated; turbo \ncodes, low density parity check (LDPC) codes, polar codes and convolutional codes \n[70, 92, 38], among many others. In this work, we present generalized low density \nparity check (GLDPC) codes as a promising candidate for URLLC. \nOur proposal is based on a novel class of GLDPC code ensembles, for which \nnew analysis tools are proposed. We analyze the trade-o_ between coding rate and \nasymptotic performance of a class of GLDPC codes constructed by including a \ncertain fraction of generalized constraint (GC) nodes in the graph. To incorporate \nboth bounded distance (BD) and maximum likelihood (ML) decoding at GC nodes \ninto our analysis without resorting to multi-edge type of degree distribution (DD)s, \nwe propose the probabilistic peeling decoding (P-PD) algorithm, which models the \ndecoding step at every GC node as an instance of a Bernoulli random variable with \na successful decoding probability that depends on both the GC block code as well \nas its decoding algorithm. The P-PD asymptotic performance over the BEC can \nbe efficiently predicted using standard techniques for LDPC codes such as Density \nevolution (DE) or the differential equation method. We demonstrate that the \nsimulated P-PD performance accurately predicts the actual performance of the \nGLPDC code under ML decoding at GC nodes. We illustrate our analysis for \nGLDPC code ensembles with regular and irregular DDs. \nThis design methodology is applied to construct practical codes for URLLC. \nTo this end, we incorporate to our analysis the use of quasi-cyclic (QC) structures, \nto mitigate the code error floor and facilitate the code very large scale integration \n(VLSI) implementation. Furthermore, for the additive white Gaussian noise \n(AWGN) channel, we analyze the complexity and performance of the message \npassing decoder with various update rules (including standard full-precision sum product and min-sum algorithms) and quantization schemes. The block error rate \n(BLER) performance of the proposed GLDPC codes, combined with a complementary \nouter code, is shown to outperform a variety of state-of-the-art codes, for \nURLLC, including LDPC codes, polar codes, turbo codes and convolutional codes, \nat similar complexity rates.
Author: Liu, Yanfang
Language: English
Subfield: Computer Networks and Communications
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6981956389