Design and Evaluation of Information Bottleneck LDPC Decoders for Digital Signal Processors

Jan LEWANDOWSKY  Gerhard BAUCH  Matthias TSCHAUNER  Peter OPPERMANN  

Publication
IEICE TRANSACTIONS on Communications   Vol.E102-B   No.8   pp.1363-1370
Publication Date: 2019/08/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2018TTI0001
Type of Manuscript: INVITED PAPER (Special Section on Technology Trials and Proof-of-Concept Activities for 5G and Beyond)
Category: 
Keyword: 
mutual information,  channel decoding,  quantization,  information bottleneck method,  

Full Text: FreePDF(1.3MB)


Summary: 
Receiver implementations with very low quantization resolution will play an important role in 5G, as high precision quantization and signal processing are costly in terms of computational resources and chip area. Therefore, low resolution receivers with quasi optimum performance will be required to meet complexity and latency constraints. The Information Bottleneck method allows for a novel, information centric approach to design such receivers. The method was originally introduced by Naftali Tishby et al. and mostly used in the machine learning field so far. Interestingly, it can also be applied to build surprisingly good digital communication receivers which work fundamentally different than state-of-the-art receivers. Instead of minimizing the quantization error, receiver components with maximum preservation of relevant information for a given bit width can be designed. All signal processing in the resulting receivers is performed using only simple lookup operations. In this paper, we first provide a brief introduction to the design of receiver components with the Information Bottleneck method. We keep referring to decoding of low-density parity-check codes as a practical example. The focus of the paper lies on practical decoder implementations on a digital signal processor which illustrate the potential of the proposed technique. An Information Bottleneck decoder with 4bit message passing decoding is found to outperform 8bit implementations of the well-known min-sum decoder in terms of bit error rate and to perform extremely close to an 8bit belief propagation decoder, while offering considerably higher net decoding throughput than both conventional decoders.