Energy efficient random access for the quasi-static fading MAC

Suhas S. Kowshik, Kirill Andreev, Alexey Frolov, Yury Polyanskiy

    Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

    32 Citations (Scopus)


    We discuss the problem of designing channel access architectures for enabling fast, low-latency, grant-free and uncoordinated uplink for densely packed wireless nodes. Specifically, we extend the concept of random-access code introduced at ISIT'2017 by one of the authors to the practically more relevant case of the AWGN multiple-access channel (MAC) subject to Rayleigh fading, unknown to the decoder. We derive bounds on the fundamental limits of random-access coding and propose an alternating belief-propagation scheme as a candidate practical solution. The latter's performance was found to be surprisingly close to the information-theoretic bounds. It is curious, thus, that while fading significantly increases the minimal required energy-per-bit Eb/N0 (from about 0-2 dB to about 8-11 dB), it appears that it is much easier to attain the optimal performance over the fading channel with a practical scheme by leveraging the inherent randomization introduced by the channel. Finally, we mention that while a number of candidate solutions (MUSA, SCMA, RSMA, etc.) are being discussed for the 5G, the information-theoretic analysis and benchmarking has not been attempted before (in part due to lack of common random-access model). Our work may be seen as a step towards unifying performance comparisons of these methods.

    Original languageEnglish
    Title of host publication2019 IEEE International Symposium on Information Theory, ISIT 2019 - Proceedings
    PublisherInstitute of Electrical and Electronics Engineers Inc.
    Number of pages5
    ISBN (Electronic)9781538692912
    Publication statusPublished - Jul 2019
    Event2019 IEEE International Symposium on Information Theory, ISIT 2019 - Paris, France
    Duration: 7 Jul 201912 Jul 2019

    Publication series

    NameIEEE International Symposium on Information Theory - Proceedings
    ISSN (Print)2157-8095


    Conference2019 IEEE International Symposium on Information Theory, ISIT 2019


    Dive into the research topics of 'Energy efficient random access for the quasi-static fading MAC'. Together they form a unique fingerprint.

    Cite this