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1826200667733098496
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| collection |
MIT
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| description |
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.
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| first_indexed |
2024-09-23T11:39:59Z
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Article
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| id |
mit-1721.1/136994
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| institution |
Massachusetts Institute of Technology
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| language |
English
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| last_indexed |
2024-09-23T11:39:59Z
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| publishDate |
2021
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| publisher |
Institute of Electrical and Electronics Engineers (IEEE)
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dspace
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| spelling |
mit-1721.1/1369942022-04-01T17:27:48Z Energy efficient random access for the quasi-static fading MAC 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. 2021-11-01T17:29:01Z 2021-11-01T17:29:01Z 2019-09 2019-07 2021-04-15T14:41:01Z Article http://purl.org/eprint/type/ConferencePaper 978-1-5386-9291-2 2157-8117 https://hdl.handle.net/1721.1/136994 2019. "Energy efficient random access for the quasi-static fading MAC." 2019 IEEE International Symposium on Information Theory (ISIT). en 10.1109/ISIT.2019.8849288 2019 IEEE International Symposium on Information Theory (ISIT) Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Institute of Electrical and Electronics Engineers (IEEE) MIT web domain
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| spellingShingle |
Energy efficient random access for the quasi-static fading MAC
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| title |
Energy efficient random access for the quasi-static fading MAC
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| title_full |
Energy efficient random access for the quasi-static fading MAC
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| title_fullStr |
Energy efficient random access for the quasi-static fading MAC
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| title_full_unstemmed |
Energy efficient random access for the quasi-static fading MAC
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| title_short |
Energy efficient random access for the quasi-static fading MAC
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| title_sort |
energy efficient random access for the quasi static fading mac
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| url |
https://hdl.handle.net/1721.1/136994
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