{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:44:06Z","timestamp":1760240646168,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2019,8,15]],"date-time":"2019-08-15T00:00:00Z","timestamp":1565827200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Algorithms"],"abstract":"<jats:p>This work addresses the physical layer channel code design for an uncoordinated, frame- and slot-asynchronous random access protocol. Starting from the observation that collisions between two users yield very specific interference patterns, we define a surrogate channel model and propose different protograph low-density parity-check code designs. The proposed codes are both tested in a setup where the physical layer is abstracted, as well as on a more realistic channel model, where finite-length physical layer simulations of the entire asynchronous random access scheme, including decoding, are carried out. We find that the abstracted physical layer model overestimates the performance when short blocks are considered. Additionally, the optimized codes show gains in supported channel traffic, a measure of the number of terminals that can be concurrently accommodated on the channel, of around 17% at a packet loss rate of     10  \u2212 2      w.r.t. off-the-shelf codes.<\/jats:p>","DOI":"10.3390\/a12080170","type":"journal-article","created":{"date-parts":[[2019,8,15]],"date-time":"2019-08-15T11:11:00Z","timestamp":1565867460000},"page":"170","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Protograph LDPC Code Design for Asynchronous Random Access"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9688-2436","authenticated-orcid":false,"given":"Federico","family":"Clazzer","sequence":"first","affiliation":[{"name":"Institute of Communications and Navigation of the German Aerospace Center (DLR), D-82234 Wessling, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0133-6564","authenticated-orcid":false,"given":"Bal\u00e1zs","family":"Matuz","sequence":"additional","affiliation":[{"name":"Institute of Communications and Navigation of the German Aerospace Center (DLR), D-82234 Wessling, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sachini","family":"Jayasooriya","sequence":"additional","affiliation":[{"name":"School of Electrical Engineering and Computing, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2742-5140","authenticated-orcid":false,"given":"Mahyar","family":"Shirvanimoghaddam","sequence":"additional","affiliation":[{"name":"Center for IoT and Telecommunications, School of Electrical and Information Engineering, The University of Sydney, Darlington, NSW 2006, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sarah J.","family":"Johnson","sequence":"additional","affiliation":[{"name":"School of Electrical Engineering and Computing, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,8,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1109\/MCOM.2014.6815890","article-title":"Scenario for 5G mobile and wireless communications: The vision of the METIS project","volume":"52","author":"Osseiran","year":"2014","journal-title":"IEEE Commun. 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