- Title
- Protograph LDPC code design for asynchronous random access
- Creator
- Clazzer, Federico; Matuz, Balázs; Jayasooriya, Sachini; Shirvanimoghaddam, Mahyar; Johnson, Sarah J.
- Relation
- Algorithms Vol. 12, Issue 8, no. 170
- Publisher Link
- http://dx.doi.org/10.3390/a12080170
- Publisher
- MDPI AG
- Resource Type
- journal article
- Date
- 2019
- Description
- 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 10−2 w.r.t. off-the-shelf codes.
- Subject
- medium access control; grant-free access; unequal error protection; successive interference cancellation; physical layer simulations; quantized density evolution; Gaussian interference channel
- Identifier
- http://hdl.handle.net/1959.13/1456349
- Identifier
- uon:45213
- Identifier
- ISSN:1999-4893
- Rights
- © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
- Language
- eng
- Full Text
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