Interference Cancelling Codes for Ultra-Reliable Random Access

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2018-12
Major/Subject
Mcode
Degree programme
Language
en
Pages
12
Series
International Journal of Wireless Information Networks
Abstract
Combinatorial code designs (CCDs) are proposed as a means for achieving ultra-reliability in the random access channel. In contrast to traditional access protocols that use random repetition coding, we show that by uniquely allocating repetition patterns to users, successful reception may be guaranteed up to a number of simultaneously active users in small frame sizes. Such codes are particularly robust in the low activity region where mission-critical machine-type communication is expected to operate. We also present deterministic codes designed to work in conjunction with successive interference cancellation to further improve reliability. The optimal IC code for frames of 5 access slots is given. Unlike slotted ALOHA, it is shown to limit packet losses to well below the ultra-reliability threshold (10−5). These error performance gains come at the cost of a strict limitation on the supported user population (11 users in the case of 5 slots). We therefore consider larger frames of 24 slots, and analyse heuristic, low-complexity CCDs with fixed repetition factors that support up to 2024 users. While these are sub-optimal IC codes, significant gains are still observed compared to random codes.
Description
Keywords
Collision resolution, Interference cancelling codes, Random access, Successive interference cancellation, Ultra-reliability
Other note
Citation
Boyd , C , Vehkalahti , R & Tirkkonen , O 2018 , ' Interference Cancelling Codes for Ultra-Reliable Random Access ' , International Journal of Wireless Information Networks , vol. 25 , no. 4 , pp. 422–433 . https://doi.org/10.1007/s10776-018-0411-6