Adaptive Repetition Control Using Terminal Mobility for Uplink Grant-Free URLLC

Shinichi Ozaku, Yukiko Shimbo, Hirofumi Suganuma, Fumiaki Maehara

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)


This paper proposes an adaptive repetition control using terminal mobility to alleviate the packet collision for uplink grant-free (GF) ultra-reliable and low-latency communications (URLLC). In GF, the packet collision among mobile stations (MSs) becomes a serious problem because the grant-issuing procedure conducted in grant-based (GB) transmission is eliminated. Especially in the K-repetitions method, intra-cell interference is increased due to excessive repetitions, resulting in decreased reliability. In the proposed approach, the number of necessary repetitions is determined using fading correlation easily obtained from the terminal speed. This is because the time diversity benefit within repetitions is dependent on the fading correlation. Using the proposed repetition control, the number of repetitions can be reduced especially in the low fading correlation, alleviating the packet collision. The effectiveness of our proposed method is demonstrated in an actual multi-user URLLC scenario by computer simulations.

Original languageEnglish
Title of host publication2020 IEEE 91st Vehicular Technology Conference, VTC Spring 2020 - Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781728152073
Publication statusPublished - 2020 May
Event91st IEEE Vehicular Technology Conference, VTC Spring 2020 - Antwerp, Belgium
Duration: 2020 May 252020 May 28

Publication series

NameIEEE Vehicular Technology Conference
ISSN (Print)1550-2252


Conference91st IEEE Vehicular Technology Conference, VTC Spring 2020


  • K-repetitions
  • Ultra-reliable and low-latency communications (URLLC)
  • grant-free (GF)
  • packet collision
  • terminal mobility
  • time diversity

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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