Adaptive hybrid ARQ (A-HARQ) for ultra-reliable communication in 5G

Emerson Cabrera, Gengfa Fang, Rein Vesilo

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

8 Citations (Scopus)


In this paper, we address the need for motivating applications, such as mission critical industrial control and medical applications, to operate under the Ultra-Reliable Communication (URC) mode in the future 5th Generation (5G) cellular wireless networks, while also under strict Quality of Service (QoS) constraints such as ultra-low latency. Reliability has been shown to improve by using Hybrid Automatic Repeat reQuest (HARQ) for the retransmission (RTX) of erroneous packets during poor channel conditions. However, this can increase the delay to unacceptable levels if more than 1 RTX is required. Thus, an Adaptive HARQ (A-HARQ) scheme is proposed, where RTX are done on better quality sub-bands, with resources dynamically allocated based on Channel Quality Indicator (CQI) reports. A-HARQ also increases the number of RTX within a 4 ms time period, by utilising Transmission Time Interval (TTI) bundling to decrease the delay incurred from many RTX. A performance analysis is conducted, where A-HARQ was shown to have about 35% lower delay than the legacy HARQ, with a slight decrease in throughput, for low Signal-to-Noise (SNR) values.

Original languageEnglish
Title of host publication2017 IEEE 85th Vehicular Technology Conference (VTC Spring)
Subtitle of host publicationproceedings
Place of PublicationPiscataway, NJ
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages6
ISBN (Electronic)9781509059324, 9781509059317
ISBN (Print)9781509059331
Publication statusPublished - 2017
Event85th IEEE Vehicular Technology Conference, VTC Spring 2017 - Sydney, Australia
Duration: 4 Jun 20177 Jun 2017


Conference85th IEEE Vehicular Technology Conference, VTC Spring 2017


  • hybrid ARQ (HARQ)
  • ultra-reliable communication (URC)
  • ultra-low latency
  • adaptive
  • 5G


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