XCopy: boosting weak links for reliable LoRa communication

Xianjin Xia, Qianwu Chen, Ningning Hou, Yuanqing Zheng, Mo Li

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

13 Citations (Scopus)

Abstract

LoRaWAN suffers dramatic performance degradation over a long communication range due to signal attenuation and blockages. To ensure reliable data transfer, LoRaWAN adopts retransmission mechanism where an unacknowledged packet is retransmitted multiple times in the hope of successfully delivering the packet at least once over harsh wireless channels. This retransmission mechanism is ill-suited for LoRa: 1) unsuccessful retransmissions lead to high power consumption for battery-powered LoRa nodes, and 2) a retransmission at another time does not necessarily improve the signal strength over harsh wireless channels.This paper presents the design and implementation of XCopy, which effectively improves the signal strength by coherently combining retransmitted packets received over weak links that would otherwise be thrown away. XCopy develops and puts together novel algorithms to 1) accurately identify the signal copies of the same packet over multiple retransmissions in the presence of interfering packets, and 2) precisely align the signal copies (in time, frequency, and phase) to ensure constructive combining, which turns out to be very challenging in ultra-low SNRs, but made possible by XCopy. Evaluations show that XCopy can deliver significant SNR gains and yield higher packet reception ratio and longer lifetime of LoRa nodes.
Original languageEnglish
Title of host publicationACM MobiCom '23
Subtitle of host publicationproceedings of the 29th Annual International Conference on Mobile Computing and Networking
Place of PublicationNew York
PublisherAssociation for Computing Machinery
Pages194-208
Number of pages15
ISBN (Electronic)9781450399906
DOIs
Publication statusPublished - 2023
Externally publishedYes
Event29th Annual International Conference on Mobile Computing and Networking (ACM MobiCom) - Madrid, Spain
Duration: 2 Oct 20236 Oct 2023

Conference

Conference29th Annual International Conference on Mobile Computing and Networking (ACM MobiCom)
Country/TerritorySpain
CityMadrid
Period2/10/236/10/23

Keywords

  • LoRaWAN
  • reliability
  • coverage
  • retransmission
  • coherent combining

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