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Message Replication for Improving Reliability of LR-FHSS Direct-to-Satellite IoT

Sonu Rathi, Siddhartha S. Borkotoky

TL;DR

This paper tackles uplink reliability in LR-FHSS for direct-to-satellite IoT by introducing two message-replication schemes. It demonstrates, through analysis and simulations, that frame replication and fragment replication can significantly improve the message delivery probability $MDP$ without receiver acknowledgments, with the best choice depending on traffic density and data rate. The work provides concrete guidelines: frame replication favors sparse traffic, while fragment replication with DR9 excels under heavier traffic, albeit with higher energy expenditure. The findings offer a scalable, hardware-friendly approach to boost D2S-IoT reliability, enabling practical deployment without modifying receivers or introducing advanced coding. Future work includes practical fragment-recovery techniques and incorporating fading, shadowing, and capture effects into the analytical framework.

Abstract

Long-range frequency-hopping spread spectrum (LR-FHSS) promises to enhance network capacity by integrating frequency hopping into existing Long Range Wide Area Networks (LoRaWANs). Due to its simplicity and scalability, LR-FHSS has generated significant interest as a potential candidate for direct-to-satellite IoT (D2S-IoT) applications. This paper explores methods to improve the reliability of data transfer on the uplink (i.e., from terrestrial IoT nodes to satellite) of LR-FHSS D2S-IoT networks. Because D2S-IoT networks are expected to support large numbers of potentially uncoordinated IoT devices per satellite, acknowledgment-cum-retransmission-aided reliability mechanisms are not suitable due to their lack of scalability. We therefore leverage message-replication, wherein every application-layer message is transmitted multiple times to improve the probability of reception without the use of receiver acknowledgments. We propose two message-replication schemes. One scheme is based on conventional replication, where multiple replicas of a message are transmitted, each as a separate link-layer frame. In the other scheme, multiple copies of a message is included in the payload of a single link-layer frame. We show that both techniques improve LR-FHSS reliability. Which method is more suitable depends on the network's traffic characteristics. We provide guidelines to choose the optimal method.

Message Replication for Improving Reliability of LR-FHSS Direct-to-Satellite IoT

TL;DR

This paper tackles uplink reliability in LR-FHSS for direct-to-satellite IoT by introducing two message-replication schemes. It demonstrates, through analysis and simulations, that frame replication and fragment replication can significantly improve the message delivery probability without receiver acknowledgments, with the best choice depending on traffic density and data rate. The work provides concrete guidelines: frame replication favors sparse traffic, while fragment replication with DR9 excels under heavier traffic, albeit with higher energy expenditure. The findings offer a scalable, hardware-friendly approach to boost D2S-IoT reliability, enabling practical deployment without modifying receivers or introducing advanced coding. Future work includes practical fragment-recovery techniques and incorporating fading, shadowing, and capture effects into the analytical framework.

Abstract

Long-range frequency-hopping spread spectrum (LR-FHSS) promises to enhance network capacity by integrating frequency hopping into existing Long Range Wide Area Networks (LoRaWANs). Due to its simplicity and scalability, LR-FHSS has generated significant interest as a potential candidate for direct-to-satellite IoT (D2S-IoT) applications. This paper explores methods to improve the reliability of data transfer on the uplink (i.e., from terrestrial IoT nodes to satellite) of LR-FHSS D2S-IoT networks. Because D2S-IoT networks are expected to support large numbers of potentially uncoordinated IoT devices per satellite, acknowledgment-cum-retransmission-aided reliability mechanisms are not suitable due to their lack of scalability. We therefore leverage message-replication, wherein every application-layer message is transmitted multiple times to improve the probability of reception without the use of receiver acknowledgments. We propose two message-replication schemes. One scheme is based on conventional replication, where multiple replicas of a message are transmitted, each as a separate link-layer frame. In the other scheme, multiple copies of a message is included in the payload of a single link-layer frame. We show that both techniques improve LR-FHSS reliability. Which method is more suitable depends on the network's traffic characteristics. We provide guidelines to choose the optimal method.
Paper Structure (16 sections, 14 equations, 5 figures)

This paper contains 16 sections, 14 equations, 5 figures.

Table of Contents

  1. Introduction
  2. Related Works
  3. LR-FHSS
  4. Message Replication
  5. Our Contributions vis-á-vis Related Work
  6. LR-FHSS Transmissions
  7. Proposed Message-Replication Schemes
  8. Frame Replication
  9. Fragment Replication
  10. System Model
  11. Message Delivery Probability
  12. Frame Replication
  13. Fragment replication
  14. Energy Efficiency
  15. Numerical Results
  16. ...and 1 more sections

Figures (5)

  • Figure 1: Illustration of replication mechanisms for a message comprising fragments F1 through F4. A header replica is denoted by H.
  • Figure 2: Comparison of message-delivery probabilities.
  • Figure 3: Reliability comparison of different combinations of data rates and replication schemes.
  • Figure 4: Energy efficiency (messages/joule) for different combinations of data rates and replication schemes.
  • Figure 5: Performance comparison of different replication strategies for a traffic of 8 messages per node per hour.