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Effective Capacity Analysis of H-ARQ Assisted Cooperative Communication Systems

Mokhtar Bouteggui, Fatiha Merazka, Gunes Karabulut Kurt

TL;DR

This work develops a recurrence-relations framework to quantify the effective capacity of cooperative CC systems employing HARQ with arbitrary channel distributions and retransmission counts over asymmetric channels. It derives closed-form EC expressions for two retransmission strategies (lossless ARQ and truncated HARQ) and both HARQ-RR and HARQ-IR, with a Rayleigh fading example to illustrate outage and EC behavior. Key findings show EC saturates with a small number of retransmissions, while the optimal relay participation depends on link qualities, QoS constraints, and the data rate; HARQ-IR often outperforms HARQ-RR, particularly at higher R and θ. The results provide QoS-aware design guidance for CC systems, including how to allocate retransmissions between source and relay under varying channel conditions and QoS requirements.

Abstract

In this paper, the effective capacity of cooperative communication (CC) systems with hybrid Automatic repeat request (HARQ) is derived. The derived expressions are valid for any channel distribution and with any arbitrary number of retransmissions by the source and relay for both HARQ-repetition redundancy (RR) and HARQ-incremental redundancy (IR) over asymmetric channels. As an example, we use the derived EC expression over Rayleigh fading channels. Several results are obtained for a low rate and signal-to-noise ratio (SNR). We can see that the EC attends its maximum value with a small number of retransmissions. As expected when the relay-destination channel has low SNR, it is better than the relay does not participate especially when we assign a large number of transitions at the relay. For high data rates and strict quality of service (QoS) constraints, it is better to increase the number of relay transmissions. Finally, when we increase the number of source retransmissions, the effective capacity improves even for low values.

Effective Capacity Analysis of H-ARQ Assisted Cooperative Communication Systems

TL;DR

This work develops a recurrence-relations framework to quantify the effective capacity of cooperative CC systems employing HARQ with arbitrary channel distributions and retransmission counts over asymmetric channels. It derives closed-form EC expressions for two retransmission strategies (lossless ARQ and truncated HARQ) and both HARQ-RR and HARQ-IR, with a Rayleigh fading example to illustrate outage and EC behavior. Key findings show EC saturates with a small number of retransmissions, while the optimal relay participation depends on link qualities, QoS constraints, and the data rate; HARQ-IR often outperforms HARQ-RR, particularly at higher R and θ. The results provide QoS-aware design guidance for CC systems, including how to allocate retransmissions between source and relay under varying channel conditions and QoS requirements.

Abstract

In this paper, the effective capacity of cooperative communication (CC) systems with hybrid Automatic repeat request (HARQ) is derived. The derived expressions are valid for any channel distribution and with any arbitrary number of retransmissions by the source and relay for both HARQ-repetition redundancy (RR) and HARQ-incremental redundancy (IR) over asymmetric channels. As an example, we use the derived EC expression over Rayleigh fading channels. Several results are obtained for a low rate and signal-to-noise ratio (SNR). We can see that the EC attends its maximum value with a small number of retransmissions. As expected when the relay-destination channel has low SNR, it is better than the relay does not participate especially when we assign a large number of transitions at the relay. For high data rates and strict quality of service (QoS) constraints, it is better to increase the number of relay transmissions. Finally, when we increase the number of source retransmissions, the effective capacity improves even for low values.
Paper Structure (23 sections, 5 theorems, 49 equations, 19 figures)

This paper contains 23 sections, 5 theorems, 49 equations, 19 figures.

Table of Contents

  1. Introduction
  2. Assumptions
  3. Notation
  4. System model
  5. System description
  6. Channel model
  7. Effective capacity
  8. QoS Exponent
  9. Recurrence Relation Approach
  10. Effective capacity for CC with retransmission schemes
  11. Strategy I
  12. Strategy II
  13. Application over Rayleigh fading channel
  14. Outage Probability of Strategy I
  15. Outage Probabilities of Strategy II using HARQ-RR
  16. ...and 8 more sections

Key Result

Theorem 1

larsson_effective_2016 For retransmission scheme and transmission rate $R$, with $k \to \infty$, let $S$ be a set with $L$ communication modes, $v\in\{0,1,\cdots v_{max}\}$ communication packets per transmission and $P_{v\tilde{s}s}$ the transition probabilities from communication mode $\tilde{s}$ t where $\lambda_+=\max\{|\lambda_1|,|\lambda_2|,\cdots,|\lambda_{L}|\}$ is the spectral radius of th

Figures (19)

  • Figure : (a)
  • Figure : (a)
  • Figure : (a)
  • Figure : (a)
  • Figure : (a)
  • ...and 14 more figures

Theorems & Definitions (9)

  • Theorem 1
  • Corollary 1
  • proof
  • Corollary 2
  • proof
  • Corollary 3
  • proof
  • Corollary 4
  • proof