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Multi-hop Relaying with Mixed Half and Full Duplex Relays for Offloading to MEC

Pavel Mach, Zdenek Becvar, Mohammadsaleh Nikooroo

TL;DR

This work tackles offloading computational tasks from a UE to an MEC server via multi-hop relaying with energy-constrained relays. It casts the problem as a sum-energy minimization under a time constraint and introduces three relaying configurations that mix half- and full-duplex operation. Each configuration is shown to be convex and solvable with standard convex optimization (CVX), yielding notable gains in meeting the processing-time deadline and reducing energy consumption compared with non-optimized baselines. The results indicate improvements up to $38\%$ in deadline satisfaction and up to $28\%$ energy savings, illustrating the practical potential of mixed duplex relays for energy-efficient MEC offloading.

Abstract

In this paper, we focus on offloading a computing task from a user equipment (UE) to a multi-access edge computing (MEC) server via multi-hop relaying. We assume a general relaying case where relays are energy-constrained devices, such as other UEs, internet of things (IoT) devices, or unmanned aerial vehicles. To this end, we formulate the problem as a minimization of the sum energy consumed by the energy-constrained devices under the constraint on the maximum requested time of the task processing. Then, we propose a multi-hop relaying combining half and full duplexes at each individual relay involved in the offloading. We proof that the proposed multi-hop relaying is convex, thus it can be optimized by conventional convex optimization methods. We show our proposal outperforms existing multi-hop relaying schemes in terms of probability that tasks are processed within required time by up to 38\% and, at the same time, decreases energy consumption by up to 28%.

Multi-hop Relaying with Mixed Half and Full Duplex Relays for Offloading to MEC

TL;DR

This work tackles offloading computational tasks from a UE to an MEC server via multi-hop relaying with energy-constrained relays. It casts the problem as a sum-energy minimization under a time constraint and introduces three relaying configurations that mix half- and full-duplex operation. Each configuration is shown to be convex and solvable with standard convex optimization (CVX), yielding notable gains in meeting the processing-time deadline and reducing energy consumption compared with non-optimized baselines. The results indicate improvements up to in deadline satisfaction and up to energy savings, illustrating the practical potential of mixed duplex relays for energy-efficient MEC offloading.

Abstract

In this paper, we focus on offloading a computing task from a user equipment (UE) to a multi-access edge computing (MEC) server via multi-hop relaying. We assume a general relaying case where relays are energy-constrained devices, such as other UEs, internet of things (IoT) devices, or unmanned aerial vehicles. To this end, we formulate the problem as a minimization of the sum energy consumed by the energy-constrained devices under the constraint on the maximum requested time of the task processing. Then, we propose a multi-hop relaying combining half and full duplexes at each individual relay involved in the offloading. We proof that the proposed multi-hop relaying is convex, thus it can be optimized by conventional convex optimization methods. We show our proposal outperforms existing multi-hop relaying schemes in terms of probability that tasks are processed within required time by up to 38\% and, at the same time, decreases energy consumption by up to 28%.
Paper Structure (17 sections, 3 theorems, 27 equations, 6 figures, 1 table)

This paper contains 17 sections, 3 theorems, 27 equations, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. System Model
  3. Network model
  4. Communication and relaying models
  5. HD
  6. FD--Orthogonal
  7. FD--Shared
  8. Computing model
  9. Problem formulation
  10. Optimization of multi-hop relaying
  11. HD+HD relaying case
  12. HD+FD--Orthogonal relaying case
  13. HD+FD--Shared relaying case
  14. Performance evaluation
  15. Simulation models and parameters
  16. ...and 2 more sections

Key Result

Lemma 1

The optimization problem in (P1) and all its constraints are convex with respect to $\boldsymbol{\mathcal{T}}$.

Figures (6)

  • Figure 1: System model with one UE having a task to offload via multi-hop relaying and computed at MEC server.
  • Figure 2: Optimization of HD+HD by setting of each $t_{n}^{hd}$.
  • Figure 3: Optimization of HD+FD - Orthogonal bandwidth by jointly setting $t_{1}^{hd}$, $t_{2}^{fd_o}$, $b_{2}$, and $b_{3}$.
  • Figure 4: Optimization of HD+FD - Shared bandwidth by setting $t_{1}^{hd}$ and $t_{2}^{fd_s}$.
  • Figure 5: Simulation scenario.
  • ...and 1 more figures

Theorems & Definitions (6)

  • Lemma 1
  • proof
  • Lemma 2
  • proof
  • Lemma 3
  • proof