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Transmission Delay Minimization for NOMA-Based F-RANs

Yuan Ai, Xidong Mu, Pengbo Si, Yuanwei Liu

TL;DR

A novel non-orthogonal multiple access (NOMA) based low-delay service framework is proposed for fog radio access networks (F-RANs) and significantly outperforms orthogonal multiple access-based F-RANs systems in terms of average transmission delay in different scenarios.

Abstract

A novel non-orthogonal multiple access (NOMA) based low-delay service framework is proposed for fog radio access networks (F-RANs). Fog access points (FAPs) leverage NOMA for local delivery of cached content, while the cloud access point employs NOMA to simultaneously push content to FAPs and directly serve users. Based on this model, a delay minimization problem is formulated by jointly optimizing user association, cache placement, and power allocation. To address this non-convex mixed-integer nonlinear programming problem, an alternating optimization (AO) algorithm is developed, which decomposes the original problem into two subproblems, namely joint user association and cache placement, and power allocation. In particular, a low-complexity algorithm is designed to optimizing the user association and cache placement strategy using the McCormick envelope theory and Lagrangian partial relaxation. The power allocation is optimized by invoking the successive convex approximation. Simulation results reveal that: 1) the proposed AO-based algorithm effectively balances between the achieved performance and computational efficiency, and 2) the proposed NOMA-based F-RANs framework significantly outperforms orthogonal multiple access-based F-RANs systems in terms of average transmission delay in different scenarios.

Transmission Delay Minimization for NOMA-Based F-RANs

TL;DR

A novel non-orthogonal multiple access (NOMA) based low-delay service framework is proposed for fog radio access networks (F-RANs) and significantly outperforms orthogonal multiple access-based F-RANs systems in terms of average transmission delay in different scenarios.

Abstract

A novel non-orthogonal multiple access (NOMA) based low-delay service framework is proposed for fog radio access networks (F-RANs). Fog access points (FAPs) leverage NOMA for local delivery of cached content, while the cloud access point employs NOMA to simultaneously push content to FAPs and directly serve users. Based on this model, a delay minimization problem is formulated by jointly optimizing user association, cache placement, and power allocation. To address this non-convex mixed-integer nonlinear programming problem, an alternating optimization (AO) algorithm is developed, which decomposes the original problem into two subproblems, namely joint user association and cache placement, and power allocation. In particular, a low-complexity algorithm is designed to optimizing the user association and cache placement strategy using the McCormick envelope theory and Lagrangian partial relaxation. The power allocation is optimized by invoking the successive convex approximation. Simulation results reveal that: 1) the proposed AO-based algorithm effectively balances between the achieved performance and computational efficiency, and 2) the proposed NOMA-based F-RANs framework significantly outperforms orthogonal multiple access-based F-RANs systems in terms of average transmission delay in different scenarios.
Paper Structure (21 sections, 53 equations, 7 figures, 4 tables, 2 algorithms)

This paper contains 21 sections, 53 equations, 7 figures, 4 tables, 2 algorithms.

Table of Contents

  1. Introduction
  2. Related Works
  3. Studies on NOMA-based F-RANs
  4. Studies on Low-Delay Optimization
  5. Motivations and Contributions
  6. Organization
  7. System Model
  8. System Description
  9. Cache Model
  10. NOMA-based Communication Model
  11. Transmission from FAP to UE
  12. Transmission from CP to UE
  13. Transmission from CP to FAP
  14. Delay Model
  15. Problem Formulation
  16. ...and 6 more sections

Figures (7)

  • Figure 1: An illustration of the NOMA-based F-RANs.
  • Figure 2: Average delay under different maximum transmission power of FAP
  • Figure 3: Average transmission delay versus FAP maximum transmission power for different schemes.
  • Figure 4: Average transmission delay versus cell radius for different schemes.
  • Figure 5: Average transmission delay versus FAP cache capacity for different schemes.
  • ...and 2 more figures