Resource allocation in two-way OFDM-based cognitive radio networks with QoE and power consumption guarantees

Weiwei Yang,Xiaohui Zhao

doi:10.1186/s13638-017-1000-6

Abstract

In this paper, a resource allocation algorithm in two-way orthogonal frequency division multiplexing (OFDM) based cognitive radio networks with quality of experience (QoE) and power consumption guarantees is proposed. We define the overall QoE perceived by secondary users (SUs) per power consumption as QoEW. The power consumption model consists of fixed circuit power, dynamic circuit power, and transmit power which depends on the efficiency of the power amplifiers at different terminals. Under the constraint of total maximum transmit power, the optimization objective is to maximize QoEW while meeting the minimum QoE demands of SUs and maintaining interference threshold limitations of multiple primary users. The resource allocation problem is formulated into a nonlinear fractional programming and transformed into an equivalent convex optimization problem via its hypograph form. Based on the Lagrange dual decomposition method and cross-layer (CL) optimization architecture, this convex optimization problem is separately solved in the physical layer and the application layer. The optimal QoEW is achieved through the proposed CL alternate iteration algorithm. Numerical simulation results demonstrate the impacts of system parameters on QoEW and the effectiveness and superiority of the proposed algorithm.

Highlights

Cognitive radio (CR), as a promising technique to solve spectrum scarcity and improve spectrum utilization by means of dynamic spectrum access, has drawn intensive interests in recent years [1]
A power consumption model in wireless networks generally consists of the transmit power which depends on efficiency of power amplifier (PA) at different terminals, fixed circuit power, and dynamic circuit power related to data transmission rate [18]
The objective is to maximize QoEW through joint optimizing power allocation and subcarrier assignment while the following constraints are simultaneously satisfied: (i) in the application layer, quality of experience (QoE) of each secondary users (SUs) should be kept above the minimum mean opinion score (MOS); (ii) in the physical layer, the interference to primary network should be under the interference threshold of each primary users (PUs)-RX in both two time slots, the transmit power of SUs and relay nodes should be below the total maximum power budget, and the exclusiveness of subcarrier assignment should be guaranteed

Summary

Introduction

Cognitive radio (CR), as a promising technique to solve spectrum scarcity and improve spectrum utilization by means of dynamic spectrum access, has drawn intensive interests in recent years [1]. Orthogonal frequency division multiplexing (OFDM) is an effective technique to combat channel fading and multipath loss It has been widely accepted in CR networks (CRNs) owing to its advantages such as spectrum efficiency improvement and dynamic resource allocation. A power consumption model in wireless networks generally consists of the transmit power which depends on efficiency of power amplifier (PA) at different terminals, fixed circuit power, and dynamic circuit power related to data transmission rate [18]. In [19], a QoE-driven resource allocation algorithm in the OFDM system is proposed to address the system energy efficiency and guarantee user-perceived QoE for different multimedia services. Most of the existing resource allocation algorithms adopt the power consumption model ignoring dynamic circuit power and assuming identical efficiency values of PA at different terminals.

System model and problem formulation

Utility-based QoE model

Resource allocation algorithm with QoE and power consumption guarantees

Conclusions