Energy Efficiency Analysis in Modified GoF Spectrum Sensing-Based AF Relay Cooperative Cognitive Sensor Network with Energy Harvesting

Yin Mi,Wenbin Gao,Guangyue Lu,Yinghui Ye

doi:10.1155/2021/3340525

Abstract

In this paper, we propose a joint sensing duration and transmission power allocation scheme to maximize the energy efficiency (EE) of the secondary user (SU) in a cooperative cognitive sensor network (CSN). At the initial time slot of the frame, the secondary transmitter (ST) performs energy harvesting (EH) and spectrum sensing simultaneously using power splitting (PS) protocol. The modified goodness of fit (GoF) spectrum sensing algorithm is employed to detect the licensed spectrum, which is not sensitive to an inaccurate noise power estimate. Based on the imperfect sensing results, the ST will act as an amplify-and-forward (AF) relay and assist in transmission of the primary user (PU) or transmit its own data. The SU’s EE maximization problem is constructed under the constraints of meeting energy causality, sensing reliability, and PU’s quality of service (QoS) requirement. Since the SU’s EE function is a nonconvex problem and difficult to solve, we transform the original problem into a tractable convex one with the aid of Dinkelbach’s method and convex optimization technique by applying a nonlinear fractional programming. The closed-form expression of the ST’s transmission power is also derived through Karush-Kuhn-Tucker (KKT) and gradient method. Simulation results show that our scheme is superior to the existing schemes.

Highlights

With the popularity of wireless devices in the Internet of ings (IoT) [1], it is expected to reach approximately 15.6 billion devices and connections by 2022
In underlay cognitive sensor network (CSN), the secondary user (SU) can be allowed to coexist with the primary user (PU) on the same frequency bands, but it is necessary to ensure that the interference to the primary receiver (PR) does not exceed the tolerance value, and the SUs usually transmit information at a low transmission power to ensure the PU’s quality of service (QoS)
We propose a joint sensing time and power allocation scheme to maximize the SU’s EE in the modified goodness of fit (GoF) spectrum sensing-based cooperative CSN with energy harvesting (EH), where simultaneous EH and spectrum sensing are done at the secondary transmitter (ST) node using power splitting (PS) mode and it can collaborate with PU’s transmission using AF protocol. e major contributions of this paper are summarized as follows: (i) In spectrum sensing-based cooperative CSN with EH, the ST node employs the modified GoF algorithm to detect the PU’s licensed spectrum

Summary

Introduction

With the popularity of wireless devices in the Internet of ings (IoT) [1], it is expected to reach approximately 15.6 billion devices and connections by 2022. In [12], the SU’s EE maximization problem was formulated under energy causality and the PU’s QoS requirement constraint; a joint time and power allocation scheme was proposed in the overlay network. We propose a joint sensing time and power allocation scheme to maximize the SU’s EE in the modified GoF spectrum sensing-based cooperative CSN with EH, where simultaneous EH and spectrum sensing are done at the ST node using PS mode and it can collaborate with PU’s transmission using AF protocol. (iii) Simulations results verify the convergence of our proposed iterative scheme, and considering the linear and nonlinear EH model, we analyse the effect of the ST’s maximal transmission power on the SU’s EE when given different PU’s QoS requirement.

System Model

Problem Formulation and Proposed Solution

Simulation Results

Conclusions