Energy-Efficient Power Allocation in Cognitive Radio Systems with Imperfect Spectrum Sensing

TL;DR

This paper proposes an energy-efficient power allocation method for cognitive radio secondary users that accounts for imperfect spectrum sensing and various levels of channel information, optimizing power use under multiple constraints.

Contribution

It introduces a novel iterative power allocation algorithm based on Dinkelbach's method for maximizing energy efficiency with imperfect spectrum sensing and diverse CSI scenarios.

Findings

Sensing accuracy significantly affects energy efficiency.

Different CSI levels impact optimal power allocation.

Numerical results demonstrate the effectiveness of the proposed method.

Abstract

This paper studies energy-efficient power allocation schemes for secondary users in sensing-based spectrum sharing cognitive radio systems. It is assumed that secondary users first perform channel sensing possibly with errors and then initiate data transmission with different power levels based on sensing decisions. The circuit power is taken into account in total power consumption. In this setting, the optimization problem is to maximize energy efficiency (EE) subject to peak/average transmission power constraints and peak/average interference constraints. By exploiting quasiconcave property of EE maximization problem, the original problem is transformed into an equivalent parameterized concave problem and an iterative power allocation algorithm based on Dinkelbach's method is proposed. The optimal power levels are identified in the presence of different levels of channel side information (CSI) regarding the transmission and interference links at the secondary transmitter, namely perfect CSI of both transmission and interference links, perfect CSI of the transmission link and imperfect CSI of the interference link, imperfect CSI of both links or only statistical CSI of both links. Through numerical results, the impact of sensing performance, different types of CSI availability, and transmit and interference power constraints on the EE of the secondary users is analyzed.