Steady-State Rate-Optimal Power Adaptation in Energy Harvesting Opportunistic Cognitive Radios with Spectrum Sensing and Channel Estimation Errors

TL;DR

This paper develops a power adaptation strategy for energy-harvesting cognitive radios that maximizes data rates while managing spectrum sensing and channel estimation errors, balancing energy use and harvesting.

Contribution

It introduces a parameterized power control scheme for energy-harvesting secondary users, optimizing sum-rate bounds under realistic sensing and estimation errors.

Findings

Optimized power control parameters maximize sum-rate lower bounds.

Proposed strategy effectively balances energy harvesting and consumption.

Simulation results validate the theoretical analysis and trade-offs.

Abstract

We consider an opportunistic cognitive radio network, consisting of Nu secondary users (SUs) and an access point (AP), that can access a spectrum band licensed to a primary user. Each SU is capable of harvesting energy, and is equipped with a finite size battery, for energy storage. The SUs operate under a time-slotted scheme, where each time slot consists of three non-overlapping phases: spectrum sensing phase, channel probing phase, and data transmission phase. The AP feeds back its estimates of fading coefficients of SUs-AP link to SUs. To strike a balance between the energy harvesting and the energy consumption, we propose a parameterized power control strategy that allows each SU to adapt its power, according to the feedback information and its stored energy. Modeling the randomly arriving energy packets during a time slot as a Poisson process, we establish a lower bound on the achievable sum-rate of SUs-AP links, in the presence of both spectrum sensing and channel estimation errors. We optimize the parameters of the proposed power control strategy, such that the derived sum-rate lower bound is maximized, subject to an interference constraint. Via simulations, we corroborate our analysis and explore spectrum sensing-channel probing-data transmission trade-offs.