Efficient design of spectrum-sensing and power control plays a key role in maximizing the throughput of a cognitive radio (CR) network while protecting the PUs from undue interference. In this paper, we consider the problem of joint spectrum-sensing-duration design and power control in a point-to-point CR link. The objective of the proposed solution is to maximize the CR achievable throughput while keeping the CR interference to the primary user (PU) at or below a preset interference threshold. The joint spectrum-sensing design and power control is a non-convex optimization problem, hence, obtaining the optimal solution may not be always feasible. In this paper, we formulate the joint sensing-duration design and power control problem as a two-stage stochastic program with recourse. Afterward, we derive the formulas for the achievable throughput as a function of the sensing duration. Moreover, we investigate the effect of different levels of knowledge of the interference channel state information (CSI) on the achievable throughput and the optimal sensing duration.

This paper investigates the problem of downlink power allocation in a Cognitive Radio (CR) network that operates by opportunistically utilizing vacant licensed Primary User (PU)spectrum, where it is assumed the PU employs an OFDMA scheme. We first analyze the interference to the PU caused by the CR network due to imperfect spectrum sensing and out-of-band (OOB) emissions from CR subcarrier side-lobes. The power allocation algorithm aims to maximize the CR network capacity under interference constraints, while considering the effect of spectrum sensing errors such as false alarm and misdetection probabilities. The power allocation solution for a single-user CR network is the waterfilling criteria with a variable water level in different subcarriers. For a multiple-user CR network, we employ a heuristic algorithm to solve the power allocation problem, with a significantly reduced computational complexity as compared to the optimal solution.

This paper investigates the problem of uplink subcarrier and power allocation in a Cognitive Radio (CR) network that operates opportunistically within vacant licensed Primary Users (PUs)spectrum. The resource allocation algorithm aims to maximize the CR network throughput under PUs interference constraints. In this paper, CR interference introduced into PUs sub-bands is modeled as a composite of two parts; CR Out-of-Band (OOB) emissions and the interference arising as a result of imperfect spectrum sensing. The uplink subcarrier and power allocation is a Mixed Integer Nonlinear Programming (MINLP) problem, for which obtaining the optimal solution is known to be NP-Hard. In this paper, we propose a three steps heuristic solution to the uplink resource allocation problem. We show through simulation that the proposed algorithm exhibits near-optimal performance and comes with a significant reduction in computational complexity when compared to that of obtaining the optimal solution.

Cognitive radio (CR) has been suggested as a method for promoting more efficient spectrum usage through the principles of spectrum sensing and dynamic spectrum management. The IEEE 802.22 working group in particular is developing a wireless regional-area network (WRAN) standard that will employ unlicensed CR devices operating on a noninterfering basis in the commercial broadcast television (TV) bands. Before such TV-band CR networks can be deployed, the maximum levels of first adjacent and taboo channel interference that a digital television (DTV) receiver can tolerate must be determined. In this context, we will first provide an overview of the IEEE 802.22 WRAN system. Afterwards, we will report on an experimental study that was undertaken to characterize IEEE 802.22 WRAN interference limits into Advanced Television Systems Committee (ATSC) based DTV receivers. Lastly, we will discuss the implications of these WRAN interference limits in terms of the maximum allowable radiated power and out-of-band emission limits that are imposed on WRAN end-user devices.