A survey on MAC protocols for complex self-organizing cognitive radio networks

Complex self-organizing cognitive radio (CR) networks serve as a framework for accessing the spectrum allocation dynamically where the vacant channels can be used by CR nodes opportunistically. CR devices must be capable of exploiting spectrum opportunities and exchanging control information over a control channel. Moreover, CR nodes should intelligently coordinate their access between different cognitive radios to avoid collisions on the available spectrum channels and to vacate the channel for the licensed user in timely manner. Since inception of CR technology, several MAC protocols have been designed and developed. This paper surveys the state of the art on tools, technologies and taxonomy of complex self-organizing CR networks. A detailed analysis on CR MAC protocols form part of this paper. We group existing approaches for development of CR MAC protocols and classify them into different categories and provide performance analysis and comparison of different protocols. With our categorization, an easy and concise view of underlying models for development of a CR MAC protocol is provided

An Overview of Spectrum Occupancy Models for Cognitive Radio Networks

Part 1: - PE-CRN 2011 WorkshopInternational audienceThe Dynamic Spectrum Access (DSA) paradigm based on the Cognitive Radio (CR) technology has emerged as a promising solution to conciliate the existing conflicts between spectrum demand growth and current spectrum underutilization without changes to the existing legacy wireless systems. The basic underlying idea of DSA/CR is to allow unlicensed users to access in an opportunistic and non-interfering manner some licensed bands temporarily unused by the licensed users. Due to the opportunistic nature of the DSA/CR paradigm, a realistic and accurate modeling of spectrum occupancy patterns becomes essential in the domain of DSA/CR research. In this context, this paper provides an overview of the existing spectrum occupancy models recently proposed in the literature to characterize the spectrum usage patterns of licensed systems in the time, frequency and space dimensions

Discrete Time Analysis of Cognitive Radio Networks with Saturated Source of Secondary Users

Part 1: - PE-CRN 2011 WorkshopInternational audienceThe strategy used for sensing in a cognitive radio network affects the white space that secondary users (SUs) perceive and hence their throughput. For example, let the average time interval between consecutive sensing be fixed as τ. There are several possible ways to achieve this mean value. The SU may sense the channel at equal intervals of length τ or sense it at randomly spaced intervals with mean value τ and guided by, for example, geometric distribution, uniform distribution, etc. In the end the strategy selected does affect the available white space and throughput as well as the resources spent on sensing. In this paper we present a discrete time Markov chain model for cognitive radio network and use it to obtain the efficiency of sensing strategies. The system studied is one in which we have a saturated source of secondary users. These assumptions do not in any ways affect our results

Maximizing lifetime of connected-dominating-set in cognitive radio networks

Abstract. Connected-dominating-set (CDS) is a representative technique for constructing a virtual backbone of wireless networks. Most of existing works on CDS aim at minimizing the size of the CDS, i.e., constructing the minimum CDS (MCDS), so as to reduce the communication overhead over the CDS. However, MCDS may not work well in cognitive radio networks (CRNs) where communication links are prone to failure due to the unpredictable activities of primary users. A MCDS without consideration of stochastic activities of primary users easily becomes invalid when the primary users reclaim the licensed spectrum. In this work, we assume that the activities of primary users follow the exponential distribution. Our problem is to maximize the lifetime of the CDS while minimizing the size of the CDS, where the lifetime of a CDS is defined as the expected duration that the CDS is maintained valid. We show that the problem is NP-hard and propose a three-phase algorithm. Our basic idea is to apply a pruning-based approach to maximize the lifetime of the CDS. Given a CRN, we prove that our algorithm can compute a CDS such that i) the lifetime of the CDS is maximized (optimal); and ii) the size of the CDS is upper-bounded. To the best of our knowledge, it is the first time in the literature that CDS in CRNs is studied and an effective algorithm is proposed

Spectrum usage models for the analysis, design and simulation of cognitive radio networks

This chapter presents a comprehensive set of spectrum occupancy models specifically envisaged for the analysis, design and simulation of cognitive radio systems. The presented models have been proven to accurately capture and reproduce the statistical properties of spectrum occupancy patterns in real systems. The chapter begins with the description of various time-dimension modeling approaches (in discrete and continuous time) along with models for time-correlation properties. Subsequently, joint time-frequency models as well as space-dimension models are explained in detail. Finally, the chapter concludes with a discussion on the combination and integration of the presented models into a unified modeling approach where the time, frequency and space dimensions of spectrum usage can be modeled simultaneously.Peer ReviewedPostprint (published version