Cognitive radio: survey on communication protocols, spectrum decision issues, and future research directions

Abstract

Currently, the radio spectrum is statically allocated and divided between licensed and unlicensed frequencies. Due to this inflexible policy, some frequency bands are growing in scarcity, while large portions of the entire radio spectrum remain unused independently of time and location. Cognitive Radio is a recent network paradigm that aims a more flexible and efficient usage of the radio spectrum. Basically, it allows wireless devices to opportunistically access portions of the entire radio spectrum without causing any harmful interference to licensed users. The present document surveys the literature on Cognitive Radio. It aims to provide a comprehensive and self-contained description of this research topic area, mainly focusing on communication protocols, spectrum decision issues, and future research directions. It is a tutorial in nature and consequently does not require any previous knowledge about Cognitive Radio. Readers are only required to have some general background on wireless data networks. Emphasis is put on Cognitive Radio genesis, issues that must be addressed, related technologies, standardization efforts, the state of the art, and future research directions according to the vision of the authors.

Parallel Cyclostationarity-Exploiting Algorithm for Energy-Efficient Spectrum Sensing

“…In recent years, Cognitive Radio (CR) has established itself as reality in the evolution of wireless communications systems [1], [2], serving as an alternative to tackle the shortage of spectrum [3], [4].…”

A Survey of Contention Based Medium Access Control (Mac) Protocols in Wireless Lan

“…In order to prevents the contention window from expand too large or reduce too small two boundaries known as CWmin and CWmax are introduced in IEEE 802.11 standard. The CW is dynamically controlled by the back-off algorithm, namely Binary Exponential Back-off (BEB) in the IEEE 802.11 DCF scheme [8].…”

Joint Spatial-Temporal Access Scheme for Multihop Cognitive Relay Networks Over Nakagami-m Fading

“…The main advantages of cooperative CRNs include low transmit power with small interference to the primary users (PUs), efficient spectrum utilization, flexible connectivity and coverage, large throughput and high reliability [1]. Currently, the cognitive users (CUs) in cooperative CRNs mainly work in two modes, namely, overlay and underlay [2].…”