Towards cognitive radio networks: Spectrum utilization measurements in suburb environment

Abstract

This paper deals with spectrum utilization measurements in the frequency band from 100 MHz up to 3 GHz. The measurement is based on the energy detection principle using wideband logarithmically periodic antenna. The results point out the fact, that the frequency spectrum is not utilized in an optimal manner and that there do exist less or more utilized licensed frequency bands that could be possibly used by cognitive radios in an opportunistic way. Cognitive radio concept for better spectrum utilization is introduced here along with an overall approach regarding spectrum utilization in the next generation wireless networks.Index Terms -Cognitive radio, radio spectrum management, spectrum sensing, spectrum utilization.

Analysis of Cooperation for Relay based Spectrum Sensing in Cognitive Radio Networks

“…The fusion center functions as a base station, which manages the cognitive radio network as well as all the associated cognitive users. When a primary signal, x (t ) , is transmitted through a wireless channel, the received signal at the fusion center, y (t) , can be given as (1) where ni (t) is the additive white Gaussian noise (A WGN) signal from the i-th user with zero mean and variance a-; , n (t) is A WGN signal at the base station with zero mean and variance a2, hi is the corresponding amplifying gain at the i-th user. The hypothesis Ho represent the absence of the primary signal, while the hypothesis HI represent the presence of the primary signal.…”

“…Ra dio spectrum has become a precious and limited resource. This is evident by many measurements [1]- [3], which ex poses that almost all frequency bands have been assigned for licensed users, and there is little new spectrum band available for emerging wireless products and services. Fortunately, cognitive radio provides a promising solution to solve the problem of spectrum shortage.…”

An Improved Clustering Cooperative Spectrum Sensing Algorithm

“…Cognitive radio is an effective solution scheme for spectrum sharing [1], spectrum sensing is one of key technologies of cognitive radio network [2,3], which main function is to detect idle frequency band named the spectrum hole. Meanwhile, the detection technology also requires the ability to quickly identify authorized users (AU), so that the cognitive users can stop to use the band immediately when authorized users emerge, and ensure the cognitive users to authorized users communicate without causing interference.…”

“…Traditional double-threshold energy detection [3] is one of key technologies of spectrum sensing, as shown in Fig. 35.1, there are two thresholds λ L and λ H , E k denotes the signal energy which is the kth cognitive user received.…”

“…This paper also improves double-threshold detection, each cognitive user within a cluster adopt improved double-threshold energy detection locally. The detective performance of improved cooperative spectrum detection algorithm has been greatly improved compare with the algorithm that cooperative spectrum sensing based on traditional double threshold detection [3,4].…”