Comparison of spectrum occupancy measurements using software defined radio RTL-SDR with a conventional spectrum analyzer approach

In the present day Cognitive Radio has become a realistic option for solution of the spectrum scarcity problem in wireless communication. Recently, the TV band has attracted attention due to the considerable potential for exploitation of available TV white space which is not utilized based on time and location. In this paper, we investigate spectrum occupancy of the UHF TV band in the frequency range from 470 to 862MHz by using two different devices, the low cost device RTL-SDR and high cost spectrum analyzer. The spectrum occupancy measurements provide evidence of the utility of using the inexpensive RTL SDR and illustrate its effectiveness for detection of the percentage of spectrum utilization compared with results from the conventional high cost Agilent spectrum analyzer, both systems employing various antennas

Experimental detection using cyclostationary feature detectors for cognitive radios

© 2014 IEEE. Signal detection is widely used in many applications. Some examples include Cognitive Radio (CR) and military intelligence. Without guaranteed signal detection, a CR cannot reliably perform its role. Spectrum sensing is currently one of the most challenging problems in cognitive radio design because of various factors such as multi-path fading and signal to noise ratio (SNR). In this paper, we particularly focus on the detection method based on cyclostationary feature detectors (CFD) estimation. The advantage of CFD is its relative robustness against noise uncertainty compared with energy detection methods. The experimental result present in this paper show that the cyclostationary feature-based detection can be robust compared to energy-based technique for low SNR levels

Cooperative wideband spectrum sensing with multi-bit hard decision in cognitive radio

Cognitive radio offers an increasingly attractive solution to overcome the underutilization problem. A sensor network based cooperative wideband spectrum sensing is proposed in this paper. The purpose of the sensor network is to determine the frequencies of the sources and reduced the total sensing time using a multi-resolution sensing technique. The final result is computed by data fusion of multi-bit decisions made by each cooperating secondary user. Simulation results show improved performance in energy efficiency

Spectrum occupancy measurements and lessons learned in the context of cognitive radio

Various measurement campaigns have shown that numerous spectrum bands are vacant even though licenses have been issued by the regulatory agencies. Dynamic spectrum access (DSA) based on Cognitive Radio (CR) has been regarded as a prospective solution to improve spectrum utilization for wireless communications. Empirical measurement of the radio environment to promote understanding of the current spectrum usage of the different wireless services is the first step towards deployment of future CR networks. In this paper we present our spectrum measurement setup and discuss lessons learned during our measurement activities. The main contribution of the paper is to introduce global spectrum occupancy measurements and address the major drawbacks of previous spectrum occupancy studies by providing a unifying methodological framework for future spectrum measurement campaigns

Quality measurements of an UWB reduced-size CPW-fed aperture antenna

The paper presents a characterization of a compact co-planar waveguide (CPW)-fed slot loaded low return loss planar printed antenna designed for wireless communication and ultra-wideband (UWB) applications. Following a review of the antenna design, which was implemented and simulated using Agilent's Advanced Design System (ADS), the paper presents laboratory measurements of relative gain and impulse response transformed from the frequency domain. An antenna quality metric based on time-domain S21 is discussed and related to antenna quality metrics such as the System Fidelity Factor (SFF)

Development of remineralizing, antibacterial dental materials

Light curable methacrylate dental monomers containing reactive calcium phosphate filler (monocalcium phosphate monohydrate (MCPM) with particle diameter of 29 or 90 mu m) and beta-tricalcium phosphate (beta-TCP) at 1: 1 weight ratio in a powder:liquid ratio (PLR) of 1:1 or 3:1 and chlorhexidine diacetate (0 or 5 wt.%), were investigated. Upon light exposure, approximately 90% monomer conversion was gained irrespective of the formulation. Increasing the PLR promoted water sorption by the set material, induced expansion and enhanced calcium, phosphate and chlorhexidine release. Concomitantly, a decline in compressive and biaxial flexural strengths occurred. With a reduction in MCPM particle diameter, however, calcium and phosphate release was reduced and less deterioration in strength observed. After 24 h, the remaining MCPM had reacted with water and beta-TCP, forming, within the set materials, brushite of lower solubility. This provided a novel means to control water sorption, component release and strength properties. Measurable chlorhexidine release was observed for 6 weeks. Both diffusion rate and total percentage of chlorhexidine release decreased with lowering PLR or by adding buffer to the storage solutions. Higher chlorhexidine release was associated with reduced bacterial growth on agar plates and in a biofilm, fermenter. In cell growth media, brushite and hydroxyapatite crystals precipitated on the composite material surfaces. Cells spread on both these crystals and the exposed polymer composite surfaces, indicating their cell compatibility. These formulations could be suitable antibacterial, biocompatible and remineralizing dental adhesives/liners. (C) 2009 Published by Elsevier Ltd. on behalf of Acta Materialia. Inc

Influence of antenna selection on spectrum occupancy measurements in the context of cognitive radio

© 2016 IEEE. Cognitive radio (CR) has been proposed as a solution to the spectrum scarcity problem, which is aggravated by emergence of bandwidth-hungry and feature-rich wireless applications. Selection of appropriate antennas for cognitive radio applications is challenging due to the wide frequency range of operation and the requirement for near-omnidirectional coverage. The objective of this paper is to investigate the influence of antenna selection on spectrum occupancy measurements in the context of cognitive radio. The results presented provide an insight into the influence of antenna selection on actual spectrum utilization in the TV bands

Implementation of combined geolocation database and infrastructure sensing in TV bands using different spectrum devices

—In the present day, the TV Band has become a realistic option and has attracted much attention due to the potential to exploit underutilized TV white space for other communications, based on time and location. In this paper, we design a flexible system which uses a combination of geolocation database and spectrum sensing in the TV band, comparing the performance of different spectrum analyzers (Agilent E4407B, Agilent EXA N9010A and a low cost RTL-SDR) in the real environment

A Spectrum Sensing Test Bed based on Matlab and USRP2

— The spectrum monitoring has gained new aspects with development of the software defined radio SDR as its very important issue in the spectrum management area. In this paper a spectrum monitoring technique with SDR is proposed, the setup of the prototype based on USRP with Matlab is designed and implemented, the spectrum of 2.4-2.5 GHz band has been measured. The result of this prototype has proved that the module is capable of detecting the main radio signal within these bands, moreover this module had to be able to detect and automatically correct the offset resulted between the two USRP devices

Spectrum Occupancy Survey In HULL-UK For Cognitive Radio Applications: Measurement & Analysis

Abstract:- Efficient use of the radio spectrum is a necessity for future wireless systems. Cognitive Radio (CR) systems promise large increases in spectral efficiency. An important design constraint for systems is understanding of the current use of frequency bands which may be used by future CR systems. This paper describes a set of spectrum occupancy measurements performed in Hull, UK, in November 2012 and proposes long-term studies in a single location. Observations provide evidence that the licensed spectrum is far from fully utilized in frequency. Measurements provide evidence of the spectral efficiency benefits that may be accrued by the dynamic reuse of the available spectrum. Such improved usage could break the current spectrum availability bottleneck. The measurement method is based on the energy detection principle