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Related papers
Cognitive radio for TVWS usage
TELKOMNIKA Telecommunication Computing Electronics and Control, 2019
Spectrum scarcity is an emerging issue in wireless communication systems due to the increasing demand of broadband services like mobile communications, wireless internet access, IoT applications, among others. The migration of analog TV to digital systems (a.k.a. digital TV switchover) has led to the release of a significant spectrum share that can be used to support said additional services. Likewise, TV white spaces emerge as spectral opportunities that can also be explored. Hence, cognitive radio (CR) presents itself as a feasible approach to efficiently use resources and exploit gaps within the spectrum. The goal of this paper is to unveil the state of the art revolving around the usage of TV white spaces, including some of the most important methods developed to exploit such spaces, upcoming opportunities, challenges for future research projects, and suggestions to improve current models.
Energy-Efficient Frequency and Power Allocation for Cognitive Radios in Television Systems
—Energy-efficient resource allocation for cognitive radios operating in television systems (TV white spaces) presents a unique challenge compared with other cognitive radios because the interference constraint is for the whole frequency band rather than per carrier. This paper presents a subchannel and power allocation protocol that maximizes the energy efficiency (EE) of transmissions from a cognitive base station operating in the TV white spaces. The system model conforms to the IEEE 802.22 standard , and the proposed two-step solution to the EE maximization problem satisfies users' minimum rate requirements and keeps the interference to the primary users in the neighboring areas below a specified threshold. The first step of the protocol is a near-optimal but low-complexity subchannel assignment. This is followed by an optimal power allocation procedure that is obtained by analyzing the Karush–Kuhn–Tucker conditions. The computational complexity of the resulting resource allocation protocol is the same as that of the least complex resource allocation protocol for orthogonal frequency division multiple access (OFDMA) downlinks in the literature. Simulation results show that our protocol achieves higher EE compared with a modified and improved version of the OFDMA protocol from the literature.
A survey of cognitive radio access to TV White Spaces
2009 International Conference on Ultra Modern Telecommunications & Workshops, 2009
Cognitive radio is being intensively researched as the enabling technology for license-exempt access to the so-called TV White Spaces (TVWS), large portions of spectrum in the UHF/VHF bands which become available on a geographical basis after digital switchover. Both in the US, and more recently, in the UK the regulators have given conditional endorsement to this new mode of access. This paper reviews the state-of-the-art in technology, regulation, and standardisation of cognitive access to TVWS. It examines the spectrum opportunity and commercial use cases associated with this form of secondary access.
TV White Spaces exploitation utilizing a Cognitive Radio system based on DVB-H
2011
The transition from analogue to digital terrestrial television (i.e. Digital Switchover - DSO) releases a significant amount of valuable spectrum (i.e. Digital Dividend), in UHF band. Digital Dividend will be available in the form of a “cleared spectrum” of contiguous channels, as well as in the form of “interleaved spectrum”, namely TV White Spaces (i.e. TVWS), unused within given geographical locations, in order to avoid causing interference to co-channel or adjacent channel DVB-T transmitters. “Cleared spectrum” and TVWS provide an opportunity to deploy Cognitive Radio (CR) networks, able to operate in UHF band, by sharing the available spectrum with other licensed systems. In this context, this paper elaborates on the efficient sharing of TVWS by proposing a mobile TV network with CR capabilities, based on DVB-H. The proposed network operates as an unlicensed secondary system, accessing TVWS via a spectrum broker, which is in charge of assigning the available spectrum.
Using TV receiver information to increase cognitive white space spectrum
2012 IEEE International Symposium on Dynamic Spectrum Access Networks, 2012
In this paper we investigate the usage of cognitive radio devices within the service area of TV broadcast stations. Until now the main approach for a cognitive radio to operate in the TV bands has been to register TV broadcast stations locations and thus protecting the broadcast stations service area. Through information about TV receivers location, we show that a cognitive radio should be able to operate within this service area without causing harmful interference to the TV receivers as defined by Ofcom and FCC. We provide simulations based on real statistics from Norway that show that especially in rural areas TV receiver registration can provide a substantial gain in terms of exploitable frequencies for a cognitive radio.
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/techniques-for-detection-of-analog-tv-whitespace-in-electromagnetic-spectrum-for-cognitive-radio-applications https://www.ijert.org/research/techniques-for-detection-of-analog-tv-whitespace-in-electromagnetic-spectrum-for-cognitive-radio-applications-IJERTV2IS70245.pdf Spectrum sensing is the key to the success of cognitive radios (CRs), which detect whether a primary user is utilizing his allocated transmission channel or not, before itself launching transmission. Thus secondary users, who use CR, will use the primary user's channel without harmfully interfering with his/her signal. In this paper, the most commonly used detection techniques namely Energy detection, Matched filter detection and Cyclo-stationary detection techniques are studied in the context of using analog TV channels for CR application. The cyclostationary detection technique outperforms the other two by detecting the presence of primary user's signal on a channel with signal to noise ratio (SNR) worse by more than 20dB, relative to the SNR thresholds of other two techniques. The evaluation of 3 detection techniques is done under a wide range of signal threshold (λ) relative to noise. This study helps in gaining a deeper insight into the use of analog TV channels for CR applications.
Tunable Antenna Design for Cognitive Radios in the UHF TV Band
International Journal of Mobile Network Communications & Telematics, 2013
Presently, Ultra Wide Band (UWB) radio technology has attracted much interest in academics, industrial and standardization (IEEE) activities. UWB characterizes transmission systems with instantaneous spectral occupancy of higher bandwidth or higher fractional bandwidth. The antenna is one of the overlooked part of a RF (Radio Frequency) design. The range, performance, and legality of a RF link are significantly dependent upon the antenna. The UHF (Ultra High Frequency) TV Band is exclusively addressed in IEEE802.22 standardization. The UHF TV band is 336MHz wider according to CCIR (Consultative Committee on International Radio) standards. One major challenge in designing a UWB antenna for UHF band is limiting the physical size of the antenna. Authors have previously illustrated the design, implementation and testing of a UWB antenna for cognitive radios in the UHF TV Band[1]. Although it gives better results, performances at lower frequencies are slightly below than the higher frequencies. This problem can be rectified by introducing an impedance matching circuit at particular frequencies. Since it is required to cover a wider bandwidth several matching circuits could be introduced, but it is not practical because of size, complexity, losses, Electromagnetic interferences (EMI) and cost. Therefore this paper presents a simple and low cost Tuneable Antenna design which is controlled by software instructions. Hence this antenna design can be used in implementing cognitive radios in the UHF TV Band.
Feasibility of Dynamic Spectrum Access in Underutilized Television Bands
2007 2nd IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, 2007
This paper presents the preliminary results from a feasibility study regarding the operation of secondary spectrum users within unused television spectrum. Television spectrum is known within the wireless communications community as being underutilized, making it a prime candidate for dynamic spectrum access. Nevertheless, the quality of this spectrum for enabling secondary transmissions has never been assessed. Two unique scenarios are examined:(i) the possibility of unlicensed devices interfering with digital TV reception, and (ii) the possibility of secondary users experiencing interference when operating within close proximity to television towers. With respect to the former, we investigate the critical operating parameters for developing the technical rules for device operation in bands adjacent to a digital television transmission. Regarding the latter, we examine, via measurement campaign, how non-ideal transmission properties of television broadcasts, including intermodulation and saturation effects, can potentially impair the performance of secondary transmissions.