TV White Space Devices Research Articles

Design of a Multimode UWB Antenna Using Characteristic Mode Analysis

In this communication, a low-profile ultrawide band (UWB) antenna is designed, fabricated, and measured for TV white space devices (TVWSDs). Starting from a simple annular ring, the proposed design procedure is guided by the characteristic mode analysis. First, a closed-form estimation to the resonant frequencies of the first two characteristic modes for the annular ring structure is provided. Then, the annular ring is modified to introduce more characteristic modes resonating within the interested spectrum. To excite these modes and to achieve a wideband antenna covering the whole ultrahigh frequency (UHF) TV spectrum, the feeding structure is also carefully designed and refined. Finally, a prototype is fabricated and measured to verify its UWB performance, and radiation patterns at different frequencies are presented to prove the switching of dominating resonating modes. The analyses and performance evaluation show that the proposed antenna is a strong contender to be used for TVWSDs. Furthermore, thanks to the simplicity of tuning and controlling modal resonant frequencies, this procedure can be flexibly applied to various antenna designs.

Prototype of IEEE 802.11af-Based Baseband IC Enabling Compact Device for Wireless Local Area Network Systems in TV White-Spaces

In this paper, we present the world’s first prototype of the IEEE 802.11af-based baseband (BB) integrated circuit (IC) enabling compact, low power consumption and even low cost TV white-space (TVWS) devices. Although it has been already over three years since the IEEE 802.11af was standardized in December 2013 as a wireless local area network (WLAN) system utilizing the TVWS, the IEEE 802.11af-based system has not been commercially deployed yet due to difficulties in downsizing, power saving, cost reduction, etc. As well as conventional WLAN systems, an integration of the BB signal processing circuits is one of the promising technologies that can resolve these concerns. The prototype BB IC incorporates IEEE 802.11af physical layer and low-medium access control functions, buffer memories, and interface circuits, thus enabling easy installation, and easy control by connection to a host device via the universal serial bus interface. In addition, we also develop the compact radio frequency (RF) front-end circuit with variable circuits and filters based on the direct conversion scheme by using an off-the-shelf RF IC. By incorporating the prototype BB IC and the RF front-end circuit, we successfully prototype compact card-type TVWS devices in all-in-one package including an antenna. The practicality of the prototype BB IC is demonstrated by characterizing the card-type TVWS devices in respect to transmission and reception performance and throughput.

Compact low‐profile UWB antenna with characteristic mode analysis for UHF TV white space devices

A compact ultra-high frequency (UHF) ultra-wideband (UWB) antenna for Television TV white space (TVWS) applications is presented in this study. The proposed radiating body is transformed from a rectangular plate following physical essence revealed by characteristic mode analysis. Modal current distributions and their contributions to the total radiation are further analysed after printing the radiating body onto a thin substrate. It is proved that the structure achieves efficient radiation over a wide range of frequencies by exciting multiple modes. In addition, effects of significant parameters on the antenna performance are discussed, and according to which the geometry is optimised. A prototype is fabricated and measured to verify its ultra-wide impedance bandwidth and monopole-like radiation pattern. Realised gain and radiation efficiency over the UHF TV spectrum are also measured. The bandwidth efficiency product against antenna electrical size are analysed and compared with theoretical limit and products of existing designs.

Comprehensive evaluation of an antenna for TV white space devices

In this study, an ultra-high frequency antenna for TV white space devices (TVWSDs) is designed, fabricated and systematically tested. In addition to its radiation efficiency validation using a novel measurement approach, system performance of the antenna is comprehensively studied by integrating it onto different platforms, including a wideband spectrum monitor and a wireless communication client, and testing under realistic scenarios. The performance comparison with a commercial antenna is also performed to demonstrate the effectiveness and robustness of the in house-developed antenna. Overall practical and real-time performance evaluations show that the in-house developed antenna is a strong contender for TVWSDs.

Coexistence of DTV and TV white space systems

SummaryIt is foreseeable that in near future, heterogeneous TV white space (TVWS) systems will operate in underused TV bands. Potential interference between TVWS systems and digital TV (DTV) broadcast system is a major concern. These TVWS systems need to maintain from the DTV service boundary some keep‐out distances dk, which vary depending on circumstances. This work provides a comprehensive analysis on dk for different TVWS devices that operate on co‐ and adjacent channels, based on 2 different protection criteria for DTV service, using 4 different propagation models (each suits different propagation environment) for estimating dk. In brief, this article contributes to the mathematical technique of determining dk under different circumstances. On the basis of the conditions chosen for the analysis, we come up with some recommendations for dk. Moreover, we share our opinions on some regulatory requirements for dk. The strictness of the regulatory requirement in this matter is important because when it is appropriately set, it can actually promote further development and expansion of TVWS technologies.

Enhanced the Accuracy of Specification of Maximum Permitted Emission Levels for TV White Space Devices

In this paper, we present a proposed geo-location database calculations which needs to perform in order to obtain high accuracy of maximum permitted emission levels for TV white space devices (WSDs) operating in the digital terrestrial television (DTT) frequencies. The study is mainly aimed at to analuze the impact of channel power condition in band ( ) and power out band ( ) for WSD for DTT reception in hilly environment under different altitudes. The proposed methodology for the calculation of such emission levels considers the effect of environment and hight of DTT reception. Both theoretical study and mathematical investigations are conducted in order to model and characterize such complex communication medium for WSDs. The propagated maximum permitted emission levels varies from one place to another due to time varying channel condition as a result of obstacles and distance between the transmitter and receiver. The study achieved according to the methodologies, results and recommendations addressed by the European Conference of Postal and Telecommunication administration CEPT. The comparison between proposed model and traditional one has been done by CEPT. The result shows that the proposed model with various altitudes in the hilly terrain environment obtain more accurate maximum permitted emission levels for WSDs, Which increase by 25.609 dBm and 25.61 dBm for and respectively at 100 altitude accordingly.

Coexistence Decision Making for Spectrum Sharing Among Heterogeneous Wireless Systems

This paper focuses on the problem of spectrum sharing between secondary networks that access spectrum opportunistically in TV spectrum. Compared to the coexistence problem in the ISM (Industrial, Scientific and Medical) bands, the coexistence situation in TV whitespace (TVWS) is potentially more complex and challenging due to the signal propagation characteristics in TVWS and the disparity of PHY/MAC strategies employed by the systems coexisting in it. In this paper, we propose a novel decision making algorithm for a system of coexistence mechanisms, such as an IEEE 802.19.1-compliant system, that enables coexistence of dissimilar TVWS networks and devices. Our algorithm outperforms existing coexistence decision making algorithms in terms of fairness, and percentage of demand serviced.

An integrated low power system architecture for spectrum sensing enabled cognitive radios

Continuous rise in the number of users as well as the increased requirement of bandwidth per user has created a need to use the spectrum efficiently. Cognitive radios are solutions proposed to address the problem of using the spectrum efficiently. Regulatory bodies around the world, FCC included, have introduced specifications intended for cognitive radio applications. TV White Space devices, which operate in the spectrum holes caused by transition from analog to digital transmission, were the first targeted applications for cognitive radio specifications (IEEE 802.22, ECMA-392). However, to maximize the potential of the idea of cognitive radios it is desirable to be able to sense the spectrum across a wide band and accordingly transmit ‘smartly’. This paper presents a possible transceiver architecture meant for integrated solutions while providing tentative block level specifications for the proposed architecture. Existing spectrum sensing techniques are discussed and an integrated low power system architecture at the PHY level suitable for waveform-based spectrum sensing technique that utilizes co-operative spectrum sensing methods is proposed.

Smart utility networks in tv white space

This article presents an overview of the background, technology, regulation, and standardization in the course of deploying smart utility networks (SUNs) in TV white space (TVWS) communications, two wireless technologies currently receiving overwhelming interest in the wireless industry and academia. They are independent to and uncorrelated with each other, but share the same mission: conserving resources and increasing efficiency. This article reviews the systems as separate technologies, and then combines them to propose a hybrid solution that draws out their respective advantages. The first part focuses on SUNs and describes the SUN usage model with typical application requirements and practical examples, followed by the latest developments in standardization initiatives with emphasis on the currently active IEEE 802.15.4g and 802.11ah groups. The second part discusses TVWS, studying and summarizing the regulations governing its usage, and then reports on the standardization bodies' responses to these regulations with a focus on IEEE 802.11af, 802.19.1, and 802.22. Finally, the third part amalgamates the SUN usage model with TVWS regulations and deployment scenarios, providing relationship mapping between the SUN components and regulation-compliant TVWS devices. Further discussions concentrate on the opportunities and challenges along the path of realizing a practical SUN in the TVWS spectrum under the current technical and regulatory conditions. Several recommendations are made from both regulatory and technical standpoints to further increase utilization of SUNs in TVWS.