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Availability Assessment for Secondary Access in TV White Space
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. (Radio System)
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, the rapid growth in wireless data traffic has posed not only unique opportunities but also great challenges for the wireless industry. In order to meet the growing demand without excessive cost or energy consumption, one feasible option for the operators is to acquire more spectrum for wireless communication. Unlike the lengthy allocation process for exclusive spectrum licenses, secondary spectrum access is deemed as a flexible alternative to obtain additional spectrum at low cost. In particular, the VHF/UHF TV band, so called ’TV White Space’, is considered as the most promising candidate for secondary access thanks to its well defined primary usage and favorable propagation characteristic for building penetration and wide area coverage.

Therefore, secondary access in the TV band has been extensively studied by both academic and industry. Most of the research have focused on the detection of ’spectrum holes’ with sensing technologies, while a few others have provided high level analysis of the potential of TV white space with simplistic secondary interference model for single secondary user. Only A limited number of studies have investigated aggregate interference from multiple secondary users, but even these studies have ignored the adjacent channel interference from secondary users close to the TV receivers.

Thus, in this thesis we first concentrate on examining the effect of harmful interference on TV reception from short range devices transmitting on adjacent channels, and model the accumulative effect of multi-channel interferences observed in the measurement. Then the basic methodology for evaluating the potential of TV white space is developed in the second part of the thesis, where we propose a new analytical approach for regulating the secondary transmit power that significantly outperforms the existing method in the regulatory framework. Finally, we combine the aggregate interference model and the basic regulation methodology to extend the analysis from single user to multiple user case, first with only users transmitting on different adjacent TV channels and later also including users transmitting on co-channels.

Our performance evaluation have shown that the effect of adjacent channel interference at close distance is far from negligible and the accumulative effect of multi-channel interferences has substantial impact on the scalability of a secondary system. In fact, the adjacent channel interference proves to be the primary limiting factor of the TV white space availability for low power short range systems. Nonetheless, because the proposed approach can adapt to varying environmental conditions and consequently utilize the spectrum reuse opportunity more efficiently than existing frameworks, we can still note considerable amount of TV white space available for short range secondary devices.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , vii, 37 p.
Series
Trita-ICT-COS, ISSN 1653-6347 ; 1210
National Category
Telecommunications Communication Systems
Identifiers
URN: urn:nbn:se:kth:diva-104420OAI: oai:DiVA.org:kth-104420DiVA: diva2:564515
Presentation
2012-11-09, Sal/Hall C2, Electrum, Isafjordsgatan 26, Kista, 13:00 (English)
Opponent
Supervisors
Projects
QUASAR
Funder
ICT - The Next GenerationEU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20121106

Available from: 2012-11-06 Created: 2012-11-01 Last updated: 2013-11-27Bibliographically approved
List of papers
1. Experimental Verification of Indoor TV White Space Opportunity Prediction Model
Open this publication in new window or tab >>Experimental Verification of Indoor TV White Space Opportunity Prediction Model
2010 (English)In: 2010 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCom 2010, 2010Conference paper, Published paper (Refereed)
Abstract [en]

Recent work has demonstrated that the underutilized spectrum in the Digital Television Bands, commonly referred to as TV White Space (TVWS), is a prime candidate for opportunistic spectrum access (OSA). However, a systematic assessment of the availability of this spectrum for secondary transmission was, until very recently, lacking. In a TVWS opportunity prediction model to estimate indoor secondary usage probability was proposed. In this paper we aim at verifying this model by means of measurement campaigns in both laboratory and real indoor environments. The match between the predictions from the simulation models in and measurement results suggest that the model provides a realistic evaluation of the opportunities in TVWS for low power indoor secondary usage.

Keyword
white space, digital television broadcasting, opportunistic spectrum access
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-48305 (URN)10.4108/ICST.CROWNCOM2010.9286 (DOI)2-s2.0-77958168179 (Scopus ID)978-1-4244-5885-1 (ISBN)
Conference
2010 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCom 2010. Cannes, France 9 June 2010 - 11 June 2010
Projects
QUASAR
Funder
Wireless@kthEU, FP7, Seventh Framework Programme
Note

QC 20150710

Available from: 2011-11-17 Created: 2011-11-17 Last updated: 2015-07-10Bibliographically approved
2. A model for Aggregate Adjacent Channel Interference in TV White Space
Open this publication in new window or tab >>A model for Aggregate Adjacent Channel Interference in TV White Space
2011 (English)In: IEEE Vehicular Technology Conference, 2011, 1-5 p.Conference paper, Published paper (Refereed)
Abstract [en]

The presence of white spaces and spectrum holes in the TV bands represents potential opportunities for alleviating the apparent spectrum scarcity. Opportunistic spectrum access (OSA) has been proposed for the secondary user's operation and the main concern is the harmful interference that secondary systems could cause to the primary receivers. Existing studies have focused on establishing the limits for co-channel and adjacent channel interference when only one adjacent channel is used by a single secondary user. This paper presents a characterization of the aggregate adjacent channel interference (AACI) when different adjacent channels are simultaneously accessed by multiple secondary users or white space devices (WSDs). An analytical expression is proposed to approximate the limits of the tolerable AACI. Our model states that not only the interference received in each adjacent channel should stay below the corresponding threshold for that particular channel, but also the weighted sum of the total adjacent channel interference power should be kept below a certain threshold. Measurement campaigns show the cumulative effect of the adjacent channel interference (ACI) when multiple WSDs access multiple adjacent channels at the same time. The proposed analytical expression for AACI closely matches the measurement results.

Series
IEEE Vehicular Technology Conference, ISSN 1550-2252
Keyword
white space, opportunistic spectrum access, adjacent channel interference, measurements
National Category
Telecommunications
Research subject
SRA - ICT
Identifiers
urn:nbn:se:kth:diva-48302 (URN)10.1109/VETECS.2011.5956237 (DOI)000295405800122 ()2-s2.0-80051981578 (Scopus ID)978-1-4244-8332-7 (ISBN)
Conference
2011 IEEE 73rd Vehicular Technology Conference, VTC2011-Spring. Budapest, Hungary, 15 May 2011 - 18 May 2011
Projects
QUASAR
Funder
EU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20150706

Available from: 2011-11-17 Created: 2011-11-17 Last updated: 2015-07-06Bibliographically approved
3. On the Permissible Transmit Power for Secondary User in TV White Spaces
Open this publication in new window or tab >>On the Permissible Transmit Power for Secondary User in TV White Spaces
2012 (English)In: 2012 7th International Conference on Cognitive Radio Oriented Wireless Networks (CROWNCOM), IEEE , 2012, 13-17 p.Conference paper, Published paper (Refereed)
Abstract [en]

Secondary spectrum access to TV white spaces is considered as a promising solution to relieve the spectrum shortage. In Europe, SE43 working group in CEPT is leading the discussion on the technical requirements for exploiting TV white spaces through the recent ECC report 159. Its analytical approach for determining the maximum permissible power for the secondary user, however, overestimates the power level, and leads to significant violation of the interference limit for TV reception. In this letter, we address the problem by proposing a new approach for determining the secondary user transmit power based on the framework established in ECC report 159. Monte Carlo simulation shows that our method keeps the interference close to the target.

Place, publisher, year, edition, pages
IEEE, 2012
Keyword
Terms—TV white space, ECC Report 159, interference protection, transmit power, shadow fading
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-104563 (URN)10.4108/icst.crowncom.2012.248437 (DOI)000310377900003 ()2-s2.0-84869471031 (Scopus ID)978-1-936968-55-8 (ISBN)
Conference
2012 7th International ICST Conference on Cognitive Radio Oriented Wireless Ntworks and Communications, CROWNCOM 2012; Stockholm;18 June 2012 through 20 June 2012
Projects
QUASAR
Funder
ICT - The Next GenerationWireless@kth
Note

QC 20121106

Available from: 2012-11-06 Created: 2012-11-06 Last updated: 2014-06-10Bibliographically approved
4. Controlling Aggregate Interference under Adjacent Channel Interference Constraint in TV White Space
Open this publication in new window or tab >>Controlling Aggregate Interference under Adjacent Channel Interference Constraint in TV White Space
2012 (English)In: 2012 7th International Conference on Cognitive Radio Oriented Wireless Networks (CROWNCOM), IEEE , 2012, 1-6 p.Conference paper, Published paper (Refereed)
Abstract [en]

TV White space, where secondary systems can be deployed inside the TV coverage area and utilize the geographically unoccupied TV channels, is considered as a promising solution to relieve the spectrum shortage. To utilize this spectrum, the secondary users must ensure the protection of TV receptionfrom harmful interference on both co-channel and adjacent channels. In this paper, we propose an analytical approach to determining the permissible transmit power for short-range secondary users under aggregate adjacent channel interferenceconstraint in TV white space. This approach employs statistical interference modeling which considers random deployment of secondary users, antenna gain pattern, shadow fading, and the cumulative effect of interference from multiple adjacent channels. Numerical results show that the proposed scheme permits significantly higher transmit power than the existing deterministic method does, while at the same time, it keeps the required level of TV protection. Therefore, considerable potential for the shortrange secondary access to TV white space is expected with our approach.

Place, publisher, year, edition, pages
IEEE, 2012
Keyword
TV White Space, aggregate interference, transmit power, adjacent channel, geo-location database
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-104564 (URN)10.4108/icst.crowncom.2012.248439 (DOI)000310377900001 ()2-s2.0-84869459967 (Scopus ID)978-1-936968-55-8 (ISBN)
Conference
2012 7th International ICST Conference on Cognitive Radio Oriented Wireless Ntworks and Communications, CROWNCOM 2012; Stockholm; 18 June 2012 through 20 June 2012
Projects
QUASAR
Funder
ICT - The Next GenerationWireless@kthEU, FP7, Seventh Framework Programme
Note

QC 20121106

Available from: 2012-11-06 Created: 2012-11-06 Last updated: 2014-06-09Bibliographically approved
5. Secondary spectrum access in TV-bands with combined co-channel and adjacent channel interference constraints
Open this publication in new window or tab >>Secondary spectrum access in TV-bands with combined co-channel and adjacent channel interference constraints
2012 (English)In: 2012 IEEE International Symposium on Dynamic Spectrum Access Networks, DYSPAN 2012, 2012, 452-460 p.Conference paper, Published paper (Refereed)
Abstract [en]

The potential of VHF/UHF band as a candidate for secondary spectrum access, so called ”TV white spaces”, has been intensively investigated in recent years. However, the impact of the accumulated interference from multiple secondary users on different adjacent channels has not been well studied thus far, let alone the effect of combined interference from both co-channel and adjacent channels. This paper presents a framework for assessing secondary spectrum reuse opportunities for portable and mobile devices that comply with geo-location database concepts. The opportunity is evaluated in terms of the maximal number of secondary users that can access the ”TV white space” simultaneously. Particular emphasis is given to the protection of TV receiver from harmful aggregate interference originated from not only the secondary users outside the TV coverage on the same channel but also those close to the TV receivers operating on different adjacent TV channels. An optimization problem is solved to maximize the number of secondary users admitted to the available TV channels at different locations. Through in-depth analysis of the interference characteristics of the optimal solution, it is identified that the cumulative effect of adjacent channel interferences has the dominant impact on TV reception, particularly for the case of secondary devices with limited transmit power. This suggests the possibility to achieve near-optimal exploitation of TV-bands for secondary reuse without explicit coordination of co-channel interference from the secondary users deployed over a wide geographical area.

Keyword
TV White Space, secondary spectrum reuse, optimization, aggregate interference, adjacent channel interference, geo-location database
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-104565 (URN)10.1109/DYSPAN.2012.6478169 (DOI)000320661800060 ()2-s2.0-84876026432 (Scopus ID)978-1-4673-4448-7 (ISBN)
Conference
2012 IEEE International Symposium on Dynamic Spectrum Access Networks, DYSPAN 2012; Bellevue, WA; United States; 16 October 2012 through 19 October 2012
Projects
QUASAR
Funder
ICT - The Next GenerationWireless@kthEU, FP7, Seventh Framework Programme
Note

QC 20121106

Available from: 2012-11-06 Created: 2012-11-06 Last updated: 2014-06-09Bibliographically approved

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