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Secondary spectrum access in TV-bands with combined co-channel and adjacent channel interference constraints
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.
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.ORCID iD: 0000-0001-7642-3067
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.ORCID iD: 0000-0003-4986-6123
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.

Place, publisher, year, edition, pages
2012. 452-460 p.
Keyword [en]
TV White Space, secondary spectrum reuse, optimization, aggregate interference, adjacent channel interference, geo-location database
National Category
Communication Systems
Identifiers
URN: urn:nbn:se:kth:diva-104565DOI: 10.1109/DYSPAN.2012.6478169ISI: 000320661800060Scopus ID: 2-s2.0-84876026432ISBN: 978-1-4673-4448-7 (print)OAI: oai:DiVA.org:kth-104565DiVA: diva2:565065
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
In thesis
1. Availability Assessment for Secondary Access in TV White Space
Open this publication in new window or tab >>Availability Assessment for Secondary Access in TV White Space
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:nbn:se:kth:diva-104420 (URN)
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
2. Efficient Spectrum Utilization of Uhf Broadcast Band
Open this publication in new window or tab >>Efficient Spectrum Utilization of Uhf Broadcast Band
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The UHF band between 470-790 MHz, currently occupied by digital ter- restrial TV (DTT) distribution in Europe, is widely regarded as a premium spectrum band for providing mobile coverage. With the exponential increase in wireless data traffic in recent years, there has been growing interests in gaining access to this spectrum band for wireless broadband services. The secondary access in TV White Space is considered as one cost-effective way to reuse the spectrum unoccupied by the primary DTT network. On the other hand, the declining influence of DTT and the converging trends of video con- sumption on TV and mobile platforms are new incentives for the regulator to reconsider the optimal utilization of the UHF broadcast band. The proposal to re-farm the UHF band for a converged content distribution network was born under theses circumstances.

This thesis intends to develop a methodology for evaluating the technical performance of these options for utilizing UHF broadcast band and quantify- ing their gains in terms of achievable extra capacity and spectrum savings. For the secondary access in TV white space, our study indicates a considerable po- tential for low power secondary, which is mostly limited by the adjacent chan- nel interference generated from the densely deployed secondary devices due to the cumulative effect of multichannel interference. On the other hand, this potential does not translate directly into capacity for a WiFi-like secondary system based on CSMA/CA protocol, as the network congestion and self- interference within the secondary system has a greater impact on the network throughput than the primary interference constraint.

Our study on the cellular content distribution network reveals more po- tential benefits for re-farming the UHF broadcast band and reallocating it for a converged platform. This platform is based on cellular infrastructure and can provide TV service with the same level of quality requirement as DTT by delivering the video content via either broadcast or unicast as the situa- tion dictates. We have developed a resource manage framework to minimize its spectrum requirement for providing TV service and identified a significant amount of spectrum that can be reused by the converged platform to provide extra mobile broadband capacity in urban and sparsely populated rural areas.

Overall, we have arrived at the conclusion that the concept of cellular con- tent distribution in a re-farmed UHF band shows a more promising prospect than the secondary access in TV white space in the long run. Nevertheless, low power secondary is still considered as a flexible and low-cost way to exploit the underutilized spectrum in the short term, despite its uncertainty in future availability. On the other hand, the re-farming of UHF broadcast band is a long and difficult regulation process with substantial opposition from the in- cumbent.The results from this study could serve as input for future regulatory decisions on the UHF band allocation and cost-benefit analysis for deploying new systems to access this spectrum band. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 157 p.
Series
TRITA-ICT-COS, ISSN 1653-6347 ; 1406
Keyword
TV White Space, CellTV, UHF Band, Spectrum
National Category
Telecommunications
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-146078 (URN)
Public defence
2014-06-12, Sal E, Forum, Kungliga Tekniska Högskolan, Isafjordsgatan 26, Kista, Stockholm, 14:00 (English)
Opponent
Supervisors
Projects
EU FP7 QUASAREU FP7 METIS
Note

QC 20140609

Available from: 2014-06-09 Created: 2014-06-05 Last updated: 2014-06-10Bibliographically approved

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