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Topics in Dynamic Spectrum Access: Market Based Spectrum Sharing and Secondary User Access in Radar Bands
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. (Communicatio System Lab)
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The steady growth in demand for spectrum has increased research interest in dynamic spectrum access schemes. This thesis studies some challenges in dynamic spectrum access based on two strategies: open sharing and hierarchical access. (1) In the open sharing model, the channels are allocated based on an auction process, taking into account the propagation characteristics of the channels, termed as channel heterogeneity. Two distributed dynamic spectrum access schemes are evaluated, sequential and concurrent. We show that the concurrent accessmechanismperforms better in terms of channel utilization and energy consumption, especially in wireless cellular network with an energy constraint. (2) In the hierarchical model, we assess the opportunities for secondary access in the radar band at 5.6GHz. The primary user is a meteorological radar and WLANs are the secondary users. The secondary users implement an interference protection mechanism to protect the radar, such that the WLAN’s transmission is regulated by an interference threshold. We evaluate the aggregate interference caused to the radar from multiple WLANs transmitting. We derive a mathematicalmodel to approximate the probability distribution function of the aggregate interference at the primary user, considering two cases: when secondary users are homogeneously distributed, and when they are heterogeneously distributed. The heterogeneous distribution of secondary users is modeled using an annulus sector with a higher density, called a hot zone. Finally, we evaluate opportunities for secondary access when WLANs employ an interference protection mechanism that considers the radar’s antenna pattern, such that temporal opportunities for transmission exist. The analytical probability distribution function of the interference is verified showing a good agrement with a Monte Carlo simulation. We show that the aggregate interference is sensitive to the propagation environment, thus in the rural case interference is more severe when compared to the urban case. In the evaluation of the hot zonemodel, we observe that the heterogenous distribution of secondary users has impact on the aggregate interference if the hot zone is near to the radar. The mathematical framework presented in this thesis can easily be adapted to assess interference to other types of primary and secondary users.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , xi, 42 p.
Series
Trita-ICT-COS, ISSN 1653-6347 ; 1105
Keyword [en]
spectrum sharing, radar band, cognitive radio
National Category
Telecommunications Information Science
Identifiers
URN: urn:nbn:se:kth:diva-33791OAI: oai:DiVA.org:kth-33791DiVA: diva2:417671
Presentation
2011-06-15, C2-Electrum 1, Isafjordsgatan 26, Kista, 14:00 (English)
Opponent
Supervisors
Note
QC 20110523Available from: 2011-05-23 Created: 2011-05-17 Last updated: 2011-05-23Bibliographically approved
List of papers
1. Distributed spectrum access with energy constraint for heterogeneous channels
Open this publication in new window or tab >>Distributed spectrum access with energy constraint for heterogeneous channels
2010 (English)In: 2010 Proceedings of the 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCom 2010, Cannes, 2010Conference paper (Refereed)
Abstract [en]

The demand for wireless communications services has increased the amount of spectrum resources required, promoting research interest in dynamic spectrum allocation schemes. There exist many promising solutions to allocate spectrum on a dynamic basis in order to get an efficient spectrum usage. One particular form is auction mechanism, tailored for allocating transmission rights on a short term basis to provide efficient allocation of scarce resources. However, most existing approaches are focused on homogeneous settings where all channels are treated as if they have the same propagation characteristics. In this work we consider two distributed auction schemes; sequential and concurrent, based on sequential ascending and combinatorial bidding, respectively, taking into account the propagation conditions of the channels (heterogeneous settings). The performance of these schemes is compared to two reference cases: (i) distributed homogeneous channels allocation (channel-agnostic case), and (ii) the centralized allocation scheme. Experimental results suggest that auction mechanisms which take into account the channel characteristics improve spectrum utilization under energy constraint. For wireless cellular networks with high unit energy cost (low coverage) concurrent access gives a better utilization of the spectrum and energy resources with higher service providers utility.

Place, publisher, year, edition, pages
Cannes: , 2010
Keyword
Auction mechanisms, Channel characteristics, Concurrent access, Distributed Auctions, Dynamic spectrum allocations, Energy constraint, Energy cost, Heterogeneous channels, Propagation characteristics, Scarce resources, Service provider, Short term, Spectrum access, Spectrum usage, Spectrum utilization, Transmission rights, Wireless cellular networks, Wireless communications, Cellular neural networks, Dynamics, Energy resources, Radio, Spectroscopy, Wireless telecommunication systems, Wireless networks
National Category
Other Computer and Information Science
Identifiers
urn:nbn:se:kth:diva-33993 (URN)10.4108/ICST.CROWNCOM2010.9242 (DOI)2-s2.0-77958168642 (ScopusID)9781424458868 (ISBN)
Note

QC 20110523

Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2014-01-16Bibliographically approved
2. Impact of aggregate interference on meteorological radar from secondary users
Open this publication in new window or tab >>Impact of aggregate interference on meteorological radar from secondary users
2011 (English)In: IEEE Wireless Communications and Networking Conference (WCNC), IEEE , 2011, 2167-2172 p.Conference paper (Refereed)
Abstract [en]

In this paper, we investigate the impact of aggregate interference in a secondary spectrum access system. Particularly, meteorological radar operating in 5.6 GHz band is considered to be a primary user. Secondary users are WLAN devices spreading in a large area which induce aggregate interference to the radar. We develop a mathematical model to derive the robability distribution function (PDF) of the aggregate interference. The derivation considers dynamic frequency selection (DFS) mechanism for the protection of the radar such that the transmission of each WLAN is regulated by an interference threshold. Numerical experiments are performed with various propagation environments and densities of WLAN devices. It is observed that the effect of aggregate interference is severe in a rural environment. The interference threshold for individual WLAN should be much lower than the maximum tolerable interference at the radar. Thus, only a limited number of WLANs can transmit at the same time. On the other hand, adverse effect of the aggregate interference is not shown in an urban environment, where up to 10 WLANs per square kilometer can use the radar spectrum without considering the aggregate interference. The framework discussed in this paper can readily be adapted to assess the aggregate interference for other types of radars.

Place, publisher, year, edition, pages
IEEE, 2011
Keyword
aggregate interference, secondary spectrum access, meteorological radar
National Category
Telecommunications Information Science
Identifiers
urn:nbn:se:kth:diva-34000 (URN)10.1109/WCNC.2011.5779468 (DOI)000297160200371 ()2-s2.0-79959322057 (ScopusID)978-1-61284-255-4 (ISBN)
Conference
IEEE Wireless Communications and Networking Conference (WCNC)
Projects
QUASAR
Funder
EU, FP7, Seventh Framework Programme, 248303Wireless@kth
Note

QC 20130403

Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2016-04-27Bibliographically approved
3. Aggregate Interference in Secondary Access with Interference Protection
Open this publication in new window or tab >>Aggregate Interference in Secondary Access with Interference Protection
2011 (English)In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 15, no 6, 629-631 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a derivation of the probability distribution function (pdf) of the aggregate interference in a secondary access network where multiple secondary users cause interference to a single primary user. The derivation considers a practical interference protection mechanism that the transmission of each secondary user is regulated by an interference threshold. Analytic pdf of the interference from a secondary user is obtained. Then, the distribution of the aggregate interference is approximated based on its cumulants. The derived pdf shows a good agreement with Monte Carlo simulation.

Place, publisher, year, edition, pages
IEEE Communications Society, 2011
Keyword
aggregate interference, secondary spectrum access, interference protection
National Category
Telecommunications Information Science
Identifiers
urn:nbn:se:kth:diva-34003 (URN)10.1109/LCOMM.2011.040711.110272 (DOI)000291880700013 ()2-s2.0-79959545656 (ScopusID)
Projects
QUASAR
Funder
EU, FP7, Seventh Framework Programme, 248303Wireless@kth
Note

 QC 20150630. QC 20160128

Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2016-01-28Bibliographically approved
4. Aggregate Interference from Secondary Users with Heterogeneous Density
Open this publication in new window or tab >>Aggregate Interference from Secondary Users with Heterogeneous Density
2011 (English)In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), IEEE , 2011, 428-432 p.Conference paper (Refereed)
Abstract [en]

This paper presents an analytical model to approximate the probability distribution function of the aggregate interference that a primary user receives from multiple secondary transmitters. In particular, we consider heterogeneity in spatial distribution of secondary users such that there are several sites with densely populated secondary users in the whole area. The concentration of secondary users is modeled as an annulus sector with higher user density, which is termed hot zone. The mathematical framework presented in this paper can readily be adapted to various existing interference models. It is observed that the heterogenous user distribution has a considerable impact on the aggregate interference if the hot zone is near the primary receiver, while hot zones over a certain distance is well approximated by a homogeneous secondary user distribution. The aggregate interference also depends on the shape of the hot zone and the interference threshold imposed on the secondary users.

Place, publisher, year, edition, pages
IEEE, 2011
Keyword
aggregate interference, secondary spectrum access, heterogeneous density, hot zone model
National Category
Telecommunications Information Science
Identifiers
urn:nbn:se:kth:diva-34004 (URN)10.1109/PIMRC.2011.6139997 (DOI)000300719700083 ()2-s2.0-84857599763 (ScopusID)978-1-4577-1348-4 (ISBN)
Conference
22nd IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) Location: Toronto, Canada, Date: SEP 11-14, 2011
Projects
QUASAR
Funder
EU, FP7, Seventh Framework Programme, 248303Wireless@kth
Note

QC 20120410

Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2016-04-27Bibliographically approved
5. Temporal secondary access opportuities for WLAN in radar bands
Open this publication in new window or tab >>Temporal secondary access opportuities for WLAN in radar bands
2011 (English)In: Wireless Personal Multimedia Communications (WPMC), 2011 14th International Symposium on, Elsevier, 2011, 6081515- p.Conference paper (Refereed)
Abstract [en]

In this paper we quantify the temporal opportunities for secondary access in radar bands. In our study, WLANs are secondary users homogeneously or heterogeneously distributed, which opportunistically access the radar spectrum. Each WLAN employs dynamic frequency  selection (DFS) as a mechanism to protect the radar from interference. We also consider an interference protection mechanism based on DFS and the prediction of the radar’s antenna pattern, which is termed Temporal DFS. We have the most of the time the probability of accessing the radar band are higher when Temporal DFS is used. As a consequence, there are more active WLANs when Temporal DFS mechanism is considered compare with normal DFS mechanism. This, shows once more that by having knowledge of the primary users activity secondary users can increase the probability of accessing the spectrum and improve spectrum utilization.

Place, publisher, year, edition, pages
Elsevier, 2011
Keyword
aggregate interference, secondary spectrum access, temporal opportunity
National Category
Telecommunications Information Science
Identifiers
urn:nbn:se:kth:diva-34006 (URN)2-s2.0-83655183406 (ScopusID)978-2-908849-26-4 (ISBN)978-1-4577-1786-4 (ISBN)
Conference
2011 14th International Symposium on Wireless Personal Multimedia Communications: Communications, Networking and Applications for the Internet of Things, WPMC'11; Brest; France; 3-7 October 2011
Projects
QUASAR
Funder
EU, FP7, Seventh Framework Programme, 248303Wireless@kth
Note

QC 20140912. QC 20160128

Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2016-01-28Bibliographically approved

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