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On Secondary User Transmission Schemes in Relay-Assisted Cognitive Radio Networks
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).ORCID iD: 0000-0002-2370-4567
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.ORCID iD: 0000-0001-9697-9978
2013 (English)In: 2013 IEEE 77th Vehicular Technology Conference (VTC Spring), IEEE , 2013, 6692665- p.Conference paper (Refereed)
Abstract [en]

We consider a cooperative cognitive radio network with one primary user and many secondary users. In each transmission frame, one secondary user is selected to act as a relay for the primary user and also transmits its own data. Three different schemes for the secondary user's transmission is studied, namely, time-splitting, superposition coding, and a combined scheme that takes advantages of both time-splitting and superposition coding schemes. We formulate the relay selection problem for each scheme with the objective of maximizing the secondary user's data rate while satisfying a pre-defined gain threshold for the primary user. This constraint provides an incentive for the primary user when allowing the secondary user access its licensed band. We obtain the optimal solution for this problem in each scheme, on which the relay selection is based on. Finally, we compare the performance of different schemes using Monte-Carlo simulations.

Place, publisher, year, edition, pages
IEEE , 2013. 6692665- p.
, IEEE Vehicular Technology Conference Proceedings, ISSN 1550-2252
Keyword [en]
Cognitive radio network, Combined schemes, Cooperative Cognitive Radio Networks, Monte-Carlo simulations, Optimal solutions, Super-position coding, Transmission frames, Transmission schemes
National Category
Communication Systems
URN: urn:nbn:se:kth:diva-116589DOI: 10.1109/VTCSpring.2013.6692665ISI: 000331081500288ScopusID: 2-s2.0-84893523068ISBN: 978-1-4673-6337-2OAI: diva2:596201
2013 IEEE 77th Vehicular Technology Conference, VTC Spring 2013; Dresden; Germany; 2 June 2013 through 5 June 2013
Mobile and wireless communications Enablers for Twenty-twenty (2020) Information Society (METIS)
EU, FP7, Seventh Framework Programme

QC 20140312

Available from: 2013-01-21 Created: 2013-01-21 Last updated: 2014-05-09Bibliographically approved
In thesis
1. Cooperative Spectrum Sharing and Device-to-Device Communications
Open this publication in new window or tab >>Cooperative Spectrum Sharing and Device-to-Device Communications
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The steep growth in the mobile data traffic has gained a lot of attention in recent years. This growth is mainly the result of emerging applications, multimedia services, and revolutions in the device technology. With current deployments and radio resources, operators will not be able to cope with the growing demands. Consequently, there is a need to either provide new resources or increase the efficiency of what is available. Proposed solutions for accommodating growing data traffic are based on improvements in three dimensions: efficient use of radio resources especially the spectrum, technology advancements, and densifying the current infrastructure. In this thesis, we focus on the spectrum dimension. Providing more spectrum is a long-term process. However, increasing the spectrum usage and efficiency can be put rapidly in practice. We discuss potential solutions in the area of spectrum sharing. Among enabling technologies to facilitate spectrum sharing, we consider the cognitive radio and device-to-device (D2D) communications.

In order to gain from sharing the spectrum, systems need to somehow deal with extra sources of interference. In the first part of the thesis, we consider a primary-secondary sharing model in cognitive radio networks. We employ the cooperative communication method in order to facilitate the access of the secondary system to the licensed spectrum of the primary system, and therefore increase the spectrum usage. The cooperation between the two systems is formed provided that it is beneficial for the primary system. In this way, the primary users' quality-of-service can be preserved while at the same time the secondary users can access the spectrum. This cooperative approach prevents both systems from concurrent transmissions. As a consequence, the need for interference control techniques are eliminated. We evaluate different models and transmission schemes and optimize the corresponding parameters to quantify the gain resulting from cooperative spectrum sharing.

In the second part of the thesis, we consider spectrum sharing within one system between different types of users. This is done in the context of D2D communications where close proximity users can transmit directly to each other. For this type of communications, either dedicated resources are allocated or resources of the cellular users are reused. We first study the feasibility of cooperation between D2D and cellular users and identify the scenarios where it can be beneficial. Then we take on a challenging problem which guarantees the gain from the D2D communication, namely the mode selection. For this problem, we characterize the decision criteria that determines if D2D communication is gainful. Next, we focus on the problem of interference in D2D communications underlaying cellular networks, where the same spectrum is reused in the spatial domain. In such scenarios, the potential gain is determined by how the interference is managed, which in turn depends on the amount of available information at the base station. The more information is required, the more signaling is needed. In this part of the thesis, we address the trade-off between the signaling overhead and the performance of the system and propose a novel approach for interference control which requires very little information on the D2D users.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 49 p.
TRITA-ICT-COS, ISSN 1653-6347 ; 1405
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Communication Systems Telecommunications
urn:nbn:se:kth:diva-145013 (URN)
2014-06-02, sal D, Forum, KTH-ICT, Isafjordsgatan 39, Kista, 13:00 (English)

QC 20140509

Available from: 2014-05-09 Created: 2014-05-05 Last updated: 2014-05-16Bibliographically approved

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