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Performance analysis of relay-assisted cognitive radio systems with superposition coding
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
2012 (English)In: Proceedings of the IEEE 23rd International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE , 2012, 1226-1231 p.Conference paper (Refereed)
Abstract [en]

We study the problem of relay selection in a cooperative cognitive radio system in which a secondary transmitter can act as a relay for the primary transmitter in order to maximize the primary user's gain. Moreover, we take into account that the secondary users may have certain quality-of-service (QoS) requirements which need to be satisfied. In the cooperative scenario of a cognitive radio system, the primary user should have an incentive to allow the secondary user to transmit in its licensed band. At the same time, the secondary user should be able to transmit its own data with the required QoS in order to be willing to help the primary user's performance by relaying its data. Hence, we take into account both primary and secondary users' objectives. We use numerical methods in order to study how different parameters, such as assigned powers in the coding scheme, direct link reliability, and the number of secondary users affect the overall system performance. Our results show that the gain, which the primary user can achieve by cooperation, highly depends on the quality of its direct link as well as the secondary users' QoS requirements. Furthermore, the percentage of cooperation instances between secondary users and the primary user is dependent on the amount of power the secondary users allocate for relaying the primary's signal based on the direct link quality.

Place, publisher, year, edition, pages
IEEE , 2012. 1226-1231 p.
, IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, ISSN 2166-9570
Keyword [en]
Coding scheme, Cooperative scenarios, Direct links, ITS data, Performance analysis, QoS requirements, Relay selection, Super-position coding
National Category
Communication Systems
Research subject
URN: urn:nbn:se:kth:diva-98778DOI: 10.1109/PIMRC.2012.6362533ISI: 000312809400208ScopusID: 2-s2.0-84871965529ISBN: 978-146732569-1OAI: diva2:538961
IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Sydney, NSW
ICT - The Next Generation

QC 20130116

Available from: 2012-07-02 Created: 2012-07-02 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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Shalmashi, ServehSlimane, Ben
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