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Dynamic Cooperative Secondary Access in Hierarchical Spectrum Sharing Networks
Ericsson Corp R&D, Sweden.
KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.ORCID iD: 0000-0002-2764-8099
2014 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 13, no 11, 6068-6080 p.Article in journal (Refereed) Published
Abstract [en]

We address the challenge of energy efficiency in hierarchical spectrum sharing networks with dynamic traffic. We consider a primary and a cognitive secondary transmitter-receiver pair, where the secondary transmitter can utilize cooperative transmission to relay primary traffic while superimposing its own information. The secondary user meets a dilemma in this scenario. By choosing cooperation, it can transmit a packet immediately, but it has to bear the additional cost of relaying. Otherwise, it can wait for the primary user to become idle, which increases the queuing delay that secondary packets experience. To solve this dilemma and trade off delay and energy consumption, we propose dynamic cooperative secondary access control that takes the state of the spectrum sharing network into account. We formulate the problem as a Markov decision process and prove the existence of a stationary policy that is average cost optimal. We evaluate reinforcement learning to find optimal transmission strategy when the traffic and link statistics are not known. We demonstrate that dynamic cooperation is necessary for the secondary system to be able to adapt to changing network conditions and show that optimal sequential decision can significantly improve the tradeoff of the energy consumption and the delay.

Place, publisher, year, edition, pages
2014. Vol. 13, no 11, 6068-6080 p.
Keyword [en]
Hierarchical spectrum sharing, cooperative transmission, queuing systems, Markov decision process, reinforcement learning
National Category
Research subject
URN: urn:nbn:se:kth:diva-122274DOI: 10.1109/TWC.2014.2333744ISI: 000345087700014ScopusID: 2-s2.0-84910116264OAI: diva2:621676
Swedish Research Council

QC 20150115. Updated from manuscript to article in journal.

Available from: 2013-05-16 Created: 2013-05-16 Last updated: 2015-01-15Bibliographically approved
In thesis
1. Cooperative and Cognitive Communication in Wireless Networks
Open this publication in new window or tab >>Cooperative and Cognitive Communication in Wireless Networks
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the last decade, significant efforts and progress have been made by both the industry and academia to meet the rapidly growing demand for wireless applications and services. To achieve more flexible, dynamic and intelligent use of the limited wireless spectrum, cooperative transmission and cognitive networking are proposed as two of the key technologies for the next generation wireless communication systems, such as Long-Term Evolution Advanced. Cooperative transmission techniques, such as cooperative relaying and Multiple-Input and Multiple-Output (MIMO) can increase spectrum efficiency by utilizing the diversity of wireless channels, while cognitive transmitters tune their transmission parameters according to the environment to optimize network level performance. In this thesis, we provide performance modeling and analysis of different cooperative and cognitive communication techniques to exploit their potential.

In the first part of the thesis, we investigate the performance of hop-by-hop cooperative communication on a multihop transmission path applying spatial reuse time division multiplexing, where interference from simultaneous transmissions exists. Based on the models, we compare the performance of hop-by-hop cooperation with the performance of traditional simple multihopping schemes, and give the regimes where hop-by-hop cooperation achieves significant gain. Considering random networks, we propose cooperative geographic routing, the integration of hop-by-hop cooperation with traditional geographic routing, and evaluate the effects of the topology knowledge range and the network density.

In the second part of the thesis, we discuss how cooperative transmission techniques can be utilized in cognitive and hierarchical spectrum sharing networks, where the primary users have transmission guarantees, and the coexisting secondary users need to be cognitive and adjust their transmissions in the shared spectrum bands to conform constraints from the primary users. We consider large-scale coexisting primary and secondary networks, where concurrent primary and secondary transmissions are allowed, and the secondary users provide cooperative relaying for the primary ones and control the interference at the primary receivers by tuning the probability of transmitting and by forming a primary exclusive region around each primary receiver within which all secondary users have to be silent. We define a unified analytic framework to model the performance of cooperative spectrum sharing and cognitive transmission control, characterize their achievable gains, and show that both of the networks have strong incentives to participate in the collaboration.

Finally, we investigate spectrum sharing networks where both primary and secondary users have stochastic packet arrival. Under the constraint that the performance of primary users does not degrade, we find the dilemma for the secondary users. That is, if a secondary user chooses to cooperate, it can transmit immediately even if the primary queue is not empty, but has additional costs for relaying primary packets, such as increased power consumption. We propose a dynamic cooperation scheme for the secondary user so that it can make sequential decision on whether to cooperate or not in each time slot based on the state of the network. We show that optimal sequential decision is necessary to efficiently trade off the cooperation cost and the packet delay of the secondary user.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. vii, 54 p.
TRITA-EE, ISSN 1653-5146 ; 2013:18
National Category
urn:nbn:se:kth:diva-122277 (URN)978-91-7501-731-0 (ISBN)
Public defence
2013-06-05, Q2, Osquldas väg 10, KTH, Stockholm, 10:00 (English)

QC 20130517

Available from: 2013-05-17 Created: 2013-05-16 Last updated: 2014-02-11Bibliographically approved

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