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Competition in Private Commons: Price War or Market Sharing?
"... Abstract—This paper characterizes the outcomes of secondary spectrum markets when multiple providers compete for sec-ondary demand. We study a competition model in which each provider aims to enhance its revenue by opportunistically serv-ing a price dependent secondary demand, while also serving ded ..."
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Abstract—This paper characterizes the outcomes of secondary spectrum markets when multiple providers compete for sec-ondary demand. We study a competition model in which each provider aims to enhance its revenue by opportunistically serv-ing a price dependent secondary demand, while also serving dedicated primary demand. We consider two methodologies for sharing spectrum between primary and secondary demand: In coordinated access, spectrum providers have the option to decline a secondary access request if that helps enhance their revenue. We explicitly characterize a break-even price such that profitability of secondary access provision is guaranteed if secondary access is priced above the break-even price, regardless of the volume of secondary demand. Consequently, we establish that competition among providers that employ optimal coordinated access leads to a price war, as a result of which the provider with the lowest break-even price captures the entire market. This result holds for arbitrary secondary demand functions. In uncoordinated access, primary and secondary users share spectrum on equal basis, akin to ISM bands. Under this policy, we characterize a market sharing price which determines a provider’s willingness to share the market. We show an instance where the market sharing price is strictly greater than the break-even price, indicating that market equilibrium in an uncoordinated access setting can be fundamentally different as it opens up the possibility of providers sharing the market at higher prices. I.
Network Dimensioning with Carrier Aggregation
"... Abstract—A recent policy ruling by the Federal Com-munications Commission (FCC) set aside a fixed amount of cleared spectrum for smaller network providers. Thanks to this ruling, smaller providers can improve their quality of service using carrier aggregation. In this paper, we determine the optimal ..."
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Abstract—A recent policy ruling by the Federal Com-munications Commission (FCC) set aside a fixed amount of cleared spectrum for smaller network providers. Thanks to this ruling, smaller providers can improve their quality of service using carrier aggregation. In this paper, we determine the optimal (minimum) level of carrier aggre-gation that a smaller provider needs in order to bring its service in line with a larger provider in the same market. Toward this end, we provide an asymptotically exact formula for the loss (blocking) probability of flows under a quality-driven (QD) regime. Using this formula, we establish an efficient way of numerically calculating the optimal level of carrier aggregation and derive scaling laws. Specifically, we show that the optimal level of carrier aggregation scales sub-linearly with respect to the scaling factor, i.e., the ratio between the network capacities of the two providers, and decreases with the initial traffic load of the providers. We derive a closed-form linear upper bound on the optimal level of carrier aggregation and prove that it is the tightest possible. We provide numerical results, showing the accuracy of our methods and illustrating their use. We also discuss the extension of our results to delay-related metrics as well as their application to profitable pricing in secondary spectrum markets. I.
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"... Dynamic spectrum access (DSA) paves a new way to solve the spectrum-scarcity problem caused by conventional command-and-control spectrum allocation. DSA enhances the efficien- ..."
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Dynamic spectrum access (DSA) paves a new way to solve the spectrum-scarcity problem caused by conventional command-and-control spectrum allocation. DSA enhances the efficien-
Time-Frequency Spectrum Leasing for OFDM-Based Dynamic Spectrum Sharing Systems
"... Abstract—In cognitive radio systems, Dynamic Spectrum Leas-ing (DSL) can improve the efficiency of spectrum utilization. In DSL, the primary user who has the license for a part of the bandwidth, decides to lease it to a secondary user or not. In this paper, we assume an OFDM-based system and perform ..."
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Abstract—In cognitive radio systems, Dynamic Spectrum Leas-ing (DSL) can improve the efficiency of spectrum utilization. In DSL, the primary user who has the license for a part of the bandwidth, decides to lease it to a secondary user or not. In this paper, we assume an OFDM-based system and perform the leasing operation in this system where the primary user leases the spectrum for a number of OFDM symbols to secondary users in exchange of a better quality-of-service achieved by secondary network cooperation. The secondary users use a part of the spectrum for relaying the primary data to the primary receiver and the rest of the spectrum for their own transmissions. More precisely, we propose a time-frequency domain leasing scheme. Simulation results show that both primary and secondary users benefit from this proposed spectrum sharing strategy. I.
Coexistence of Wireless Networks for Shared Spectrum Access
, 2014
"... The radio frequency spectrum is not being efficiently utilized partly due to the current policy of allocating the frequency bands to specific services and users. In opportunistic spectrum access (OSA), the “white spaces ” that are not occupied by primary users (a.k.a. incumbent users) can be opportu ..."
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The radio frequency spectrum is not being efficiently utilized partly due to the current policy of allocating the frequency bands to specific services and users. In opportunistic spectrum access (OSA), the “white spaces ” that are not occupied by primary users (a.k.a. incumbent users) can be opportunistically utilized by secondary users. To achieve this, we need to solve two problems: (i) primary-secondary incumbent protection, i.e., prevention of harmful interference from secondary users to primary users; (ii) secondary-secondary network coexistence, i.e., mitigation of mutual interference among secondary users. The first problem has been addressed by spectrum sensing techniques in cognitive radio (CR) networks and geolocation database services in database-driven spectrum sharing. The second problem is the main focus of this dissertation. To obtain a clear picture of coexistence issues, we propose a taxonomy of heterogeneous coexistence mechanisms for shared spectrum access. Based on the taxonomy, we choose to focus on four typical coexistence scenarios in this dissertation. Firstly, we study sensing-based OSA, when secondary users are capable of employing the channel aggregation technique. However, channel aggregation is not always beneficial due to dynamic spectrum availability and limited radio capability. We propose a channel usage
Efficient Identification and Utilization of Spectrum Opportunities in Cognitive Radio Networks
, 2010
"... To my wife Hee Sun, and my parents ii ACKNOWLEDGEMENTS I would like to express my sincere gratitude to Professor Kang G. Shin for his extraordinary support and guidance during my doctoral studies. He has inspired me with many critical aspects of becoming a good researcher such as completeness, imagi ..."
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To my wife Hee Sun, and my parents ii ACKNOWLEDGEMENTS I would like to express my sincere gratitude to Professor Kang G. Shin for his extraordinary support and guidance during my doctoral studies. He has inspired me with many critical aspects of becoming a good researcher such as completeness, imagination, practicality, and agility. He has advised me not only on my research, but also on my career and life. I thus feel fortunate to work with him and proud of being a member of his research group, Real-Time Computing Laboratory. I am also thankful to my research committee, Professor Mingyan Liu, Professor Achil-leas Anastasopoulos, and Professor Jason N. Flinn for their support and valuable suggestions on my dissertation. My special thanks go to my beloved wife, Hee Sun Min, and my parents. Hee Sun has been my biggest supporter during my doctoral studies enduring hard times together. I am indebted to my parents for their unconditional love and support throughout my life. It would not have been possible to stand where I am now without them. I feel grateful to Professor Mingyan Liu, Dr. Carlos Cordeiro, Dr. Chun-Ting Chou, and Professor Demosthenis Teneketzis for serving as my reference. I also thank my mentors and collaborators, Dr. Bong-Jun Ko at IBM T.J. Watson Research
Approved by First Reader
, 2012
"... This dissertation would have never been possible without my advisor, Professor Iordanis Koutsopoulos. I am deeply grateful for his patience and the concern he has shown for my academic and personal improvement. He supported me when I was disappointed, sometimes even ready to quit, and he encouraged ..."
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This dissertation would have never been possible without my advisor, Professor Iordanis Koutsopoulos. I am deeply grateful for his patience and the concern he has shown for my academic and personal improvement. He supported me when I was disappointed, sometimes even ready to quit, and he encouraged me to further improve my research results when I was too optimistic and believed that they were good enough. His passion for top quality work changed my way of thinking not only about research but also about many aspects of my life. Now I can see it clearly: His tutelage was a perfectly orchestrated combination of close guidance and academic freedom to pursue the research problems that attracted me, with the methods I preferred. Iordanis, thank you. I will never forget this. During my studies I had the great opportunity to work and more importantly to meet and discuss with very interesting people, experts in their fields. First of all, I would like to thank Professor Leandros Tassiulas for giving me the opportunity to be a member of his research team and participate in many interesting European Union and National research projects. This experience broadened my research view and played a key role in the completion of my PhD.
