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Innovative Approaches to Spectrum Selection, Sensing, and Sharing in Cognitive Radio Networks

Ghosh, Chittabrata
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242943376

Abstract Details

2009, PhD, University of Cincinnati, Engineering : Computer Science and Engineering.
In a cognitive radio network (CRN), bands of a spectrum are shared by licensed (primary) and unlicensed (secondary) users in that preferential order. It is generally recognized that the spectral occupancy by primary users exhibit dynamical spatial and temporal properties. In the open literature, there exist no accurate time-varying model representing the spectrum occupancy that the wireless researchers could employ for evaluating new algorithms and techniques designed for dynamic spectrum access (DSA). We use statistical characteristics from actual radio frequency measurements, obtain first- and second-order parameters, and define a statistical spectrum occupancy model based on a combination of several different probability density functions (PDFs). One of the fundamental issues in analyzing spectrum occupancy is to characterize it in terms of probabilities and study probabilistic distributions over the spectrum. To reduce computational complexity of the exact distribution of total number of free bands, we resort to efficient approximation techniques. Furthermore, we characterize free bands into five different types based on the occupancy of its adjacent bands. The probability distribution of total number of each type of bands is therefore determined. Two corresponding algorithms are effectively developed to compute the distributions, and our extensive simulation results show the effectiveness of the proposed analytical model. Design of an efficient spectrum sensing scheme is a challenging task, especially when false alarms and misdetections are present. The status of the band is to be monitored over a number of consecutive time periods, with each time period being of a specific time interval. The status of the sub-band at any time point is either free or busy. We proved that the status of the band over time evolves randomly, following a Markov chain. The cognitive radio assesses the band, whether or not it is free, and the assessment is prone to errors. The errors are modeled probabilistically and the entire edifice is brought under a hidden Markov chain model in predicting the true status of the band. After spectrum sensing, our research direction is on spectrum sharing using cooperative communication. We discuss allocation strategies of unused bands among the cognitive users. We introduce a cooperative N-person Game among the N cognitive users in a CRN and then identify strategies that help achieve Nash equilibrium. When licensed users arrive in any of those sub-bands involved in unlicensed user communication, the affected cognitive users in those bands remove them out of the N-person game and assess their optional strategies with the licensed users using the 2-person game approach for coexistence with the licensed users. In the sequel of spectrum sharing, we present three novel priority-based spectrum allocation techniques for enabling dynamic spectrum access (DSA) networks employing non-contiguous orthogonal frequency division multiplexing (NC-OFDM) transmission. The allocation of bandwidth to unlicensed users, without significantly increasing the interference on the existing licensed users, is a challenge for Ultra Wideband (UWB) networks. We propose a novel Rake Optimization and Power Aware Scheduling (ROPAS) architecture for UWB networks as multipath diversity in UWB communication encourages us to use a Rake receiver.
Dharma Agrawal (Advisor)
Raj Bhatnagar (Committee Member)
Chia-Yung Han (Committee Member)
Yiming Hu (Committee Member)
Marepalli Rao (Committee Member)
211 p.
Computer Science
Cognitive Radio; Software Defined Radio; Spectrum Sensing; Spectrum Sharing; Game Theory; Hidden Markov Models

Recommended Citations

Citations

  • Ghosh, C. (2009). Innovative Approaches to Spectrum Selection, Sensing, and Sharing in Cognitive Radio Networks [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242943376

    APA Style (7th edition)

  • Ghosh, Chittabrata. Innovative Approaches to Spectrum Selection, Sensing, and Sharing in Cognitive Radio Networks. 2009. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242943376.

    MLA Style (8th edition)

  • Ghosh, Chittabrata. "Innovative Approaches to Spectrum Selection, Sensing, and Sharing in Cognitive Radio Networks." Doctoral dissertation, University of Cincinnati, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242943376

    Chicago Manual of Style (17th edition)

ucin1242943376
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© 2009, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.