Underlay and Overlay Transmission in Cognitive Radio
| Autor: | Min Her, 何敏 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In a cognitive radio network system with a collision constraint of primary user, approaches using the overlay, underlay, or the combination of the underlay and overlay methods have been purposed to optimize the transmission of the secondary user. Under the condition that the secondary user knows the general actions but not the exact actions of the primary users, an overlay method was purposed. In this overlay method, both the TV utility distribution (TUD) and the characteristic distribution (CD) of primary users were used to find an optimal frame length with highest throughput. Under the condition that the secondary user has no idea whether the primary user is using the channel or not but knows the exact locations of primary users, an underlay method based on the concept of orbits in astronomy was developed to find the least number of relay and the optimal routing. Under the condition that the secondary user can have the exact actions of the primary user by detecting the leakage power of primary user, an approach utilized both the overlay and underlay method was purposed. By sensing the leakage power of the primary user, the power transmitted by secondary user was adjusted to maximize the SNR and the capacity of the secondary user. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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