In underlay cognitive radio networks, secondary users can share the spectrum with
primary users as long as the interference caused by the secondary users to primary
users is below a certain predetermined threshold. It is reasonable to assume that
there is always a large pool of secondary users trying to access the channel, which
can be occupied by only one secondary user at a given time. As a result, a multi-user
scheduling problem arises among the secondary users. In this thesis, by manipulating
basic schemes based on selective multi-user diversity, normalized thresholding, transmission power control, and opportunistic round robin, we propose and analyze eight
scheduling schemes of secondary users in an underlay cognitive radio set-up. The system performance of these schemes is quantified by using various performance metrics
such as the average system capacity, normalized average feedback load, scheduling
outage probability, and system fairness of access.
In our proposed schemes, the best user out of all the secondary users in the system
is picked to transmit at each given time slot in order to maximize the average system
capacity. Two thresholds are used in the two rounds of the selection process to
determine the best user. The first threshold is raised by the power constraint from
the primary user. The second threshold, which can be adjusted by us, is introduced
to reduce the feedback load. The overall system performance is therefore dependent
on the choice of these two thresholds and the number of users in the system given
the channel conditions for all the users. In this thesis, by deriving analytical formulas and presenting numerical examples, we try to provide insights of the relationship
between the performance metrics and the involved parameters including two selection
thresholds and the number of active users in the system, in an effort to maximize
the average system capacity as well as satisfy the requirements of scheduling outage
probability and feedback load.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/205811 |
| Date | 12 1900 |
| Creators | Song, Yao |
| Contributors | Alouini, Mohamed-Slim, Computer, Electrical and Mathematical Science and Engineering (CEMSE) Division, Shihada, Basem, Wang, Suojin |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | 2012-12-31, At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2012-12-31. |
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