Ma_Yingying.pdf (1.32 MB)
Optimal Spectrum Sensing in Cognitive Radio Networks and Utility Optimization in Wireless Sensor Networks
thesis
posted on 2016-06-21, 00:00 authored by Yingying MaIn cognitive radio networks, spectrum sensing is the most significant
element to detect the spectrum occupied by the primary users. The
objective of our work is to jointly detect multibands with
non-cooperative spectrum sensing and cooperative spectrum sensing. We
are going to maximize the aggregate throughput of the secondary users
over multiple bands, and simultaneously to limit the interference
imposed to the primary users. Energy detection is applied to our study,
which requires little prior information of the primary users. Designing
appropriate thresholds of the energy detectors is critical to determine
the performance of detection. The problem is formulated as a nonconvex
optimization problem, which is intractable to solve, due to the high
computational complexity. In this dissertation, we use the Taguchi
method to estimate the gradient of the aggregate throughput function,
and then determine the thresholds of the energy detectors and linear
combination weights of the linear fusion rule. In noncooperative
spectrum sensing, the cost function is defined as the aggregate
throughput with thresholds of energy detectors as parameters. Multiple
secondary user cooperative spectrum sensing is a more sophisticated case
where the parameters of the thresholds and linear weights need
optimization. In both noncooperative spectrum sensing and cooperative
spectrum sensing, the Taguchi method is employed to find the optimal
solution. One of the advantages of our approach is to optimize the
thresholds and the linear weights simultaneously by solving the problem
where the changing weights result in different limit ranges for the
thresholds. The duration of sensing is another factor which affects the
aggregate throughput. There exists a tradeoff that longer sensing
duration can improve detection accuracy. However, it reduces
transmission time of the secondary users, which essentially decreases
the aggregate throughput. Thus, we also design an adaptive duration
system to jointly optimize sensing duration with thresholds of energy
detectors and the linear weights to further improve the
aggregate throughput for the secondary users.
History
Advisor
Liu, DerongDepartment
Electrical and Computer EngineeringDegree Grantor
University of Illinois at ChicagoDegree Level
- Doctoral
Committee Member
Mazumder, Sudip Zefran, Milos Rao, Wenjing DasGupta, BhaskaSubmitted date
2014-05Language
- en