Performance Analysis of Blind Equalization Algorithms for Broadcast Channel
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Date
2017-11
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Addis Ababa University
Abstract
Wireless channels exhibit multipath and time dispersion that lead to attenuation
and inter-symbol interference (ISI). In order to compensate the effect of ISI caused by
channels, equalization techniques are introduced on receiver ends. The increasing
demand for high-speed data transmission over band limited channels makes the
applications of training-based equalization methods more challenging due to constant
transmission of the pilot signals/training sequences which consumes a lot of bandwidth
and power. Blind equalizations, a category of equalization techniques, requires no
training sequences to track and compensation the effect of ISI channel. These
equalizations are applicable in many practical areas such as audio broadcasting in
which training-based equalizations are not mainly applied and use only the received
signals to equalize the channel.
This thesis focuses on the performance analysis of three blind equalization
techniques; namely, Variable Step Size Constant Modulus Algorithm (VSS-CMA),
Decision Feedback Equalizer Constant Modulus Algorithm (DFE-CMA) and joint
VSSCMA-Decision Directed Least Mean Square (DDLMS) algorithm for application in
audio broadcasting. To ease visualization of results and see the effect of changing
various parameters a Graphical User Interface (GUI) is developed. Comparison of the
results of the above three blind equalization algorithms were compared with two
additional blind equalization algorithms: Constant Modulus Algorithm (CMA) and
Multi Modulus Algorithm (MMA).
The simulation results are evaluated using Mean Square Error (MSE), symbols
constellation plots, convergence rate, computation time and complexity as performance
metrics. Rectangular 16-Quadrature Amplitude Modulation (QAM) scheme, ISI channel
with Additive White Gaussian Noise and three other channel models for GUI
simulation are considered.
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Keywords
Broadcast Channel, Blind Equalization, Blind Equalization Algorithms