2 research outputs found
A novel array signal processing technique for multipath channel parameter estimation
Cataloged from PDF version of article.Many important application areas such as mobile communication, radar, sonar
and remote sensing make use of array signal processing techniques. In this thesis,
a new array processing technique called Cross Ambiguity Function - Direction
Finding (CAF-DF) is developed. CAF-DF technique estimates direction of arrival
(DOA), time delay and Doppler shift corresponding to each impinging signals
onto a sensor array in an iterative manner. Starting point of each iteration is
CAF computation at the output of each sensor element. Then, using incoherent
integration of the computed CAFs, the strongest signal in the delay-Doppler domain
is detected and based on the observed phases of the obtained peak across
all the sensors, the DOA of the strongest signal is estimated. Having found
the DOA, CAF of the coherently integrated sensor outputs is computed to find
accurate delay and Doppler estimates for the strongest signal. Then, for each
sensor in the array, a copy of the strongest signal that should be observed at that
sensor is constucted and eliminated from the sensor output to start the next iteration.
Iterations continue until there is no detectable peak on the incoherently
integrated CAFs. The proposed technique is compared with a MUSIC based technique on synthetic signals. Moreover, performance of the algorithm is tested
on real high-latitude ionospheric data where the existing approaches have limited
resolution capability of the signal paths. Based on a wide range of comparisons,
it is found that the proposed CAF-DF technique is a strong candidate to define
the new standard on challenging array processing applications.Güldoğan, Mehmet BurakM.S
Development of new array signal processing techniques using swarm intelligence
Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.Thesis (Ph. D.) -- Bilkent University, 2010.Includes bibliographical references leaves 144-158.In this thesis, novel array signal processing techniques are proposed for identifi-
cation of multipath communication channels based on cross ambiguity function
(CAF) calculation, swarm intelligence and compressed sensing (CS) theory. First
technique detects the presence of multipath components by integrating CAFs of
each antenna output in the array and iteratively estimates direction-of-arrivals
(DOAs), time delays and Doppler shifts of a known waveform. Second technique
called particle swarm optimization-cross ambiguity function (PSO-CAF) makes
use of the CAF calculation to transform the received antenna array outputs to
delay-Doppler domain for efficient exploitation of the delay-Doppler diversity of
the multipath components. Clusters of multipath components are identified by
using a simple amplitude thresholding in the delay-Doppler domain. PSO is
used to estimate parameters of the multipath components in each cluster. Third
proposed technique combines CS theory, swarm intelligence and CAF computation.
Performance of standard CS formulations based on discretization of the
multipath channel parameter space degrade significantly when the actual channel
parameters deviate from the assumed discrete set of values. To alleviate this
“off-grid”problem, a novel technique by making use of the PSO, that can also be
used in applications other than the multipath channel identification is proposed.
Performances of the proposed techniques are verified both on sythetic and real
data.Güldoğan, Mehmet BurakPh.D