Robust
Solutions for Adaptive Interference Cancelling
Solutii robuste pentru suprimarea adaptiva a interferentelor [Romana]
PN-II-PCE IDEI ID_1027
Project summary
This project relies on the fact
that one of the most known adaptive configurations, called interference
surpression, works abnormal in many practical cases, for both rls and lms
algorithm families. Typical to this configuration is the existence of an
external signal of significant values. Hence, a first objective is to localize
and describe these malfunctions. In lms algorithms, a divergence phenomenon
occurs and in rls case, a residual leakage through the error signal phenomenon
may appear. The latter was first discovered within the team proposing this
project. Secondly, the project intends to solve this issue. We underline two
different situations that need different approaches: the case of non-permanent
excitation signal and the case of permanent excitation signal. Proposed solutions
target new versions for lms/nlms algorithms with variable step size for the
first case and modified rls algorithms for the second case. Theoretical
approaches will be supported by a convincing set of simulations. Moreover, we
propose implementing the proposed solutions on both dsp and fpga - based
platforms. The fourth goal refers to the applications where such algorithms may
be used. These will be oriented towards line echo cancellers, acoustic echo
cancellers, noise surpressers and adaptive beamformers for interference
reduction. The final part is validating the solution via measurements in
compliance with the current reglementations where applicable.
Research team:
Project objectives
1.
To
achieve a deep analysis of the phenomenon occuring in the “interference
surpression” configuration, meaning an adaptive configuration with secondary
external signal.
2.
To
give a precise characterization of the residual signal leakage through the
error signal for RLS-based algorithms.
3.
To
give solutions for a non-permanent excitation. It is expected that such
solutions exist for LMS algorithms with variable step size, bringing better
solutions with respect to the current ones.
4.
On
the practical aspect, this could mean algorithms with superior performances for
line echo adaptive cancelers or for acoustic echo (hands-free systems,
teleconference systems etc.)
5.
To
give solutions for permanent excitation. Obviously, these can be used also for
non-permanent excitation, but it may lead to very complex solutions. Our target
is RLS-based algorithms family.
6.
The
previous aspect may further extend to adaptive noise surpression systems and to
adaptive antenna systems with automatic beamforming.
7.
To
analyze the performances of the proposed algorithms, in the context of the
target application classes.
8.
To
analyze aspects related to the practcical implemenattion of the algorithms in
finite-precision. We target the fixed point implementation.
9.
To
effectively implement the proposed algorithms on two different platforms:
digital signal processors (DSPs) and field programmable gate arrays (FPGAs).
10.
To
perform lab measurements in order to evaluate the performances and the
compliance with the existing standards if applicable.
The team will develop an intensive dissemination
activity, targeting to obtain a broad recognition of the contributions in the field
of the project and on the other side, to find potential partners in the
economic field, interested in a technology transfer process.
Dissemination
Results:
Conference papers:
Journal papers:
1.
C. Paleologu, F. Albu, A. A. Enescu, S. Ciochină, “Modified SRF-QRD-LSL
Adaptive Algorithm with Improved Numerical Robustness”, International Journal On Advances in Systems and Measurements, vol.
2, no. 1, pp. 56-65, 2009. http://www.iariajournals.org/systems_and_measurements/tocv2n1.html
2. C. Paleologu, J. Benesty, S.
Ciochină, “A
Family of Variable Step-Size NLMS Algorithms for Echo Cancellation”, Revue
Roumaine des Sciences Techniques – Serie Electrotechnique et Energetique,
vol. 54, no. 3, 2009, în curs de
apariţie. abstract
3. C. Paleologu, J. Benesty, S. Ciochină, “A Variable Step-Size Affine Projection Algorithm Designed for Acoustic Echo Cancellation”, IEEE Transactions on Audio, Speech, and Language Processing, vol. 16, no. 8, pp. 1466-1478, Nov. 2008. abstract
4. C. Paleologu, J. Benesty, S. Ciochina, "A Robust Variable Forgetting Factor Recursive Least-Squares Algorithm for System Identification", IEEE Signal Processing Letters, vol. 15, pp. 597-600, 2008. abstract
5. C. Paleologu, J. Benesty, S. Ciochina, "A Variable Step-Size Proportionate NLMS Algorithm for Echo Cancellation", Revue Roumaine des Sciences Techniques - Serie Electrotechnique et Energetique, vol. 53, no. 3, pp. 309-317, 2008. abstract
6. C. Paleologu, S. Ciochina, J. Benesty, "Variable Step-Size NLMS Algorithm for Under-Modeling Acoustic Echo Cancellation", IEEE Signal Processing Letters, vol. 15, pp. 5-8, 2008. abstract