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:

  1. prof.dr.ing. Silviu Ciochina – project manager
  2. S.l.dr.ing. Constantin Paleologu
  3. S.l.ing. Radu Mihnea Udrea
  4. As.ing. Alexandru Alexandru Enescu
  5. As.ing. Anghel Cristian

 

Project presentation

 

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:

  1. S. Ciochină, C. Paleologu, J. Benesty, A. A. Enescu, “On the Influence of the Forgetting Factor of the RLS Adaptive Filter in System Identification”, Proc. IEEE International Symposium on Signals, Circuits and Systems (ISSCS), pp. 205-208, Iaşi, România, Iulie 2009.
  2. C. Anghel, C. Paleologu, J. Benesty, S. Ciochină, “FPGA Implementation of an Acoustic Echo Canceller Using a VSS-NLMS Algorithm”, Proc. IEEE International Symposium on Signals, Circuits and Systems (ISSCS), pp. 369-372, Iaşi, România, Iulie 2009.
  3. C. Paleologu, J. Benesty, S. Ciochină, C. Vlădeanu, “Practical Variable Step-Size Adaptive Algorithms for Echo Cancellation”, Proc. Int. Conference on Speech Technology and Human-Computer Dialogue (SpeD), pp. 181-188, Constanţa, Romania, Mai 2009.
  4. C. Paleologu, A. A. Enescu, S. Ciochină, F. Albu, “QRD-LSL Adaptive Algorithms Suitable for Fixed-Point Implementation”, Proc. IEEE Advanced International Conference on Telecommunications (AICT), pp. 163-167, Veneţia, Italia, Mai 2009. (Best Paper Award)
  5. C. Paleologu, S. Ciochina, J. Benesty, “Double-Talk Robust VSS-NLMS Algorithm for Under-Modeling Acoustic Echo Cancellation”, IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP 2008, Las Vegas, U.S.A.
  6. C. Paleologu, F. Albu, A.A. Enescu, S. Ciochina, “Square-Root-Free QRD-LSL Adaptive Algorithm with Improved Numerical Robustness”, IEEE International Conference on Networking, ICN 2008, Cancun
  7. C. Paleologu, J. Benesty, S. Ciochina, "Robust Variable Step-Size Affine Projection Algorithm Suitable for Acoustic Echo Cancellation", EUSIPCO 2008, Lausanne, Switzerland.
  8. C. Paleologu, S. Ciochina, A.A. Enescu, C. Vladeanu, "Gradient Adaptive Lattice Algorithm Suitable for Fixed Point Implementation", ICDT 2008, Bucharest, Romania.

 

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