This document outlines a method for solving the permutation switching problem that can occur with online independent component analysis (ICA) under non-stationary environments. The method takes correlations of the overlap between signal blocks and connects the separated signals by checking the correlation values. Numeric experiments show the method successfully solves the permutation switching problem under both stationary and small non-stationary environments. Future work is needed to address separating signals under more significantly changing environments.

1. Solving Permutation Switching Problem
of Online ICA
under non-stationary environment
by using Cross-Correlation of Output
Yuuki Nakayama, s1130164
Supervised by Prof. Shuxue Ding
Foundation of Computer Science Laboratory

2. Outline
• Independent Component Analysis (ICA)
• Motivation
• Method
• Numeric experiment 1
• Numeric experiment 2
• Conclusion

3. Independent Component Analysis (ICA)
• The technique for separate signals from mixed
signal
Drawback : Cannot use real world because of batch processing
↓
Solution : online ICA It can use real time.
Drawback : causing permutation switching problem

4. Motivation
• Permutation Switching Problem
One separated signal may connect to a wrong component signal.
Separated signal (Permutation Switching happened )
Solution : Using Cross-Correlation Matrix

5. Method
• Taking correlations of overlap part between
two blocks
• Connecting “unmix (signals)” by checking
correlation values

6. Numeric experiment 1
• Stationary Environment
Original signals Separated signals Performance of SIR
Permutation switching problem have been successful solved under stationary environment

7. Numeric experiment 2
• Non-stationary Environment (small changing environment)
Original signals Separated signals Performance of SIR
Permutation switching problem have been successful solved under non-stationary environment

8. Conclusion
• The solving permutation switching problem
has been successful.
• Future works
→ The algorithm which can separated signals under big changing
environment is needed