Blind System Identification
Vincent Neo, Patrick Naylor
The channel impulse response often carries important information about the system such as time delays in wireless communications, radar and sonar. Furthermore, the impulse response could also be used to recover the original source like seismic source in geophysics and vital signs in medical applications. In acoustic systems, the task for the latter is termed as dereverberation.
For most practical systems, there is often no prior information on the original source and only the received signal(s) is/are available which leads to the class of “blind” problems. Since it is increasingly common to have more than one microphone on electronic devices – mobile phones, laptops, tablets etc., this multi-channel setup has provided opportunities to exploit redundancy and extract useful information to help solve the problem.
The so-called cross-relation method uses an adaptive approach to exploit the structure of the second order statistics, that is computed from the multi-channel data, to estimate the channel impulse response. If further useful information is available, it could be used as useful constraints to guide the adaptation process to arrive at the correct estimate.