C. Antweiler et M. Dorbecker, PERFECT SEQUENCE EXCITATION OF THE NLMS ALGORITHM AND ITS APPLICATIONTO ACOUSTIC ECHO CONTROL, Annales des telecommunications, 49(7-8), 1994, pp. 386-397
Adaptive echo cancellers are currently being studied for applications
such as audio teleconference systems or hands-free telephone sets with
high speech quality. The purpose of the echo control is to eliminate
the acoustic feedback from the loudspeaker to the microphone. One prob
lem of echo cancellers using e.g. the normalized least mean square alg
orithm (NLMS) for the adaptation of the coefficients is that the conve
rgence properties degrade with colored signal input such as speech sig
nals [8, 9, 17]. One approach to accelerate the convergence speed is t
o introduce linear prediction filters in order to decorrelate the spee
ch signal [1, 2, 12, 15, 20]. This paper presents a new approach, name
d the excited LMS algorithm or ELMs algorithm, which prewhitens the in
put signal applying perfect sequences. Coincidently, the proposed algo
rithm can be interpreted as a combination of the conventional NLMS alg
orithm and a system identification approach using m-sequences or relat
ed sequences.