Title :
A study of two adaptive filters in tandem
Author_Institution :
Dept. of Electr. Eng., Missouri Univ., Columbia, MO, USA
fDate :
6/1/2000 12:00:00 AM
Abstract :
The tandem of adaptive filters is common in practice. An example is the tandem of echo cancellers in telecommunication networks. This paper analyzes the convergence characteristics and tracking behavior of two adaptive filters in tandem, together with a comparison of its performance with a single adaptive filter. The adaptive algorithm considered is the LMS and the analysis is on mean-square. The coefficient errors correspond to noise, lag bias and lag variance are examined separately The theoretical results are corroborated with simulations. The study shows that the tandem of two adaptive filters decreases the convergence speed compared to a single adaptive filter. In addition, in steady state and when the step-size is small tandeming increases the coefficient variance due to noise by a factor of 2.5, the coefficient variance due to tracking lag by a factor of 1.5, but decreases the mean-square coefficient bias due to lag by a factor of 2
Keywords :
Markov processes; adaptive filters; adaptive signal processing; convergence of numerical methods; echo suppression; filtering theory; least mean squares methods; telecommunication networks; telephony; tracking filters; LMS adaptive algorithm; coefficient errors; coefficient variance; convergence characteristics; convergence speed; echo cancellers; first-order Markov model; lag bias; lag variance; mean-square analysis; mean-square coefficient bias; noise; performance; simulations; step-size; tandem adaptive filters; telecommunication networks; telephone connection; tracking behavior; tracking lag; Adaptive filters; Circuits; Convergence; Delay; Echo cancellers; Least squares approximation; Noise cancellation; Speech; Telephony; Testing;
Journal_Title :
Signal Processing, IEEE Transactions on
