R.K. Martin, M. Ding, B.L. Evans, and C.R. Johnson, Jr.
To appear in IEEE Transactions on Signal Processing, first quarter 2004.
We show that maximum shortening SNR TEQs are often nearly symmetric. Constraining the TEQ to be symmetric causes only a 3% loss in bit rate (averaged over 8 standard ADSL channels). Symmetric TEQs have greatly reduced design and implementation complexity. We also show that for infinite length TEQs, minimum mean squared error target impulse responses have all zeros on the unit circle, which can lead to poor bit rate performance.