Digital Subscriber-Loop Performance Using Echo-Cancellation with WAL I and WAL II Coding

The performance of the echo-cancelling method of transmission using the WAL I and WAL II line codes is investigated for a loop model which is based on a statistical survey of the subscriber loopnetwork in New Zealand. Extensive simulation results are given for linear equalizers and decision-feedback equalizers operating at 144 kbit/s. It is found that, provided a good sampling phase can be assumed, simple DFE's and WAL I line code are generally adequate for a loop population penetration of over 95 percent.