Tetsuo Soejima

A distributed restoration algorithm for multiple-link and node failures of transport networks

Fast restoration of broadband optical fiber networks from multiple-link and node failures, as well as single-link failures, is addressed. A distributed restoration algorithm based on message flooding is described. The algorithm is an extension of a previously proposed algorithm for single-link failure. It restores the network from multiple-link and node failures, using multidestination flooding and path route monitoring. Computer simulation of the algorithm verified that it can find alternate paths within 0.5 s, whenever the message processing delay at a node is 5 ms.<<ETX>>

Experimental Bidirectional Subscriber Loop Transmission System

This paper describes a complete hardware implementation of an experimental two-wire digital subscriber loop transmission system using balanced pairs of wires. It is based on the time division burst mode transmission scheme (ping-pong), and provides two information channels, 64 kbits/s and 8 kbits/s, and a signaling channel both ways. The burst cycle is 2 ms and line transmission rate is 192 kbits/s. The salient feature of the system is that it is equipped with a powerful bridged tap equalizer which has the capability to compensate a large fraction of existing two-wire subscriber loops in Japan. It is realized by a fifth-order recursive filter using analog tapped delay lines, and a modified zero forcing algorithm is adopted for the adaptation of the tap coefficients. The experimental results showed that the combination of the \sqrt{f} AGC and the bridged tap equalizer enables the digital transmission up to 4 km on the 0.4 mm φ subscriber line with three bridged taps each of 400 m length.