A study on subscriber optical line‐switching networks

In subscriber optical line networks, it is necessary to take measures to accompany the reliability improvements to efforts concerning the increases in the speed of information communications and the diversity of the services. In this paper, in regards to the structure of the line switching of the loop networks, the optimized settling method of the switch and its structure are investigated. The efficient switching method, in case of a failure, also is shown. Finally, the results of the trial manufacturing of the switch with the required functions are discussed. As the network structure, the one with its feeder lines pulled into many loop lines in one central office is modelled. In such network structures, exclusive protection lines are accommodated, taking into account the circuit failure ratio and the efficiency of line usage, etc. The switching is possible at the branching points of the feeder and the distribution lines between the service and the protection lines. By attaching the switching possibility at the feeding and crossing points to the protection lines, failure of one loop network is shown to be relieved effectively. Finally, the four-terminal switch possessing the required functions in regards to the present line-switching networks is proposed and compared against the usual 1 × 2 and 2 × 2 switches. It is shown that it is possible to realize the line-switching networks with considerably reduced number of switches. Then, from the trial manufacturing results, the possibility of realization of high-speed and low-loss switches is indicated.