An initial trial of the optical fiber transmission system in NTT is reported in this paper. In NTT's transmission networks, the shorthaul application appears attractive in the near future. The laboratory test is primarily targeted to 32 Mb/s bit rate and 8 km long repeater spacing. We report here the design philosophy of step-index multimode fibers and repeaters for this trial. Through the design and manufacturing of fibers, the fundamental and common characteristics of fibers are clarified. Stable, compact and low power consuming optical repeaters are realized. Trere is no trouble of optical repeatered line and all repeaters in the line are operating with sufficient optical power margin. Multi-repeatered test has confirmed that experimental results are in good agreement with the design values.

A novel multiple-access optical network architecture is presented that not only employs the WDM technique but also divides networks. The subnetworks are connected to each other via a wavelength-dependent interconnection network, and pairs of subnetworks are optically linked with different combinations for each wavelength. Through an analysis of the throughput and delay for the slotted ALOHA protocol, the architecture is confirmed to be improved from the conventional one that employs only the WDM technique. For example, the improvement ratio of the throughput for a four-wavelength network is 2.4, and that for an eight-wavelength network is 4.4.