PASSIVE STAR-CONFIGURED OPTICAL LAN USING CSMA WITH A NOVEL COLLISION DETECTOR.

A description is given of the design and theoretical performance of a passive star-configured multimode-optical-fiber local area network that uses carrier-sense multiple access with collision detection (CSMA/CD). A collision detection method is introduced that uses collision sequences constructed from cyclic error-correcting codes and a sequence weight violation rule. Each transmitter has its own unique sequence, and all sequences have identical Hamming weight. The collision-detection sequence is inserted in each packet header. The method allows detection of collisions subject to a wider dynamic range variation than competing methods. The collision detector is analyzed for an avalanche photodiode receiver. A dynamic range of 17 dB seems possible for a transmitter with an extinction ratio of 100 and a simple receiver with a fixed threshold.