THE EFFECTS OF DESTRUCTIVE INTERFERENCE AND WASTED TRANSMISSIONS ON THE UNIFORM-TRAFFIC CAPACITY OF NON-BUS-ORIENTED SINGLE-HOP INTERCONNECTIONS

The uniform-traffic capacity of switchless, non-bus-oriented, fiber-op tic single-hop interconnections among N stations, each equipped with a small number of transmitters and receivers, can be as high as Theta(l og(2) N) concurrent transmissions on a single wavelength with round-r obin scheduling in a time-slotted system. Hoc-ever, their capacity wit h the slotted ALOHA access scheme does not increase with N. (The capac ity of bus-oriented interconnections, in contrast, varies across time- slotted access schemes by, at most, a factor of e.) This paper quantif ies the contribution of several factors to capacity. Merely avoiding d estructive interference with ongoing receptions contributes, at most, a factor of e over slotted ALOHA, the same as in bus-oriented intercon nections. For an interconnection among two-transmitter, single-receive r stations, whose capacity is log(2) N with global scheduling and 2/e with slotted ALOHA, also avoiding transmissions to blocked receivers i ncreases capacity to, at most, log(2) log(2) N. These results suggest that the added complexity of non-bus-oriented SHI's may be warranted o nly if they are operated in ways that permit the selection of ''good'' combinations of (source, destination) pairs for concurrent transmissi on, and further research should focus on those.