International Business Machines Corporation

Peter L Heinzmann

Johann R Mueller

Mehdi M Nassehi

Fritz R Gfeller

Oliver Martin

There is provided a method of regulating access to a unidirectional bus transmission system to which a plurality of stations identified by labels are connected, on which system data are transmitted in time slots which are released in numbered cycles by a headend unit, and in which said headend unit sends, for each of said cycles, a request poll message carrying the respective cycle number. The method comprises i) logically combining a source station label and a destination station label, ii) deriving a first control number from the logical combination of the source station label and the destination station label, iii) using, for requesting slots in which to transmit said data, a request poll message carrying a cycle number which corresponds to said first control number, and iv) subsequently transmitting said data in slots of a cycle whose number corresponds to said first control number.

Communications network and method of regulating access to the busses in

This invention relates to a remotely optically powered fiber optic switch, e.g. in a fiber optic network, and a GRIN-rod (Graded-Refractive-Index-rod) lens with integrated planar mirror as a switching element, in particular suited for fiber optic switches. A distribution panel, in which the switching element, a wavelength-division demultiplexer, a light-into-current converter, and an actuator for the switching element are situated, is remotely optically powered from a station in the network. Part of this station is a laser diode which feeds a powering lightwave via a wavelength-division multiplexer into an optical fiber interconnecting the station with the distribution panel, which fiber can also be used for data transmission. The light-into-current converter receives the powering lightwave and generates an electric current for driving the actuator and moving the switching element. A GRIN-rod lens with integrated planar mirror serves as switching element by rotating it in a ferrule and establishing different light paths depending on the position of the integrated mirror with respect to lightwaves optically coupled to the end facets of the GRIN-rod.

Fiber optic switch with remote optical powering

In a communication system comprising node stations connected to a bus, a headend unit releases, for sequentially numbered cycles, time slots as previously requested in an order pad passing procedure. In the order pad procedure, the headend issues a special frame in which stations insert the number of slots required to transmit data in a subsequent cycle. To enable reuse of time slots which otherwise would be utilized only during a fraction of their existence (i.e. from a source to a destination which in many cases are located close together), the order pad additionally includes a furthest destination label (DST-MAX) and a requested maximum (REQ-MAX) which are updated at each node. This allows to set, for any cycle, at some nodes a reuse flag (REU-FLG). In this way, the bus is partitioned into sections according to actual traffic, and the headend only releases a number of time slots which satisfies the needs of the section where the maximum of time slots was requested. Thus, the number of time slots, i.e. the length of each cycle can be significantly reduced, thereby increasing system throughput.

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Windlach, Switzerland

Peter L Heinzmann