Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: For a ring communication system, an access mechanism is provided and supported by medium access control means so that different kinds of traffic are optimally accommodated. Signaling information (SG) and isochronous data (IS) keep their position in a synchronous time raster while propagating on the ring, whereas variable-length data frames (DF A, DF B, DF C, DF D) can be relatively shifted in their position during propagation on the ring, to allow for the insertion of additional variable-length data frames (DF E, DF F), thus giving to all stations attached to the ring a fair chance for transmitting such data frames (DF). The data frames are partitioned into slot-size segments, and the mechanism guarantees that the segments of any data frame will not be interrupted by segments of another such data frame.

Abstract: A ring communication system comprises distribution panels (13) for inserting extension lines (15) and attached stations (19) into the communication ring (11); insertion is requested and controlled by DC signaling from the station via a phantom path. To allow attachment of several stations via additional extension lines (25) to a single basic extension line (15), extension distribution panels (23) are provided comprising line insertion modules (31) like the basic distribution panels. Insertion of a station and its additional extension line (25) up to the EXP is still controlled by DC signaling from the station, but insertion of the basic extension line (15) is controlled by a tone signal transferred from the EXP to the basic distribution panel via a phantom path. The EXP (23) needs no own power supply because DC power is provided from the basic distribution panel (13) via the phantom circuit of the basic extension line.

Abstract: In a switching exchange for circuit-switched/synchronous traffic (CS) and packet-switched/asynchronous data packet traffic (PS), transmission lines communicate with FIFO buffers interconnected by a data bus on which information is transferred in periodic frames. CS traffic is collected in FIFO input buffers in minipackets each carrying a local routing address. The last minipacket per frame period is identified by a special end tag. Once per frame a daisy-chain signal propagates through access control lines to sequentially read out from FIFO input buffers all CS minipackets up to the next one having a special end tag, transferring them through the data bus to FIFO output buffers. Thereafter a token access mechanism starts enabling selective PS data packet transfer between FIFO input and output buffers. When a new frame begins, and PS data packet transfer is interrupted for a CS minipacket readout process, and thereafter transfer of the interrupted PS packet is resumed.

Abstract: In a local area communication system comprising token rings (11) with synchronous bandwidth managers SBM (15) for issuing priority tokens for quasi-synchronous frames at regular intervals, the rings are interconnected by a time division muliplex PBX unit (21) via their SMB units. Buffers are provided in each SBM for synchronous information blocks transferred from and to the ring, and the TDM control (31) can independently access these buffers for TDM switching of the individual bytes of said information blocks. Besides this PBX interconnection for synchronous information or voice, the rings are also interconnected by a backbone bus or ring for transfer of asynchronous data between rings. A special slot rearrangement procedure is provided to improve the filling of time slots in the quasi-synchronous frames that are no longer used after release of a connection, to allow for adapting the frame length (number of issued slots) to the number of existing connections.

Abstract: In a communication system providing multiple access to transmission facilities for a plurality of stations (17, 21), two separate networks (11, 13) are provided: One is a token ring (11) on which access tokens and data are transmitted, the other is a high-speed optical fiber transmission ring (13) on which only large-volume data blocks are transmitted between particular stations (21) which are attached to both rings, but no access information. A token manager (27) in the token ring (11) provides at regular intervals particular tokens that are only used by the particular stations (21) for obtaining access to the high-speed ring (13), but also provides other tokens for regulating access to the token ring (11) for other stations (17). Special access nodes (23) are provided which allow to connect the particular stations (21) to the high-speed ring (13) without extending its length.