초록 ▼

Examples of local communication systems are disclosed, based on a ring of point-to-point links, providing for transport of fixed rate synchronous, fixed rate asynchronous data and variable rate data in a flexible format. Different segments of the ring network can carry data at different bit rates, w

Examples of local communication systems are disclosed, based on a ring of point-to-point links, providing for transport of fixed rate synchronous, fixed rate asynchronous data and variable rate data in a flexible format. Different segments of the ring network can carry data at different bit rates, while remaining synchronized to a common frame rate and having a common control channel structure, for compatibility with earlier systems. Parallel channels are provided, either permanently or when required, for signalling errors of source data, data validity/padding, flow control. Parallel variable width channels are defined with free content (stream or packet). Null data symbols are defined for padding on a byte-by-byte basis. The allocation of capacity among variable width channels is revised block by block, and a transition period is defined to allow for ring latency. Calculations for allocation of capacity are performed during one block for the next block, locally at each source station, according to predetermined rules. Information as to bandwidth requirements is exchanged prior to the calculation via a special connection signalling channel and message format.

대표청구항 ▼

1. A local communication system comprising:a plurality of stations interconnected by data carrying segments so as to form a ring network, each station comprising a network interface for transmitting data onto a respective segment of the ring network for receipt by the network interface of a subseque

1. A local communication system comprising:a plurality of stations interconnected by data carrying segments so as to form a ring network, each station comprising a network interface for transmitting data onto a respective segment of the ring network for receipt by the network interface of a subsequent station, whereby the network interfaces of all stations are operable at data rates synchronized with a single master clock, and wherein the network interfaces of at least two stations in the system are operable such that the data rate in a first segment of the ring is higher than that in a second segment of the ring, while remaining synchronized with said master clock, wherein synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of the first segment, and wherein each frame conveys control bits forming part of a control message frame transmitted over plural frames over all segments of the ring, successive control message frames forming a control channel shared by all stations of the ring network and having a constant data rate for control information in all segments. 2. A system as in claim 1, including means for synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.3. A network interface for use in interfacing a station to a local communication system comprising a synchronous ring network, each station in use being connected between incoming and outgoing segments of the ring network, the interface comprising:means for transmitting data onto the outgoing segment of the ring network for receipt by a subsequent station, the interface being operable, at least in a mixed-speed mode, to transmit data on the outgoing segment at a data rate synchronized with but different to the rate of data received on the incoming segment, wherein in said mixed speed mode, synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of one of said segments, and wherein each frame conveys control bits forming part of a control message frame transmitted over plural frames over both incoming and outgoing segments of the ring, successive control message frames forming a control channel shared by all stations of the ring network and having a constant data rate for control information in all segments. 4. An interface as in claim 3 including means for synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.5. An apparatus for use as a station in a local communication system, the apparatus comprising at least one functional unit and a network interface circuit as in claim 3.6. An apparatus as in claim 5 wherein said functional unit comprises a source of destination of audio data.7. A local communication method for use with a plurality of stations interconnected by data carrying segments so as to form a ring network, each station comprising a network interface for transmitting data onto a respective segment of the ring network for receipt by the network interface of a subsequent station, said method comprising:operating the network interfaces of all stations at data rates synchronized with single master clock, and operating the network interfaces of at least two stations in the system such that the data rate in a first segment of the ring is higher than that in a second segment of the ring, while remaining synchronized with said master clock, wherein synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of the first segment, and wherein each frame conveys control bits forming part of a control message frame transmitted over plural frames over all segments of the ring, successive control message frames forming a control channel shared by all stations of the ring network and having a constant data rate for control information in all segments. 8. A method as in claim 7, including synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.9. A network interface method for use in interfacing a station to a local communication system comprising a synchronous ring network, each station in use being connected between incoming and outgoing segments of the ring network, the method comprising:transmitting data onto the outgoing segment of the ring network for receipt by a subsequent station, operating the interface, at least in a mixed-speed mode, to transmit data on the outgoing segment at a data rate synchronized with but different to the rate of data received on the incoming segment, wherein in said mixed speed mode, synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of one of said segments, and wherein in said mixed speed mode, each frame conveys control bits forming part of a control message frame transmitted over plural frames over all segments of the ring, successive control message frames forming a control channel shared by all stations of the ring network and having a constant data rate for control information in all segments. 10. An interface method as in claim 9 including synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.11. Method for use as a station in a local communication system, the method comprising use of at least one functional unit and a network interface method as in claim 9.12. A method as in claim 11 wherein said functional unit comprises a source or destination of audio data.13. A local communication system comprising:a plurality of stations interconnected by data carrying segments so as to form a ring network, each station comprising a network interface for transmitting data onto a respective segment of the ring network for receipt by the network interface of a subsequent station, whereby the network interfaces of all stations are operable at data rates synchronized with a single master clock, and wherein the network interfaces of at least two stations in the system are operable such that the data rate in a first segment of the ring is higher than that in a second segment of the ring, while remaining synchronized with said master clock, wherein synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of the first segment, and wherein each frame conveys at least one bit forming part of a message frame transmitted over plural frames over all segments of the ring, successive message frames forming a messaging channel which is shared by all stations of the ring network and which has constant data rate in all segments. 14. A system as in claim 13 including means for synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.15. A network interface for use in interfacing a station to a local communication system comprising a synchronous ring network, each station in use being connected between incoming and outgoing segments of the ring network, the interface comprising:means for transmitting data onto the outgoing segment of the ring network for receipt by a subsequent station, the interface being operable, at least in a mixed-speed mode, to transmit data on the outgoing segment at a data rate synchronized with but different to the rate of data received on the incoming segment, wherein in said mixed speed mode, synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of one of said segments, and wherein each frame conveys at least one bit forming part of a message frame transmitted over plural frames over both incoming and outgoing segments of the ring, successive message frames forming a messaging channel which is shared by all stations of the ring network and which has a constant data rate in all segments. 16. An interface as in claim 15 including means for synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.17. An apparatus for use as a station in a local communication system, the apparatus comprising at least one functional unit and a network interface circuit as in claim 15.18. A local communication method for use with a plurality of stations interconnected by data carrying segments so as to form a ring network, each station comprising a network interface for transmitting data onto a respective segment of the ring network for receipt by the network interface of a subsequent station, said method comprising:operating the network interfaces of all stations at data rates synchronized with single master clock, and operating the network interfaces of at least two stations in the system such that the data rate in a first segment of the ring is higher than that in a second segment of the ring, while remaining synchronized with said master clock, wherein synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of the first segment, and wherein each frame conveys at least one bit forming part of a message frame transmitted over plural frames over all segments of the ring, successive message frames forming a control channel shared by all stations of the ring network and having a constant data rate for control information in all segments. 19. A method as in claim 18 including synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.20. A network interface method for use in interfacing a station to a local communication system comprising a synchronous ring network, each station in use being connected between incoming and outgoing segments of the ring network, the method comprising:transmitting data onto the outgoing segment of the ring network for receipt by a subsequent station, operating the interface, at least in a mixed-speed mode, to transmit data on the outgoing segment at a data rate synchronized with but different to the rate of data received on the incoming segment, wherein in said mixed speed mode, synchronization is maintained by the provision of a regular frame structure which has the same frame period in both segments of the network, but a larger quantity of data in each frame of one of said segments, and wherein in said mixed speed mode, each frame conveys at least one bit forming part of a message frame transmitted over plural frames over all segments of the ring, successive message frames forming a messaging channel which is shared by all stations of the ring network and has a constant data rate for control information in all segments. 21. An interface method as in claim 20 including synchronizing one or more digital audio data sources, for which source data is carried in the fixed rate portions of each frame, with the data rates of the interface.22. Method for use as a station in a local communication system, the method comprising use of at least one functional unit and a network interface method as in claim 20.23. A method as in claim 22 wherein said functional unit comprises a source or destination of audio data.24. A method for operating a ring data communications network to concurrently service interconnected devices, the required capacity for data being substantially higher between certain of said devices than between others, said method comprising:transmitting from device to device successive frames occupying successive equal time periods; transmitting the same number of bits for control data in each said frame to form a control data channel shared by all stations of the ring network; and transmitting different numbers of bits for other data in respectively corresponding different ones of said frames to form a plurality of ring link segments having different capacity for said other data to respectively corresponding different stations of the ring network. 25. An apparatus as in claim 17 wherein said functional unit comprises a source or destination of audio data.