Data packet transmission using shared channel
First Claim
1. A method of transmitting data from a source device to a predetermined destination device in a system comprising a plurality of devices, a plurality of interface means, and a common communications channel, each device being coupled to the channel through an associated one of the said interface means, only one of the interface means at a time being permitted to transmit a packet over the channel, the method comprising transferring the data from the source device to its interface means in individual data units with no indication of how the data units are to be grouped into packets, storing the units in storage means in that interface means, and, when the interface means is permitted to transmit a packet, transmitting a packet comprising all the data units stored in the said storage means and not previously transmitted.
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Accused Products
Abstract
In a data communication system an interface unit connects a device to a common communications channel shared with other devices using e.g. a carrier-sense multiple-access protocol. Individual bytes for a predetermined destination device are supplied by the device to communications controller 6 without any grouping into packets. They are then stored in a RAM 8 under control of a microcomputer 5. As soon as a byte is received, the interface unit attempts to transmit a packet; when the right to transmit is won the interface unit transmits a packet containing that and any subsequent bytes. The length of the packet therefore depends on the delay before a packet can be transmitted, and hence on the loading on the channel.
133 Citations
15 Claims
- 1. A method of transmitting data from a source device to a predetermined destination device in a system comprising a plurality of devices, a plurality of interface means, and a common communications channel, each device being coupled to the channel through an associated one of the said interface means, only one of the interface means at a time being permitted to transmit a packet over the channel, the method comprising transferring the data from the source device to its interface means in individual data units with no indication of how the data units are to be grouped into packets, storing the units in storage means in that interface means, and, when the interface means is permitted to transmit a packet, transmitting a packet comprising all the data units stored in the said storage means and not previously transmitted.
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8. Interface apparatus for coupling an associated device to a common communications channel to which are coupled a plurality of other devices each through an interface means separate from the said interface apparatus, the interface apparatus in operation being permitted to transmit a packet only at intervals in such a manner as to share the use of the channel with the interface means of the other devices and comprising:
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(a) input means for receiving individual data units from the said associated device supplied without any indication of how they should be grouped into packets, (b) storage means for storing data units received from the associated device and (c) outputting means operative, when the interface apparatus is permitted to transmit a packet, to output for transmission over the common communications channel packet destined for a predetermined destination device and comprising all those data units stored in the storage means and not previously transmitted as part of a packet. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A data communication system comprising a communications channel, a plurality of devices, a plurality of interface means each connecting an associated one of the devices to the channel, and means for permitting only one of the interface means at a time to transmit a packet over the channel, wherein each interface means comprises:
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(a) input means for receiving individual data units from the said associated device applied without any indication of how they should be grouped into packets, (b) storage means for storing data units received from the associated device and (c) outputting means operative, when the interface means is permitted to transmit a packet, to output for transmission over the communications channel packet comprising all those data units stored in the storage means and not previously transmitted as part of a packet.
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Specification