EP0100593A2
Expired / Lapsed
EP
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Improved time slot arrangements for local area network systems
Assignee: Plessey Semiconductors Ltd
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Filing: 1983-06-15
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Granted: —
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Expires: 2003-06-15
Abstract
Abstract In local area networks (LAN's) which are required to operate in duplex mode it is necessary for the common communication medium to be operated in a t.d.m. manner. Because the LAN has no common equipment, every station is arranged to contain its own control circuitry and crystal controlled clocking system to produce time slot markers. The system is organised so that each time slot comprises an active period for data or speech transmission or contention resolution, followed by a transit period in which the data or speech reaches the destination. Ideally time slot markers occur simultaneously in both stations and for intermediate stations there is a tolerance which reaches a maximum at the midway point of the network communication medium. The multiplexing system arranges that the time slots are packed as closely together as the delay between most separated stations will allow. The near simultaneous occurrance of time slot markers is maintained by all stations whether busy or free by observing the timing of traffic on the communication medium and adjusting the timing of the station time slot marker to occur in the time between data or speech bursts of existing traffic.
Inventors
- 👤 Raymond Beaufoy
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 19:47
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/407; H04L12/413
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
170 words
A communication system comprising a common communication medium and a plurality of subscribers interface units each connected to the common communication medium and each interface unit includes a data transmission arrangement for transmitting information signals on to the communication medium and a data reception arrangement for receiving information signals from the communication medium, the communication medium being arranged to carry information on a time division multiplex basis in which each time slot includes an active period for the transmission of a burst of information signals and a transit period and each interface unit includes internal timing arrangements arranged to produce timing signals on a time division multiplex basis with each slot including an active period and a transit period and each interface unit includes means for monitoring the timing of traffic bursts on the communication medium and means for adjusting the internal timing arrangements within the interface unit so that the time slot timing cycle within the interface unit corresponds with that of the data signals on the communication medium.
Claim 2
Dependent Claim
170 words
A communication system comprising a common communication medium and a plurality of subscribers interface units each connected to the common communication medium and each interface unit includes a data transmission arrangement for transmitting information signals on to the communication medium and a data reception arrangement for receiving information signals from the communication medium, the communication medium being arranged to carry information on a time division multiplex basis in which each time slot includes an active period for the transmission of a burst of information signals and a transit period and each interface unit includes internal timing arrangements arranged to produce timing signals on a time division multiplex basis with each slot including an active period and a transit period and each interface unit includes means for monitoring the timing of traffic bursts on the communication medium and means for adjusting the internal timing arrangements within the interface unit so that the time slot timing cycle within the interface unit corresponds with that of the data signals on the communication medium.
Claim 3
Dependent Claim
59 words
A communication system as claimed in Claim 1 in which the internal timing arrangements of an interface unit are arranged to generate a time slot marker at the mid point of the transit period of each internal time slot and the means for monitoring is arranged to generate a time slot marker relevant to the communication medium time slots.
Claim 4
Dependent Claim
52 words
A communication system as claimed in Claim 2 in which the internal timing arrangements comprise a source of clock pulses driving a time slot timing device and a frame timing device and the setting of these devices is controlled by detection means sensitive to a predetermined discrepancy between the time slot markers.
Claim 5
Dependent Claim
46 words
A communication system as claimed in Claim 3 in which the detection means is arranged to set the time slot timing device to zero when the time slot marker on the common communication medium occurs during the active period of the interface unit internal timing cycle.
Claim 6
Dependent Claim
53 words
A communication system as claimed in Claim 4 in which the detection means is arranged to set the time slot timing device to zero at the start of an active period if the internal timing cycle time slot marker would occur in the leading half of the active period on the communication medium.
Claim 7
Dependent Claim
53 words
A communication system as claimed in Claim 4 in which the detection means is arranged to set the time slot timing device to zero at the end of an active period if the internal timing cycle time slot marker would occur in the trailing half of the active period on the communication medium.
Claim 8
Dependent Claim
80 words
A communication system as claimed in any preceding claim in which each interface unit comprises (i) a time slot processor incorporating (a) said means for monitoring the timing of traffic bursts, (b) said internal timing arrangements and said detection means, (ii) a message buffer providing storage for information signals to be passed to and received from said communication medium and (iii) a system processor interfacing said time slot processor and message buffer to the subscriber's equipment connected to the interface.
Claim 9
Dependent Claim
16 words
A communication system as claimed in Claim 7 in which the interface unit is microprocessor controlled.
Claim 10
Dependent Claim
30 words
A data communication system as claimed in Claim 8 in ! which the common communication medium provides a local area network incorporating both data handling equipment and voice communication equipment.
Claim 11
Dependent Claim
26 words
A data communication system as claimed in Claim 9 in which each time slot on the communication medium comprises a go period and a return period.
Claim 12
Dependent Claim
51 words
A data communication system as claimed in Claim 10 in which an interface unit is arranged to generate an addressing packet when initiating a correction to the common communication medium, said addressing packet defining the address of the, or each other equipment interface unit with which a communication correction is required.
Claim 13
Dependent Claim
26 words
A data communication system as claimed in Claim 11 in which the identity of the required other equipment interface unit is applied in the go period.
Claim 14
Dependent Claim
41 words
A data communication system as claimed in Claim 12 in which during a duplex communication interchange using the communication medium a traffic packet is applied to the same channel in each frame of the time division multiplex cycle of the medium.
Claim 15
Dependent Claim
56 words
A data communication system as claimed in Claim 13 in which the time division multiplex basis of the common communication medium may be suspended to permit a long continuous burst of data at maximum communication medium transmission rate to be transmitted and each interface unit includes means for accumulating its traffic packets during the suspended period.
References Cited (Backward Citations)
No citation records indexed.
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