EP0209383A2
Expired / Lapsed
EP
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Communications method
Assignee: British Telecommunications PLC
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Filing: 1986-07-16
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Granted: —
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Expires: 2006-07-16
Abstract
Abstract A network for carrying real-time (RTS) and data services comprises stations (12) on a ring (11). Frames on the ring have a fixed boundary (15) between a real-time portion of the frame and a data portion. A sequence of cycles is initiated by a priority station. During a refresh cycle a bit map on the ring is marked by each station in turn to indicate which slots in the real-time portions are occupied. Next the stations bid for slots needed for new calls. During a third cycle information transfer for RTS calls takes place. After these cycles, priority is passed to the next station. The data portion may use a slotted ring or token ring data control protocol, and data transfer proceeds during RTS cycles. In an alternative version the boundary (15') may be relocated periodically depending on the level of real-time traffic.
Inventors
- 👤 Robert Charles Turner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 20:27
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/64; H04L12/28; H04L12/42; H04L12/427; H04L12/43
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
138 words
A communications network comprising a plurality of stations (12) and a link (11) for communication between the stations in which encoded information is carried in frames; each of said frames having a real-time portion with time slots for real-time calls, and a data portion for signalling information: characterised in that a bit map is transferred between the stations indicating whether each real-time time slot is free or in use; and said frames are transmitted in cycles consisting of one or more frames; said cycles comprising a refresh cycle during which new seizures of real-time slots are prevented, said bit map is reset and stations transmitting real-time calls sequentially reclaim previously seized slots, and a bidding cycle in which stations are allowed to sequentially set up new real-time calls by seizing free time slots in said real time portion.
Claim 2
Dependent Claim
35 words
A communications network according to claim 1 wherein frames are generated by a priority station having priority status and frames are seized sequentially during refresh cycles and during bidding cycles starting from the priority station.
Claim 3
Dependent Claim
18 words
A communications network according to claim 2 wherein priority status is sequentially passed to all of the stations.
Claim 4
Dependent Claim
41 words
A communications network according to any preceeding claim wherein each station includes means for detecting a priority error which occurs when no station has priority status or when two or more stations have priority status, including means for resetting the system.
Claim 5
Dependent Claim
30 words
A communications network according to claim 4 wherein the first station which detects a priority error disables the other stations and then assumes priority status afer a predetermined delay period.
Claim 6
Dependent Claim
31 words
A communications network according to any preceedng claim in which a bidding cycle is followed by one or more ordinary cycles during which calls are transmitted but slots are not seized.
Claim 7
Dependent Claim
21 words
A communications network according to claim 6 in which the number of ordinary cycles following a bidding cycle is randomly variable.
Claim 8
Dependent Claim
28 words
A communications network according to claim 7 in which the number of ordinary cycles between a bidding cycle and the next refesh cycle is either one or two.
Claim 9
Dependent Claim
25 words
A communications network according to claim 8 when dependent on claim 3 in which priority status is transferred after said one or two ordinary cycles.
Claim 10
Dependent Claim
21 words
A communications network according to any preceeding claim in which a proportion of each frame is reserved for the bit map.
Claim 11
Dependent Claim
19 words
A communications network according to claim 10 in which the bit map is distributed over a plurality of frames.
Claim 12
Dependent Claim
23 words
A communications network according to claim 11, in which extra bits are provided in the bit map to facilitate a cyclic redundancy check.
Claim 13
Dependent Claim
24 words
A communications network according to any preceeding claim in which the data portion also carries user related data in addition to the signalling information.
Claim 14
Dependent Claim
29 words
A communications network according to claim 13, in which a boundary between the real-time portion and the data portion may be adjusted to accommodate changes in relative traffic densities.
References Cited (Backward Citations)
EP0079426A1
Cited
EP0118767A2
Cited
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