§
Luxuse
Patent Intelligence
Sign In
← Back to Patent Explorer
EP0147994A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Reconfigurable collision avoiding system, station and protocol for a two path multiple access digital communications system

Assignee: AT&T Inc
•
Filing: 1984-12-18
•
Granted: —
•
Expires: 2004-12-18
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract In order to control the transfer of packets of information among a plurality of stations, e.g., digital computers, the instant communications system, station and protocol contemplate first (10) and second (60) oppositely directed signal paths. At least two stations are coupled to both the first and the second signal paths. A station (70-i) includes arrangements for reading (20-i, 40-i) (and writing (30-i, 50-i)) signals from (and on) each of the two-paths. Signals are read from either path by an arrangement which electrically precedes the arrangement for writing signals on the path. If the station has a packet to transmit, it can overwrite a busy control field of a packet on either path. Also having read a packet signal from the path, a logical interpretation may be made within the station as to whether the path is busy or is not busy. If the path is not busy, the packet may be written on the path by overwriting any signal thereon. If the path is busy, the station may defer the writing until the path is detected as not busy e.g. by reading a busy control field of another packet. Here the two paths are coupled to form two ring structures so the packets flow down the path to a destination station. Eventually all packets will be transmitted and the busy control field loops around to a station which is designated as a control station (70-(1,N)). The control station, responsive to detecting that all packets have been transmitted on one of the paths, may transmit a start cycle packet on the one path, responsive to which event a new cycle may be started by initializing each station on the one path and by permitting each initialized station to transmit. In the event of an electrical open (500), the system, station and protocol are adapted to reconfigure the system so that the station (70-i) electrically preceding the open functions as an end station while the station (70-(i+ 11) electrically succeeding the open functions as a head station.

Inventors

  • 👤 Frank Howard Levinson
  • 👤 John Ormond Limb

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-01 21:54
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/42; H04L12/40; H04L12/407; H04L12/417

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 191 words
A method for controlling digital signals in a communications system, the system including a plurality of stations, at least two of the stations being coupled to both a first and a second signal path, the method including the steps of: writing signals on the first path; reading signals from the first path, the first path reading step occurring electrically before the writing on the first path; reading signals from the second path; writing signals on the second path, the second path writing step occurring electrically after the reading from the second path; CHARACTERIZED IN THAT the method further comprising the steps of: reading a busy control field of a packet by a control station which is coupled to both of the signal paths; and responsive to the read busy control field indicating that a respective one of the paths is not busy, initiating a start cycle packet on the one path, the start cycle packet being transmitted by the control station on the one path and the start cycle packet including a start cycle field responsive to which a station on the one path may be initialized to transmit a packet.
Claim 2
Independent Claim 191 words
A method for controlling digital signals in a communications system, the system including a plurality of stations, at least two of the stations being coupled to both a first and a second signal path, the method including the steps of: writing signals on the first path; reading signals from the first path, the first path reading step occurring electrically before the writing on the first path; reading signals from the second path; writing signals on the second path, the second path writing step occurring electrically after the reading from the second path; CHARACTERIZED IN THAT the method further comprising the steps of: reading a busy control field of a packet by a control station which is coupled to both of the signal paths; and responsive to the read busy control field indicating that a respective one of the paths is not busy, initiating a start cycle packet on the one path, the start cycle packet being transmitted by the control station on the one path and the start cycle packet including a start cycle field responsive to which a station on the one path may be initialized to transmit a packet.
Claim 3
Dependent Claim 25 words
The method defined in claim 1 wherein the first path and the second path are, respectively, unidirectional paths and wherein the paths are oppositely directed.
Claim 4
Dependent Claim 46 words
The method defined in claim 1 further comprising the step of overwriting a busy control field of a first packet by a station on the one path with a signal for indicating that the overwriting station has a second packet to transmit on the one path.
Claim 5
Dependent Claim 44 words
The method defined in claim 1 further comprising the step of responsive to detecting an electrical open in either of the signal paths, adapting a first station to function as a head station and adapting a second station to function as an end station.
Claim 6
Dependent Claim 22 words
The method defined in claim 4 wherein the first station electrically succeeds the open and the second station electrically precedes the open.
Claim 7
Dependent Claim 229 words
A communications system.comprising: a first (10) and a second (60) communications signal path, the signal paths being oppositely directed; a plurality of stations (20-N), each of at least two of the stations being coupled to both the first and the second signal paths, the station (20-i) comprises; first means for writing a first signal on the first path, second means for reading a second signal from the first path, the first path reading means being coupled to the first path in a manner electrically preceding the first path writing means; third means for reading a third signal from the second path, fourth means for writing a fourth signal on the second path, the second path writing means being coupled to the second path in a manner electrically succeeding the second path reading means; CHARACTERIZED IN THAT the system further comprises: means for reading the contents of a busy control field of a signal read from one of the paths and means, responsive to the read signal busy control field indicating that the one path is not busy, for initiating a start cycle packet on the one path, the start cycle packet being transmitted by a control station on the one path and the start cycle packet including a start cycle field responsive to which a station on the respective path may be initialized and permitted to transmit a packet.
Claim 8
Dependent Claim 229 words
A communications system.comprising: a first (10) and a second (60) communications signal path, the signal paths being oppositely directed; a plurality of stations (20-N), each of at least two of the stations being coupled to both the first and the second signal paths, the station (20-i) comprises; first means for writing a first signal on the first path, second means for reading a second signal from the first path, the first path reading means being coupled to the first path in a manner electrically preceding the first path writing means; third means for reading a third signal from the second path, fourth means for writing a fourth signal on the second path, the second path writing means being coupled to the second path in a manner electrically succeeding the second path reading means; CHARACTERIZED IN THAT the system further comprises: means for reading the contents of a busy control field of a signal read from one of the paths and means, responsive to the read signal busy control field indicating that the one path is not busy, for initiating a start cycle packet on the one path, the start cycle packet being transmitted by a control station on the one path and the start cycle packet including a start cycle field responsive to which a station on the respective path may be initialized and permitted to transmit a packet.
Claim 9
Dependent Claim 21 words
The system in accordance with claim 6 CHARACTERIZED IN THAT the first path and the second path are respective unidirectional paths.
Claim 10
Dependent Claim 46 words
The system in accordance with claim 6 CHARACTERIZED IN THAT the system responsive to detecting an electrical open in either of the signal paths, for adapting a first station to function as a head station for adapting a second station to function as an end station.
Claim 11
Dependent Claim 25 words
The system in accordance with claim 8 CHARACTERIZED IN THAT the first station electrically succeeds the open and the second station electrically precedes the open.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag