EP0173364A1
Expired / Lapsed
EP
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Method, station and system for the transmission of messages in the form of data packets
Assignee: Koninklijke Philips NV
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Filing: 1985-07-10
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Granted: —
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Expires: 2005-07-10
Abstract
Abstract A method of transmitting data packets in a message-switched channel (signalling channel) of a time-division multiplex system with CSMA-CD. Interference-free transmission in the message-switched channel ensures the absence of collisions on occupying the circuit-switched connection. Message mutilation and collision on accessing the message-switched channel are remedied by a retransmission procedure in which the unique station address number determines the frame number in which the retransmission may start. This procedure guarantees that a station accesses the message-switched channel within a very short period of time. This guaranteed access is not possible with the prior art CSMA-CD buses.
Inventors
- 👤 Wouter Bourgonje
- 👤 Daniel Johannes Gerardus Janssen
- 👤 Willem Albert Van Reede
- 👤 Johannes Adrianus Alphonsus Vossen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 09:45
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/403; H04L12/4035; H04L12/407; H04L12/413; H04M; H04M9/00; H04M9/02; H04M9/022; H04M9/025
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
211 words
A method of transmitting messages formed by data packets between stations via a common communication channel formed by corresponding time slots in consecutive frames of a time-division multiplex system, - each station continuously checking the traffic state (free or busy) of the channel, - those stations which have a data packet ready for transmission transmitting this packet after they have detected the traffic-free state of the channel, - each transmitting station comparing the content of the data packet this station transmits to the content of the data packet present in the communication channel to check those packets for mutilations, - each station detecting mutilation of its data packet terminating the transmission of further data packets of the message, - whereafter those stations which have detected mutilation of the data packets adopting a procedure for repeated transmission of the data packets, characterized in that: - each station has an address number which unambiguously identifies this station, - after mutilation of data packets has been detected, consecutive numbers are assigned in each station to a first number of consecutive frames, and - the number of the frame in which the re-transmission of the data packets of a station starts is equal to at least a portion of the address number of that station.
Claim 2
Independent Claim
211 words
A method of transmitting messages formed by data packets between stations via a common communication channel formed by corresponding time slots in consecutive frames of a time-division multiplex system, - each station continuously checking the traffic state (free or busy) of the channel, - those stations which have a data packet ready for transmission transmitting this packet after they have detected the traffic-free state of the channel, - each transmitting station comparing the content of the data packet this station transmits to the content of the data packet present in the communication channel to check those packets for mutilations, - each station detecting mutilation of its data packet terminating the transmission of further data packets of the message, - whereafter those stations which have detected mutilation of the data packets adopting a procedure for repeated transmission of the data packets, characterized in that: - each station has an address number which unambiguously identifies this station, - after mutilation of data packets has been detected, consecutive numbers are assigned in each station to a first number of consecutive frames, and - the number of the frame in which the re-transmission of the data packets of a station starts is equal to at least a portion of the address number of that station.
Claim 3
Dependent Claim
85 words
A method as claimed in Claim 1, characterized in that - after mutilation of the data packets has been detected, consecutive numbers are assigned in all stations to a second number of consecutive frames which considered in the time precede the first number of consecutive frames, and - the number of the frame of the second number in which, if necessary a second retransmission of the data packets of a station starts is equal to the other portion of the address number of that station.
Claim 4
Dependent Claim
43 words
A method as claimed in Claim 1 or 2, characterized in that each station which has detected that a data packet has been mutilated transmits after this detection a disturb signal for mutilating further data packets before starting to follow the retransmission procedure.
Claim 5
Dependent Claim
64 words
A method as claimed in Claim 1, 2 or 3, characterized in that - data packets of first and second types are transmittable, these types differing from each other by their contents, and - in the traffic-free state, of consecutive pairs of frames the first and second frames are alternately available for the transmission of a packet of the first and second type, respectively.
Claim 6
Independent Claim
101 words
A method as claimed in any one of the preceding Claims, characterized in that - data packets of the first and second types are transmittable by the stations, these types differing from each other by their contents, - each station can start the transmission of data packets of the first type in a frame located between the instant at which mutilation of a data packet was detected and the subsequent assigning of consecutive numbers for consecutive frames, and - in each station a flag is set which indicates the transmission of a data packet of the first type in said frame.
Claim 7
Independent Claim
114 words
A method as claimed in any one of the preceding Claims, characterized in that - after the transmission of the message has been completed, the receiving stations effect an error check, - in each station after completion of the transmission of the message consecutive numbers are assigned to a first number of consecutive frames, which number is immediately subsequent to the last data packet of the message, - each station which detects an error during the error check transmits an alarm signal in a predetermined frame of the first number, and - that station which has sent the erroneously transmitted message starts to follow a procedure for retransmission in response to the alarm signal.
Claim 8
Independent Claim
119 words
A method of selecting a main station for transmitting synchronizing signals in a system comprising a communication channel and a synchronizing signal for performing the method as claimed in any one of the preceding Claims, characterized in that - in each station the address number of that station is used as a presetting of a counter, - the counting position of this counter is always incremented by one unit under the control of a local clock which is nominally the same for all stations until in one of the stations a predetermined final position, which is identical for all stations, is reached, and - the station reaching this final state starts to transmit synchronizing signals via the synchronizing channel.
Claim 9
Dependent Claim
175 words
A station suitable for performing the method as claimed in Claim 1, this station comprising: - a receiver for receiving data packets from the communication channel, - a transmitter for transmitting data packets to the communication channel, and - a channel comparator for comparing the data packets which are simultaneously present at the transmitter output and in the communication channel, this channel comparator generating a collision signal on detection of inequality between the data packets, characterized in that the station further comprises: - an address store for storing the address number of the station, - a frame counter for storing the frame numbers of the first number of frames, - a counter comparator for comparing the content of the frame counter to the first-mentioned portion of the address number, the counter comparator in the event of equality generating an energizing signal, - a buffer memory for storing the data packets to be transmitted, - and energizing means which in response to the energizing signal cause the transmitter to transmit the content of the buffer store.
Claim 10
Dependent Claim
74 words
A station as claimed in Claim 8, for performing the method as claimed in Claim 6, characterized in that - this station comprises an alarm signal detector for detecting alarm signals in the communication channel, the detector on detecting an alarm signal generating an alarm indication signal, and - this station comprises a re-transmission counter for increasing the content of this counter in response to collision signals and in response to alarm indication signals.
Claim 11
Dependent Claim
70 words
A system of stations having a common communication channel and a common synchronizing channel for performing the method as claimed in Claim 7, characterized in that - at least one station is connectable to an external communication channel constituted by a sequence of frames, and - the most significant figure of the address number of this station is one unit higher than the most significant figure of the other stations.
Claim 12
Independent Claim
64 words
A system of stations having a communication channel for performing the method as claimed in one of the Claims 1 to 7, inclusive, the content of the data packets being binary encoded and the communication channel being realised by a conductor of electromagnetic activity characterized in that one of the two values of the binary code is represented by the absence of electromagnetic activity.
References Cited (Backward Citations)
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