Communications method for a shared-medium communications method
First Claim
1. A communications method for a shared-medium communications network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction, said method comprising:
- transmitting data between, to and from said stations on said buses in packets, or slots, of data during each of a plurality of cycles;
said stations requesting the use of a slot for data transmission by placing a request signal on the bus which transmits data in a direction opposite to the desired direction of transmission, each request signal being either a non-guaranteed bandwidth request for use of a slot on a first request, first use priority or a guaranteed bandwidth request for use of a slot without regard to first request, first use priority;
satisfying non-guaranteed bandwidth requests for use of a slot by said stations on a first request, first use priority;
satisfying guaranteed bandwidth requests for use of a slot by said stations without regard to first request, first use priority; and
providing an allocation, for at least one of said stations, limiting the number of request signals for guaranteed bandwidth traffic which a station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority.
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Abstract
A communications method for a shared-medium communications network having a plurality of stations connected by a first and second bus. The first bus is for data transmission in one direction and the second bus is for data transmission in an opposite direction. The method includes transmitting data between stations in slots. A station desiring to transmit requests the use of a slot by placing a request signal on the bus in a direction opposite to the desired direction of transmission. A slot is then used on a first request, first use priority except for a least one station which is allocated a slot without regard to the first request first use priority. This allocation provides for guaranteed bandwidth traffic.
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Citations
26 Claims
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1. A communications method for a shared-medium communications network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction, said method comprising:
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transmitting data between, to and from said stations on said buses in packets, or slots, of data during each of a plurality of cycles; said stations requesting the use of a slot for data transmission by placing a request signal on the bus which transmits data in a direction opposite to the desired direction of transmission, each request signal being either a non-guaranteed bandwidth request for use of a slot on a first request, first use priority or a guaranteed bandwidth request for use of a slot without regard to first request, first use priority; satisfying non-guaranteed bandwidth requests for use of a slot by said stations on a first request, first use priority; satisfying guaranteed bandwidth requests for use of a slot by said stations without regard to first request, first use priority; and providing an allocation, for at least one of said stations, limiting the number of request signals for guaranteed bandwidth traffic which a station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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2. A communications method for a shared-medium communications network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction, said method comprising:
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transmitting data between, to and from said stations on said buses in packets, or slots, of data during each of a plurality of cycles; said stations requesting the use of a slot for data transmission by placing a request signal on one of the buses, each request signal being either a non-guaranteed bandwidth request for use of a slot on a first request, first use priority or a guaranteed bandwidth request for use of a slot without regard to first request, first use priority; satisfying non-guaranteed bandwidth requests for use of a slot by said stations on a first request, first use priority; satisfying guaranteed bandwidth requests for use of a slot by said stations without regard to first request, first use priority; and providing an allocation, for at least one of said stations, limiting the number of request signals for guaranteed bandwidth traffic which a station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority.
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13. A station in a shared-medium communications network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction, said station comprising
means for receiving, processing and outputting packets, or slots, of data transmitted on said two buses during each of a plurality of cycles; -
means for requesting the use of a slot for data transmission by placing a request signal on one of the busses, each request signal being either a non-guaranteed bandwidth request for use of a slot on a first request, first use priority or a guaranteed bandwidth request for use of a slot without regard to first request, first use priority; means for satisfying non-guaranteed bandwidth requests for use of a slot on a first request, first use priority, comprising means for maintaining a request count which represents the number of request signals representing requests for use of slots on the basis of said first request, first use priority, said request count being decremented accordingly when an available slot is allowed by the station to pass on the other bus; means for satisfying guaranteed bandwidth requests for use of a slot without regard to first request, first use priority, comprising means for maintaining a request outstanding count which represents the number of requests made by the station without regard to the first request, first use priority and which have not been satisfied; and means for providing an allocation limiting the number of request signals for guaranteed bandwidth traffic which the station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority, comprising means for maintaining a remaining request count which represents the number of requests which the station can make without regard to the first request, first use priority, said remaining request count being decremented when the station issues such a request. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A shared-medium communications network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction;
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at least one of the stations comprising means for receiving, processing and outputting packets, or slots, of data transmitted on said two buses during each of a plurality of cycles; means for requesting the use of a slot for data transmission by placing a request signal on the bus which transmits data in a direction opposite to the desired direction of transmission, each request signal corresponding to one of a plurality of priority levels including a guaranteed priority level, requests corresponding to a high priority level being satisfied before requests corresponding to a low priority level, each request signal corresponding to the guaranteed priority level being a guaranteed bandwidth request for use of a slot without regard to first request, first use priority within the guaranteed priority level, each request signal corresponding to one of the other priority levels being a non-guaranteed bandwidth request for use of a slot on a first request, first use priority within the other priority level; means for satisfying non-guaranteed bandwidth requests for use of a slot on a first request, first use priority; means for satisfying guaranteed bandwidth requests for use of a slot without regard to first request, first use priority; and means for providing an allocation limiting the number of request signals for guaranteed bandwidth traffic which the station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority;
whereinthe two buses are terminated by units which maintain counts of request signals received and issue available slots for data transmission, and the network enters an idle state when an available slot is issued on one of said buses and k consecutive slots, without request signals for the guaranteed priority level or higher, have been received by a terminating unit on the other bus, k being a positive integer. - View Dependent Claims (22, 23, 24)
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25. A shared-medium communication network having a plurality of stations connected in series by first and second buses, the first bus being for data transmission in one direction and the second bus being for data transmission in an opposite direction,
at least one of said stations comprising means for receiving, processing and outputting packets, or slots, of data transmitted on said two buses during each of a plurality of cycles; -
means for requesting the use of a slot for data transmission by placing a request signal on the bus which transmits data in a direction opposite to the desired direction of transmission, each request signal corresponding to one of a plurality of priority levels including a guaranteed priority level, requests corresponding to a high priority level being satisfied before requests corresponding to a low priority level, each request signal corresponding to the guaranteed priority level being a guaranteed bandwidth request for use of a slot without regard to first request, first use priority within the guaranteed priority level, each request signal corresponding to one of the other priority levels being a non-guaranteed bandwidth request for use of a slot on a first request, first use priority within the other priority level; means for satisfying non-guaranteed bandwidth requests for use of a slot on a first request, first use priority; means for satisfying guaranteed bandwidth requests for use of a slot without regard to first request, first use priority; and means for providing an allocation limiting the number of request signals for guaranteed bandwidth traffic which the station can issue during each cycle to obtain the use of slots without having regard to said first request, first use priority; the remaining stations satisfying requests only on the basis of said first request, first use priority and being unable to issue requests corresponding to said guaranteed priority level. - View Dependent Claims (26)
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Specification