Peak load access in a two-way CATV contention system
First Claim
1. In a two-way contention communications system wherein a data message is successively transmitted from a subscriber terminal to a central facility until the data message is successfully received by the central facility, each data message transmission occurring at a random time within a respective time interval, the improvement comprising the steps of:
- increasing the length of said time interval in response to each successive transmission of said data message until a time interval of a predetermined maximum length is achieved corresponding to a predetermined number of successive transmissions of said data message; and
decreasing the length of said time interval in response to each of a selected number of succesive transmission of said data message following said predetermined number of successive transmissions.
3 Assignments
0 Petitions
Accused Products
Abstract
In a two-way cable television (CATV) contention system peak upstream loading is accommodated by varying the length of the upstream transmission window during which a subscriber may randomly transmit for improved subscriber access to the CATV headend. Following an upstream transmission, the subscriber waits a predetermined period for a message receipt acknowledgment from the headend. Failure to receive this acknowledgment results in an upstream retransmission by the subscriber at a randomly selected time within a transmission window, the length of which is a function of the upstream message traffic load. The transmission window is initially short to permit rapid retransmissions upstream in order to avoid interfering noise bursts of short duration. The upstream transmission window is then increased in length to a maximum value to string out upstream transmissions during a peak access period for reducing upstream message collisions. Following upstream transmissions during the maximum transmission window, the window is then reduced in length to accommodate reduced upstream traffic following successful upstream communication by the majority of subscribers. This upstream transmission distribution arrangement improves subscriber headend access, namely system throughput, by increasing the transmission window during periods of peak access and shortening the window length following peak access periods in order to reduce the time required for a successful upstream transmission.
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Citations
16 Claims
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1. In a two-way contention communications system wherein a data message is successively transmitted from a subscriber terminal to a central facility until the data message is successfully received by the central facility, each data message transmission occurring at a random time within a respective time interval, the improvement comprising the steps of:
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increasing the length of said time interval in response to each successive transmission of said data message until a time interval of a predetermined maximum length is achieved corresponding to a predetermined number of successive transmissions of said data message; and decreasing the length of said time interval in response to each of a selected number of succesive transmission of said data message following said predetermined number of successive transmissions. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for transmitting data from a plurality of subscriber terminals to a headend in a two-way CATV contention communication system, comprising:
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providing a transmission instruction at a subscriber terminal; successively transmitting a single data message in response to said transmission instruction from the subscriber terminal to the headend, each data message transmission occurring at a random time within a respective time interval which initially increases in length in response to each successive transmission of said data message until a time interval of a predetermined maximum length is achieved corresponding to a predetermined number of successive data message transmissions whereupon the length of the time interval decreases in response to each of a selected number of successive transmissions of said data message following said predetermined number of successive transmissions; generating an acknowledge signal at the central facility in response to the successful receipt of a transmitted data message from the subscriber terminal; transmitting the acknowledge signal from the central facility to the subscriber terminal; and withdrawing said transmission instruction following the receipt by said subscriber terminal of said acknowledge signal for terminating said repeated transmissions. - View Dependent Claims (8)
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9. In a two-way contention communcations system wherein a data message is successively transmitted from a subscriber terminal to a central facility until the data message is successfully received by the central facility, each data message transmission occurring at a random time within a respective time interval, the improvement comprising:
means for increasing the length of said time interval in response to each successive transmission of said data message until a time interval of a predetermined maximum length is achieved corresponding to a predetermined number of successive transmissions of said data message and for decreasing the length of said time interval in response to each of a selected number of successive transmissions of said data message following said predetermined number of successive transmissions. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A two-way CATV contention communication system for transmitting data from a plurality of subscriber terminals to a headend, comprising:
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means for providing a transmission instruction at a subscriber terminal; means for successively transmitting a single data message in response to said transmission instruction from the subscriber terminal to the headend, each data message transmission occurring at a random time within a respective time interval which initially increases in length in response to each successive transmission of said data message until a time interval of a predetermined maximum length is achieved corresponding to a predetermined number of successive data message transmissions whereupon the length of the time interval decreases in response to each of a selected number of successive transmissions of said data message following said predetermined number of successive transmissions; means for generating an acknowledge signal at the central facility in response to the successful receipt of a transmitted data message from the subscriber terminal; means for transmitting the acknowledge signal from the central facility to the subscriber terminal; and means for withdrawing said transmission instruction following the receipt by said subscriber terminal of said acknowledge signal for terminating said successive transmissions. - View Dependent Claims (16)
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Specification