Data communication system with prioritized periodic and aperiodic messages
First Claim
1. In a data communications system having inbound and outbound communication channels on which a central station and a plurality of remote terminal units operate, a slotted CSMA contention arrangement for selectively controlling the operation of such remote terminal units, comprising in combination:
- said inbound channel being divided into a plurality of standardized microslots of a given duration and wherein said outbound channel is adapted to convey inbound channel busy status information; and
means for prioritizing access to the inbound channel by the remote units when transmitting periodic and aperiodic messages thereon,said remote units being permitted to transmit periodic messages at the start of the first microslot after the inbound channel is sensed not busy, and to transmit aperiodic messages only after waiting an additional one microslot to determine the inbound channel remains not busy.
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Accused Products
Abstract
A slotted CSMA contention technique and arrangement is disclosed for use in a radio data communications systems having a central base station/controller and a plurality of remote data terminals operating over inbound and outbound channels. The channels are divided into major frames, which are further divided into minor frames, which in turn are divided into microslots. An arrangement is devised whereby channel access may be prioritized as between periodic and aperiodic messages by advantageously utilizing the occurrence of these microslots so as to give priority to the former while completely eliminating collisions therebetween and, at the same time, optimally controlling the efficiency of the system as a whole.
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Citations
16 Claims
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1. In a data communications system having inbound and outbound communication channels on which a central station and a plurality of remote terminal units operate, a slotted CSMA contention arrangement for selectively controlling the operation of such remote terminal units, comprising in combination:
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said inbound channel being divided into a plurality of standardized microslots of a given duration and wherein said outbound channel is adapted to convey inbound channel busy status information; and means for prioritizing access to the inbound channel by the remote units when transmitting periodic and aperiodic messages thereon, said remote units being permitted to transmit periodic messages at the start of the first microslot after the inbound channel is sensed not busy, and to transmit aperiodic messages only after waiting an additional one microslot to determine the inbound channel remains not busy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a data communications system having inbound and outbound communication channels on which a central station and a plurality of remote terminal units operate, a method for selectively controlling the system remote terminal units by a slotted CSMA technique, comprising the step of:
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dividing the inbound channel into a plurality of standardized microslots of a given duration and utilizing the outbound channel to convey inbound channel busy status information; and prioritizing access to the inbound channel by the remote units when transmitting periodic and aperiodic messages thereon, permitting remote units to transmit periodic messages at the start of the first microslot after the inbound channel is sensed not busy, but aperiodic messages only after waiting an additional one microslot to determine the inbound channel remains not busy. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification