P-persistent carrier sense multiple access (CSMA) for non-packetized wireless digital voice networks
First Claim
Patent Images
1. A communications system, comprising:
- a plurality of radios that form a CSMA wireless communications network and communicate non-packetized digital voice with each other using single channel all-informed communications among the radios;
each radio being configured to determine the end of conversations in a transmission and operative for dividing a period following the end of a received transmission into a sequence of time slots, and in each time slot, deciding randomly or pseudo-randomly with probability p whether to start transmitting on the channel in that slot based on an estimate whether channel contention is likely, provided that a new transmission has not been detected on the channel prior to the start of the slot.
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Abstract
A communications system includes a plurality of radios that form a CSMA wireless communications network to communicate none-packetized digital voice with each other. Each radio is operative for dividing the period following the end of a received transmission into a sequence of time slots, each having a duration at least equal to an effective end-to-end traffic latency. In each time slot, the radio decides randomly with probability p whether to start transmitting on the channel in that slot, provided that a new transmission has not been detected on the channel prior to the start of the slot.
13 Citations
32 Claims
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1. A communications system, comprising:
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a plurality of radios that form a CSMA wireless communications network and communicate non-packetized digital voice with each other using single channel all-informed communications among the radios; each radio being configured to determine the end of conversations in a transmission and operative for dividing a period following the end of a received transmission into a sequence of time slots, and in each time slot, deciding randomly or pseudo-randomly with probability p whether to start transmitting on the channel in that slot based on an estimate whether channel contention is likely, provided that a new transmission has not been detected on the channel prior to the start of the slot. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for communicating digital voice, which comprises:
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receiving within a radio a non-packetized digital voice communications signal over a CSMA wireless communications channel as single channel, all-informed communications among a plurality of radios in a CSMA wireless communications network; determining the ends of conversations in a transmission and dividing a period following the end of a received transmission into a sequence of time slots; and in each time slot, deciding randomly or pseudo-randomly with probability p whether to start transmitting on the channel in that slot based on an estimate whether channel contention is likely, provided that a new transmission has not been detected on the channel prior to the start of the slot. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for communicating digital voice, which comprises:
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receiving within a radio a non-packetized digital voice communications over a CSMA wireless communications channel as single channel, all-informed communications among a plurality of radios in a CSMA wireless communications network; determining the ends of conversations in a transmission and determining at the radio the start time of a sequence of transmit time slots; determining which of the transmit time slots in the sequence of transmit time slots is a first slot in which the radio can transmit; and determining randomly or pseudo-randomly with probability p whether to start transmitting on the channel in successive slots based on an estimate whether channel contention is likely, wherein if a key switch at the radio is depressed before a start of a time slot in which the radio can transmit, playing an audible signal as a hold-off tone at the radio and informing an operator that the radio must wait before transmitting, and when a next time slot arrives in which the radio can transmit, the audible signal is removed and the radio starts to transmit, and if a key switch is depressed after a start of the time slot, then waiting for a start of a next time slot to transmit. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A method for communicating digital voice, which comprises:
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receiving within a radio a non-packetized digital voice communications signal over a CSMA wireless communications channel as single channel, all-informed communications among a plurality of radios in a CSMA wireless communications network; dividing the period following the end of a received transmission into a sequence of time slots; in each time slot, deciding randomly or pseudo-randomly with probability p whether to start transmitting on the channel in that slot, provided that a new transmission has not been detected on the channel prior to the start of the slot; inferring whether collisions are likely from patterns in a temporal sequence of past transmissions on a communications channel; determining whether to apply p-persistence on each occasion on which a voice transmission ends and a communications channel becomes free; and applying p-persistence only when collisions are likely to occur so as to reduce overhead during transmission scenarios when collisions are unlikely.
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31. A method for communicating digital voice, which comprises:
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receiving within a radio a non-packetized digital voice communications signal over a CSMA wireless communications channel as single channel, all-informed communications among a plurality of radios in a CSMA wireless communications network; dividing the period following the end of a received transmission into a sequence of time slots; in each time slot, deciding randomly or pseudo-randomly with probability p whether to start transmitting on the channel in that slot, provided that a new transmission has not been detected on the channel prior to the start of the slot; and processing information within a transmission to determine if a collision is likely to occur, and if so, applying p-persistence.
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32. A method for communicating digital voice, which comprises:
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receiving within a radio a non-packetized digital voice communications over a CSMA wireless communications channel as single channel, all-informed communications among a plurality of radios in a CSMA wireless communications network; determining at the radio the start time of a sequence of transmit time slots; determining which of the transmit time slots in the sequence of transmit time slots is a first slot in which the radio can transmit; and if a key switch at the radio is depressed before a start of a time slot in which the radio can transmit, playing an audible signal as a hold-off tone at the radio and informing an operator that the radio must wait before transmitting, and when a next time slot arrives in which the radio can transmit, the audible signal is removed and the radio starts to transmit, and if a key switch is depressed after a start of the time slot, then waiting for a start of a next time slot to transmit; and inferring whether collisions are likely from patterns in a temporal sequence of past transmissions on a communications channel, and applying p-persistence only when such patterns indicate that collisions would otherwise be likely to occur.
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Specification