Contention protocols for wireless medium access in communication networks
First Claim
1. A method of controlling wireless medium access in a communication network having a number of terminals, comprising:
- defining one or more protocol message units for transmission by a given terminal which units correspond to an operational state of at least one of the terminal or the medium;
defining a minimum packet size that is at least the size of a smallest one of the protocol message units;
allocating a number of time slots for transmission of packets from the terminals, including defining each time slot to be of sufficient duration to contain the defined minimum packet size;
allocating within each time slot certain time periods corresponding to a number of contention opportunities; and
applying, at a given terminal and during the contention opportunities of each of the time slots, certain priority and backoff mechanisms so that packets are transmitted by the terminal within the time slots while (1) minimizing the occurrence of empty time slots during periods when packets are available at the terminal for transmission, and (2) minimizing the number of time slots during which two or more transmitted packets are detected simultaneously at the given terminal.
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Abstract
Wireless medium access in a communication network having a number of terminals is controlled by defining protocol message units for transmission by a given terminal which units correspond to operational states of at least one of the terminal and the medium. A number of time slots are allocated for transmission of packets from each terminal, and a number of contention opportunities are defined at the beginning of each time slot. Priority and backoff mechanisms are defined and applied at each terminal during the contention opportunities in the slots. Packets are then transmitted by the terminal within the slots while (1) minimizing the occurrence of empty slots at times when packets are available for transmission, and (2) minimizing the number of slots during which two or more packets are detected on the medium simultaneously at the terminal.
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Citations
25 Claims
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1. A method of controlling wireless medium access in a communication network having a number of terminals, comprising:
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defining one or more protocol message units for transmission by a given terminal which units correspond to an operational state of at least one of the terminal or the medium; defining a minimum packet size that is at least the size of a smallest one of the protocol message units; allocating a number of time slots for transmission of packets from the terminals, including defining each time slot to be of sufficient duration to contain the defined minimum packet size; allocating within each time slot certain time periods corresponding to a number of contention opportunities; and applying, at a given terminal and during the contention opportunities of each of the time slots, certain priority and backoff mechanisms so that packets are transmitted by the terminal within the time slots while (1) minimizing the occurrence of empty time slots during periods when packets are available at the terminal for transmission, and (2) minimizing the number of time slots during which two or more transmitted packets are detected simultaneously at the given terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of controlling wireless medium access in a S-CSMA protocol network having a number of terminals, including conducting a backoff procedure at a given terminal by;
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defining a contention window (CW); counting a number of backoff slots between packets transmitted on the medium and detected at the terminal; estimating a window occupancy (WO) value as a function of the CW and the counted backoff slots; detecting each transmission error (ER) that occurs on the medium; modifying the CW according to current values of WO and ER; and randomly selecting from the modified CW a backoff value corresponding to a number of contention opportunities over which the terminal backs off prior to transmitting available data. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification