Preemptive packet for maintaining contiguity in cyclic prioritized multiple access (CPMA) contention-free sessions
First Claim
1. A method for reducing interference between overlapping first and second wireless local area network cells in a medium, each of the first and second wireless local area network cells including a respective plurality of member stations, comprising:
- coordinating by a first access point station in the first wireless local area network cell a periodic sequence of first contention-free sessions, each of the first contention-free sessions including multiple bursts with other member stations in the first wireless local area network cell, and retaining a control of the medium by the first access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium;
coordinating by a second access point station in the second wireless local area network cell a periodic sequence of second contention-free sessions, each of the second contention-free sessions including multiple bursts with other member stations in the second wireless local area network cell, and retaining the control of the medium by the second access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium;
transmitting by the first access point station a preemptive peg packet to maintain a contiguity of a transmission timing position of the first access point station with respect to a timing position of the second contention-free sessions transmitted by the second access point station; and
the preemptive peg packet preventing gaps to be left idle for longer than a distributed coordination function interframe space;
whereby other stations are prevented from using the distributed coordination function interframe space to seize the medium, until the first and second access point stations have completed one contention-free session per periodic cycle.
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Accused Products
Abstract
An access point transmits a preemptive peg packet when it has no data to transmit in order to maintain the contiguity of its transmission timing position with respect to the timing position of other contention-free sessions (CFS) transmitted by other access points in an existing, periodic sequence. The cyclic prioritized multiple access (CPMA) method establishes the transmission timing position of contention-free sessions (CFS) between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations. If an access point has no traffic, it will transmit a short, preemptive pegging packet and reset its backoff timer. In this manner, no gaps longer than the distributed coordination function (DCF) Interframe Space (DIFS) are left idle. This prevents other stations from using DCF contention to seize the channel, until all access points have completed one contention-free session (CFS) per periodic cycle.
101 Citations
20 Claims
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1. A method for reducing interference between overlapping first and second wireless local area network cells in a medium, each of the first and second wireless local area network cells including a respective plurality of member stations, comprising:
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coordinating by a first access point station in the first wireless local area network cell a periodic sequence of first contention-free sessions, each of the first contention-free sessions including multiple bursts with other member stations in the first wireless local area network cell, and retaining a control of the medium by the first access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium; coordinating by a second access point station in the second wireless local area network cell a periodic sequence of second contention-free sessions, each of the second contention-free sessions including multiple bursts with other member stations in the second wireless local area network cell, and retaining the control of the medium by the second access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium; transmitting by the first access point station a preemptive peg packet to maintain a contiguity of a transmission timing position of the first access point station with respect to a timing position of the second contention-free sessions transmitted by the second access point station; and the preemptive peg packet preventing gaps to be left idle for longer than a distributed coordination function interframe space; whereby other stations are prevented from using the distributed coordination function interframe space to seize the medium, until the first and second access point stations have completed one contention-free session per periodic cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A wireless communications system having reduced interference between overlapping first and second wireless local area network cells in a medium, each of the first and second wireless local area network cells including a respective plurality of member stations, comprising:
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a first access point station in the first wireless local area network cell, wherein the first access point station coordinates in the first wireless local area network cell a periodic sequence of first contention-free sessions, each of the first contention-free sessions including multiple bursts with other member stations in the first wireless local area network cell, and retaining a control of the medium by the first access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium; a second access point station in the second wireless local area network cell, wherein the second access point station coordinates in the second wireless local area network cell a periodic sequence of second contention-free sessions, each of the second contention-free sessions including multiple bursts with other member stations in the second wireless local area network cell, and retaining the control of the medium by the second access point station by using interframe spaces between the multiple bursts such that the multiple bursts appear to contending stations to be a single instance of activity in the medium; wherein the first access point station transmits a preemptive peg packet to maintain a contiguity of a transmission timing position of the first access point station with respect to a timing position of the second contention-free sessions transmitted by the second access point station; and wherein the preemptive peg packet prevents gaps to be left idle for longer than a distributed coordination function interframe space; whereby other stations are prevented from using the distributed coordination function interframe space contention to seize the medium, until the first and second access point stations have completed one contention-free session per periodic cycle. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification