Fixed deterministic post-backoff for 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 member station in the first wireless local area network cell a first contention-free session, the first contention-free session 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 member 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;
setting by the first member station a backoff timer to a fixed deterministic post-backoff delay, which has a value of Bkoff times a fixed number of idle time slots, the value of Bkoff being greater than a number of overlapping cells;
counting down the backoff timer by the first member station;
transmitting a second contention-free session by the first member station when the backoff timer expires; and
resetting the backoff timer to the value of Bkoff to start a new cycle.
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Accused Products
Abstract
A cyclic prioritized multiple access (CPMA) method is disclosed which includes Fixed Deterministic Post-Backoff. Fixed deterministic post-backoff reduces conflicts between access points of overlapping cells. Contention-free sessions (CFSs) can be generated, one from each overlapping cell. Each active access point engages in a fixed deterministic post-backoff. A fixed deterministic backoff delay (Bkoff times a fixed number of idle time slots) is used by all access points, with the value of Bkoff being greater than the number of overlapping cells. The Bkoff should be large enough to enable the traffic that needs to be accommodated by the channel. Each access point has a backoff timer that is counted down using the shortest interframe space possible, typically the Priority Interframe Space (PIFS). A contention-free session (CFS) is initiated when the backoff timer expires, and it is then reset to the value of Bkoff to start a new cycle. A cycle is measured in terms of idle time slots instead of a fixed time interval. Contention-based transmissions can be attempted by an access point or other stations in the cell using their assigned priority while the access point is counting down its backoff timer. A new access point can get started and resolve possible collisions by a small random backoff. Subsequent contention-free sessions (CFSs) will not conflict, given an existing sequence of non-conflicting CFSs, since the follower access point'"'"'s backoff delay exceeds that of the leader'"'"'s by at least one times the fixed number of idle time slots. In this manner, contention-free sessions can be conducted without interference in the first and second cells.
99 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 member station in the first wireless local area network cell a first contention-free session, the first contention-free session 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 member 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; setting by the first member station a backoff timer to a fixed deterministic post-backoff delay, which has a value of Bkoff times a fixed number of idle time slots, the value of Bkoff being greater than a number of overlapping cells; counting down the backoff timer by the first member station; transmitting a second contention-free session by the first member station when the backoff timer expires; and resetting the backoff timer to the value of Bkoff to start a new cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. 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 first contention-free session, the first contention-free session 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 backoff timer in the first access point station, which is set to a fixed deterministic post-backoff delay, which has a value of Bkoff times a fixed number of idle time slots, the value of Bkoff being greater than a number of overlapping cells; wherein the backoff timer counts down the fixed deterministic post-backoff delay; wherein the first access point station transmits another one of the first contention-free session when the backoff timer expires; and wherein the backoff timer resets the value of Bkoff to start a new cycle. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A non-transitory computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform 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 member station in the first wireless local area network cell a first contention-free session, the first contention-free session 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 member 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; setting by the first member station a backoff timer to a fixed deterministic post-backoff delay, which has a value of Bkoff times a fixed number of idle time slots, the value of Bkoff being greater than a number of overlapping cells; counting down the backoff timer by the first member station; transmitting another one of the first contention-free session by the first member station when the backoff timer expires; and resetting the backoff timer to the value of Bkoff to start a new cycle. - View Dependent Claims (20)
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Specification