Staggered startup for cyclic prioritized multiple access (CPMA) contention-free sessions
First Claim
1. A method for reducing interference between overlapping first and second wireless LAN cells in a medium, each cell including a respective plurality of member stations, comprising:
- coordinating by a first member station in the first cell a periodic sequence of first contention-free sessions, each said session including multiple bursts with other member stations in the first cell, and retaining control of the medium by said first member station by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session;
listening by a second member station in the second cell to said activity in the medium and detecting an end to one of said first contention-free sessions indicated by an interval longer than a PIFS idle interval following an end to said activity in the medium;
setting a post-backoff delay by said second member station to periodically transmit a minimal interval after said first contention-free sessions of said first member station; and
coordinating by said second member station in the second cell a periodic sequence of second contention-free sessions, each said session including multiple bursts with other member stations in the second cell, and retaining control of the medium by said second member station by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session.
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Abstract
A staggered startup method and system for a cyclic prioritized multiple access (CPMA) system reduce interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations. A first member station in the first cell coordinates a periodic sequence of first contention-free sessions. Each contention-free session includes multiple bursts with other member stations in the first cell. The first member station retains control of the medium by using interframe spaces sufficiently short between the bursts so that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session. A second member station in the second cell listens to the activity in the medium and detects an end to one of the first contention-free sessions indicated by an interval longer than a PIFS idle interval following an end to the activity in the medium. The second member station then sets a post-backoff delay to periodically transmit a minimal interval after the first contention-free sessions of the first member station. The second member station coordinates in the second cell a periodic sequence of second contention-free sessions. In this manner, contention-free sessions are interleaved on a periodic basis in the first and second cells.
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Citations
10 Claims
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1. A method for reducing interference between overlapping first and second wireless LAN cells in a medium, each cell including a respective plurality of member stations, comprising:
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coordinating by a first member station in the first cell a periodic sequence of first contention-free sessions, each said session including multiple bursts with other member stations in the first cell, and retaining control of the medium by said first member station by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session; listening by a second member station in the second cell to said activity in the medium and detecting an end to one of said first contention-free sessions indicated by an interval longer than a PIFS idle interval following an end to said activity in the medium; setting a post-backoff delay by said second member station to periodically transmit a minimal interval after said first contention-free sessions of said first member station; and coordinating by said second member station in the second cell a periodic sequence of second contention-free sessions, each said session including multiple bursts with other member stations in the second cell, and retaining control of the medium by said second member station by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session. - View Dependent Claims (2, 3, 4, 5)
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6. A wireless communications system having reduced interference between overlapping first and second wireless LAN cells in a medium, each cell including a respective plurality of member stations, comprising:
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a first access point station in the first cell; said first access point station coordinating in the first cell a periodic sequence of first contention-free sessions, each said session including multiple bursts with other member stations in the first cell, and retaining control of the medium by said first access point by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session; a second access point station in the second cell; said second access point listening in the second cell to said activity in the medium and detecting an end to one of said first contention-free sessions indicated by an interval longer than a PIFS idle interval following an end to said activity in the medium; said second access point setting a post-backoff delay by to periodically transmit a minimal interval after said first contention-free sessions of said first access point; and said second access point coordinating in the second cell a periodic sequence of second contention-free sessions, each said session including multiple bursts with other member stations in the second cell, and retaining control of the medium by said second access point by using interframe spaces sufficiently short between the bursts that the multiple bursts appear to contending stations to be a single instance of activity in the medium during a session until an end of a session. - View Dependent Claims (7, 8, 9, 10)
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Specification