Patent ID: 7245605

Claim:
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 access point 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 access point 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; coordinating by a second access point 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 access point 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; transmitting by said first access point station a preemptive peg packet when it has no data to transmit, to maintain the contiguity of its transmission timing position with respect to a timing position of said second contention-free sessions transmitted by said second access point station; and said preemptive peg packet preventing gaps to be left idle for longer than a distributed coordination function (DCF) interframe Space (DIFS); whereby other stations are prevented from using DCF contention to seize the channel, until said first and second access points have completed one contention-free session (CFS) per periodic cycle.