| 摘要 |
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.
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