mini slotted alternating priorities (MSAP)

Mini-Slotted Alternating Priorities (MSAP) is a collision-free multiple access method with reservation technique.

MSAP can be viewed as a call operation with carrier sensing and distributed control. The time axis is divided into smallest time slots, minislots, whose size is equal to or less than the propagation delay. In MSAP, connected stations are synchronized and begin their transmission at the start of the minislot. There is alternating priority control between stations, which provides equality for all stations.

MSAP's protocol scheme provides for a reservation preamble that is honored by all stations. There are several MSAP variants of the collision-free access scheme. An improved variant is Basic Bit-Map(BBM).