An Assigned-Slot Listen-Before-Transmission Protocol for a Multiaccess Data Channel

In the multiaccess protocol described in this paper, users are each assigned specific slots of time in which to listen to the channel and determine if the channel is busy or idle. If the channel is idle, a ready user may transmit a fixed length message, or packet; otherwise he must wait a random time and try again. When two or more users transmit simultaneously, none are successful and each must retry after a random time. Though we have considered random slot assignment in general, in this paper we treat only fixed assignment. An interesting special case is when only one user is assigned to each sensing slot. Then there can be no collision and none of the channel capacity is wasted on retransmissions; that is, the channel is conflictfree. Delay-throughput performance curves are presented and compared with some other current multiaccess schemes of interest. Stability considerations are also discussed.