Multiaccess communications over a slot-synchronized collision channel without feedback (CCw/oFB) is considered. In the CCw/oFB the sources do not transmit simultaneously and continuously over the channel but according to protocol signals with duty factors smaller than or equal to one. This model was proposed by Massey and Mathys  for determining the loss due to sharing a common channel without timesharing. In their model the users share a common communication resource but the lack of a common time reference prevents operation in timesharing mode. Each user makes his transmissions at times determined by a protocol signal that is independent of the data to be sent, so that the capacity is independent of the source. This model expresses a worst-case assumption that each user has a nonempty queue of messages awaiting transmission.