Abstract: A controlled CSMA packet switching system of a non-persistent carrier type in which in the event of a channel being sensed busy, a new sensing point is scheduled at random in a dynamically determined time interval TS.sub.n where ##EQU1## where TS.sub.u is the scheduling time interval that maximizes the expected throughput when all the stations compete for the channel access, TS.sub.1 is the scheduling time interval that maximizes the expected throughput when two stations complete for the channel access, TS.sub.n-1 is a scheduling time interval determined in a preceding (n-1)th observation interval, G.sub.n-1 is the average offered load in the (n-1)th observation interval, and G.sub.o is a nominal average offered load. An estimation of the average offered load G.sub.n-1 is derived from an estimation of the average idle period length in the (n-1) observation interval.