In order to improve the performance of physical channels in telecommunications systems using wire-free telecommunication between mobile and/or stationary transmitting/receiving appliances as a function of; the channel data transmission rate, the system environment, the system utilization and the distance between the transmitting/receiving appliances, such that no circuitry changes are required to the transmitters and/or receivers in the transmitting/receiving appliances, an air interface is proposed, in which the number of N.sub.PILOT bits, N.sub.TPC bits and N.sub.TFC1 bits are each variable, and in which, in particular during an active or passive telecommunications link between the mobile and/or stationary transmitting/receiving appliances in the telecommunications system, the number of N.sub.PILOT bits, N.sub.TPC bits and N.sub.TFC1 bits can each be varied and/or optimized adaptively by control means, such as by suitable "layer 2" or "layer 3" signaling ("layer 2/3" signaling) which takes place, for example, via the DPDCH channel.