(i) at least one signal comprising control channel information is broadcast on a carrier to subscribers within the cellular radio communications system; (ii) the said carrier is divided into TDMA frames, each TDMA frame having a frame number (N); (iii) the system is adapted to store at least two sets (S0-S2) of pre-determined frequencies (f i ), the said carrier being broadcast at any particular time on a frequency taken from a selected one of the said sets (S0-S2) of pre-determined frequencies (f i ); (iv) the system is adapted to chose the said selected one of the said sets of pre-determined frequencies (f i ) in dependence on the frame number (N) of the TDMA frame being broadcast at the said time.
The invention allows the radio system to employ both frequency hopping and multi-slot transmission, for example in an EDGE compact GSM system.