A cellular communication system comprises a management function having a broadcast mode function; a plurality of wireless serving communication units operably coupled to the management function; and a plurality of wireless subscriber communication units receiving signals from respective wireless serving communication units in an uni-cast mode of operation on a frequency channel comprising a plurality of downlink transmission resources. The broadcast mode function applies a common cell identifier associated with broadcast transmissions from the plurality of wireless serving communication units thereby signalling to the plurality of wireless subscriber communication units that part or all of the transmission resource is to be configured or re-configured for broadcast mode of operation.