in one aspect , the method of synchronising a communications device in a wireless communications network comprises receiving a beacon signal at a first frequency ; and receiving a data signal at a second frequency , the beacon signal being used to synchronise reception of the data signal . in another aspect , the method comprises transmitting a beacon signal at a first frequency and transmitting a data signal at a second frequency , the beacon signal being useable to synchronise reception of the data signal . the first frequency is substantially less than the second frequency such that the beacon signal experiences substantially different frequency - dependent propagation effects to the data signal .