a method of spatial modulation and associated transmission apparatus , receiver apparatus , computer program product and system for identifying a transmitter element within a transmission array of at least two transmitter elements , wherein a signal is transmitted by one active transmitter element at a time over a channel to a receiver . power is allocated to the transmitter elements , wherein the power is allocated differently between at least two transmitter elements . the transmitted data is received at the receiver . the location of the active transmitter element is detected using knowledge of the power allocated to the transmitter elements .