A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, the transmitter comprising frame builder circuitry configured to receive the payload data to be transmitted and to receive signalling information for use in detecting and recovering the payload data at a receiver, and to form the payload data into frames with the signalling information as a preamble to each of the frames for transmission. Modulator circuitry is configured to modulate one or more first OFDM symbols with the signalling information to form the preamble of each frame and to modulate one or more second OFDM symbols with the payload data to form post preamble waveform of each frame. Transmission circuitry is configured to transmit the one or more first OFDM symbols as a preamble and the second OFDM symbols as the post preamble waveform. The transmitter includes signature sequence circuitry configured to provide a transmitter identifier signature sequence, the transmitter identifier signature sequence being one of a set of signature sequences to represent one of a predetermined set of identifiers which identify the transmitter to a receiver, and a combiner configured to combine the transmitter identifier signature sequence with one or more of the first OFDM symbols of the preamble or one or more additional OFDM symbols of the preamble dedicated to carry the transmitter identifier. A receiver can therefore be configured to identify the one or more of the first OFDM symbols of the preamble or one or more additional OFDM symbols of the preamble dedicated to carry the transmitter identifier, and to identify the transmitter of the received signal from the transmitter identifier sequence.