Data bearing peak reduction carriers for OFDM systems

The use of peak reduction carriers (PRCs) for peak-to-average power ratio (PAPR) reduction has previously been shown to be effective. However the use of PRCs reduces transmission efficiency since a number of the subchannels are used specifically for peak reduction purposes. This paper proposes a technique to allow the PRCs to bear data symbols giving rise to an increase in transmission efficiency. The technique involves the use of a higher order modulation scheme to represent a lower order modulation symbol. By doing so, the allowable amplitude and phase of the PRCs will be constrained to lie within the constellation region representing the data symbol to be transmitted. An optimised modulation scheme is proposed for the PRCs with the aim of maintaining the overall BER of the system while increasing transmission efficiency.