Crest factor reduction for carrier aggregated OFDM systems

To achieve higher data rate as specified in LTE-Advanced, support of wider Bandwidths are required than the existing 20 MHz system bands. Carrier Aggregation is the technique deployed in LTE-A system that can extends system bandwidth up to 100 MHz which also increases the downlink spectral efficiency. N-x-OFDMA will be used as the downlink transmission scheme in LTE-A. The primary concern in carrier aggregation is the significant increase in PAPR of the time domain signal, to accommodate large peaks PA has to operate with sufficient power back-off which results in lower operating efficiency. We propose two stages of Noise Shaping process for reducing the PAPR of the carrier aggregated composite signal which is a transmitter- side processing technique and does not require any information at the receiver. This paper analyzes different PAPR scenarios using contiguous & non-contiguous frequency bands for carrier aggregation and the simulation result shows the performance improvement in PAPR of about 3 & 4dB respectively.