PAPR reduction of OFDM signals using selected mapping technique

Abstract

According to the demand of advance communication field there should be high data rate in addition to both power efficiency and lower bit error rate.This demand of high data rate can be fulfilled by the single carrier modulation with compromising the trade off between the power efficiency and bit error rate. Again in the presence of frequency selective fading environment, it is very difficult to achieve high data rate for this single carrier modulation with a lower bit error rate performance. With considering an advance step towards the multi carrier modulation scheme it is possible to get high data rate in this multipath fading channel without degrading the bit error rate performance. To achieve better performance using multi carrier modulation we should make the subcarriers to be orthogonal to each other i.e. known as the Orthogonal Frequency Division Multiplexing (OFDM) technique.But the great disadvantage of the OFDM technique is its high Peak to Average Power Ratio (PAPR). As we are using the linear power amplifier at the transmitter side so it’s operating point will go to the saturation region due to the high PAPR which leads to in-band distortion and out-band radiation. This can be avoided with increasing the dynamic range of power amplifier which leads to high cost and high consumption of power at the base station.This report presents an efficient technique i.e the Selected Mapping which reduces the PAPR. Also the analysis of bit error rate performance and the computational complexity for this technique are being discussed here. In additions to the above analysis one important analysis of the mutual independence between the alternative OFDM signals generated using this technique, also being presented.One scheme proposed here which satisfies the PAPR reduction criteria with reducing the computational complexity. Also this new scheme has an important advantage of avoiding the extra bits along with the transmitted OFDM signal. This scheme can also be applied for the multiple transmitting antenna cases.