Reducing Peak to Average Power Ratio of OFDM by Using Selected Mapping Technique

In the last decade, wireless communications have become increasingly popular as powerful and costeffective platforms for mobile communications. According to the demand of wireless communications 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 tradeoff 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) most popular technique. However, high peak to average power ratio (PAPR) is a major drawback of this modulation technique. Because high peak reduces the power efficiency of the RF power amplifier at transmitter. 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 paper presents a Selected Mapping (SLM) technique for reducing the peak to average power ratio (PAPR) of OFDM .The proposed scheme overcomes the disadvantages of existing reduction techniques. Because of the scramble an input data block of the OFDM symbols and transmit one of them with the minimum PAPR, this scheme has the probability of incurring high PAPR can be reduced. Moreover, the proposed scheme does not suffer from the out-of-band power, spectral efficiency and the complexity of subcarriers.