Peak To Average Power Ratio Reduction In Wireless Orthogonal Frequency Division Multiplexing
Loading...
Date
2014-02
Authors
Abdul Wahab, Aeizaal Azman
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Orthogonal Frequency Division Multiplexing (OFDM) offers an attractive multicarrier
technique with high spectral efficiency, simple implementation and robustness against multipath
fading. A trend of OFDM development is to increase the number of subcarriers to enhance
efficiency. However, when the number of subcarriers increases, certain time domain OFDM
coefficients are likely to acquire excessively large magnitudes. As such, the OFDM baseband
waveform is susceptible to high PAPR value and may suffer from non linear distortion at
subsequent power amplifier stage. This high PAPR can limit the transmitter power efficiency,
cause spectral spreading and reduce the bit-error-rate (BER) performance. To alleviate these
potential performance problems, two novel computationally efficient and low cost PAPR
reduction methods are proposed. The first method, called DCT-OFDM Method, seeks to apply
alternative structure for transmitting the high speed data in the OFDM system. The character of
the DCT energy focused is made use of in the frequency domain and it helps to reduce the PAPR
engendered by IFFT at the transmitter statistically, avoiding the nonlinear distortion in OFDM
systems due to great change of PAPR. It is mathematically verified that this method is potent to
reduce PAPR. Simulation results show that about 2.2 dB reduction in PAPR value is achieved by
this technique. Statistical Redistribution Method (SRM) which makes use of a non linear
companding operation is selected and applied on the OFDM outputs signals has been used as a
combination with Selected Mapping Method (SLM). The proposed scheme utilizes Selected
Mapping (SLM) followed by the companding SRM technique to further reduce the PAPR of the
OFDM signal. Simulation results indicate that about 5 dB reduction in PAPR is achieved
compared with the conventional SLM algorithm.
Description
Keywords
Power Ratio Reduction , Wireless Orthogonal Frequency