Author : Dileep M D 1
Date of Publication :7th June 2016
Abstract: Efficiency of Orthogonal Frequency-Division Multiplexing (OFDM) system is improved by reducing the power consumed by its transmitter and also by improving the spectral efficiency. Power usage is reduced by reducing the PAPR of OFDM system and spectral efficiency is improved by Adaptive modulation and coding schemes (AMC). In OFDM system, transmission signals can have high peak values in the time domain since many subcarrier components are added via an inverse fast Fourier transformation (IFFT) operation. As a result, OFDM systems are known to have a high peak-to-average power ratio (PAPR) or Crest factor when compared to single-carrier systems. The high PAPR is one of the most detrimental aspects in an OFDM [2,3] system. High PAPR decreases the signal-to quantization noise ratio (SQNR) of the analog-digital convertor (ADC) and digitalanalog convertor (DAC) while degrading the efficiency of the power amplifier in the transmitter. PAPR problem is more of a concern in the uplink since the efficiency of the power amplifier is critical due to the limited battery power in a mobile terminal. The core idea of AMC is to dynamically change the modulation and coding plans dependent upon the channel conditions in order to enhance overall spectral efficiency. Here through Matlab simulations overall battery power usage reductions and improvement in data throughout are shown.
Reference :
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