reduction of papr in ofdm system

can any one explain concept of papr?
how papr is reduced by dht precoded matrix?
if we reduce papr will there be any information loss??
plz anser this??

Papr should be reduced to increase amplifiers efficiency. The lower papr, the better amplification you will get in the RF stage. Using precoded matrix is a good option if you have computational power enough.
Propoer papr reduction is not distorting your signal, and hence, no SNR degradation or information lossing should happen.

can any one upload the document on precoded papr reduction......

PAPR is nothing but Peak to Average Power Ratio. It's a very simple concept. The range over which the amplifiers are linear is very small usually. So if the peak value is very large compared to the average value of the power then the waveform will get distorted because the peak value will be amplified by some value which is different from the amplification value for the average power. In order to reduce this it is necessary that we should bring all the values closer so that all are amplified by the same value. This can be done in many ways. One such way is by using companding. Here the peak values are amplified by some factor before it is fed into the RF amplifier so that when the waveform come out of the RF amplifier it will not be distorted and will have the same shape as the original waveform.


Hope this helps.