The proposed compander is also configured to the same values of PAPR so that the BER and PSDs of the companded signals can be fairly compared.
In case of PLC, both the compander and decompander are simulated .
It can be seen that the proposed compander can efficiently trade between PAPR and BER, i.
This is because we have carefully designed both the compander and decompander.
Since amplitude calculation is common in all cases, only the arithmetic operations in the compander functions are considered.
Since there will always be a minimum amount of noise present in the signal even at very high SNR, the OFDM systems employing companders have a noise floor.
Now the compander is designed for each of the J subsets separately using the conditional distributions given in Eq.
If D is a measure of companding distortion for a certain companding function and all of the J companders have similar mathematical form, design specifications and constraints, then, by virtue of the law of total expectation, the over-all mean companding distortion remains same as for the fixed compander.
The adaptive compander will operate by first calculating the statistic S for the input OFDM symbol, then selecting its parameter values from the compander parameter set and then the selected function will transform the signal amplitudes.
In this section, the design methodology for adaptive compander is developed using the piecewise linear companding transform recently proposed in .
2 Problem Formulation in Adaptive Compander Design Framework
In addition to optimizing the compander performance for the given objectives and constraints, the incorporation of new parameters in the problem framework provides additional degrees of freedom in specifying the objectives and constraints as compared to the fixed companders.