QPSK Modulation and Demodulation in the presence of transmitter and channel impairments

A QPSK transmitter and a receiver incorporating practical impairments (AWGN, Adjacent Channel,etc).

The submitted code attempts to model a relatively practical QPSK transmitter consisting of a bit stream generator a pair of modulators, RF up-converters along with a raised cosine filter, a digital to analogue converter (DAC) and a non-linear RF power amplifier (RF PA). The model could be used to assess the impact of the DAC's quantization noise, non-linearity of the RF power amplifier and an adjacent carrier along with AWGN on the receiver's performance. In addition to these, a phase imbalance and a phase offset could be added to the receiver's local oscillators. Phase noise could also be added to the local oscillators as a further enhancement.
The transmitter modulates the constellation bits on the sine and cosine components of a carrier signal of frequency 'Fc'. The receiver recovers the symbols by multiplying the received signal with the sine and cosine components of the carrier and integrating the result over the symbol duration applying the trapezoidal rule to obtain the in-phase and quadrature components of the received QPSK symbol which are in turn used to identify the appropriate constellation point of the modulated data and further decoded to obtain the bitstream.
References:
i) Simulation of Digital Communication Systems with MATLAB by Mathuranathan Viswanathan
ii) QPSK Modulation and Demodulation by Salim
iii) MPSK simulation by JC.