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Phase-shift keying – Wikipedia, the free encyclopedia – Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal (the carrier wave)….

In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise ……

Discuss the derivation of symbol error rate for general QAM modulation. The Matlab script compares the theoretical and the simulated symbol error rate for 16/64/256 ……

M-QAM Modulation: In M-ASK modulation the information symbols (each k=log2(M) bit wide) are encoded into the amplitude of the sinusoidal carrier. In M-PSK modulation ……

The theoretical symbol error rate for QPSK (4-QAM) in additive white gaussian noise is derived and simulation plots using Matlab/Octave scripts show agreement with ……

I think your theoretical curve is wrong. At SNR=25, QPSK BER should be slightly above 10^-3. Your result matches that of BPSK see second graph in the link http://www ……