y = awgn(x,snr) adds white Gaussian noise to the vector signal x. The scalar snr specifies the signal-to-noise ratio in decibels. If x is complex, then awgn adds complex noise. This syntax assumes that the power of x is 0 dBW.
y = awgn(x,snr,sigpower) is the same as the syntax above, except that sigpower is the power of x in dBW.
y = awgn(x,snr,'measured') is the same as y = awgn(x,snr), except that awgn measures the power of x before adding noise.
y = awgn(x,snr,sigpower,state) is the same as y = awgn(x,snr,sigpower), except that awgn first resets the state of the normal random number generator randn to the integer state.
y = awgn(x,snr,'measured',state) is the same as y = awgn(x,snr,'measured'), except that awgn first resets the state of normal random number generator randn to the integer state.