Communications Blockset

AWGN Channel

The AWGN Channel library block simulates transmission over a noisy channel. Its Signal to noise ratio (Es/No) mode uses these quantities to determine the variance:

• E_s/N_o, the ratio of energy per symbol to noise power spectral density
• The input signal power
• The symbol period

The values for these parameters are chosen as follows:

• The Es/No parameter is computed from the workspace variables EbNodB and M. The conversion from bit energy to symbol energy reflects the fact that each symbol carries log2(M) bits of information.
• The signal power is 1 watt because the M-PSK Modulator Baseband block produces unit power signals.
• The symbol period of the channel is set to Tsym.

Gray Coded M-PSK Modulation

Gray Coded MPSK Demodulation