Modeling of Digital Communication Systems Using SIMULINK

Chapter 5Digital Communications BER Performance in AWGN (FSK and MSK)

5.1 FSK and MSK Error Rate Performance in AWGN

This chapter addresses constant envelope modulations including binary frequency-shift keying (BFSK), multiple frequency-shift keying (MFSK), offset QPSK (OQPSK) and bandwidth-efficient modulations, minimum-shift keying (MSK) and Gaussian minimum shift keying (GMSK). Specific results are presented for

• BFSK BER performance
• MFSK BER performance
• MSK, OQPSK, and GMSK BER performance
• MSK and GMSK power spectra

5.2 BFSK Simulink Model

A simulation to estimate the BER for BFSK with noncoherent detection in AWGN is shown in Figure 5.1.

Figure 5.1 Model for Simulation of BFSK BER in AWGN with Noncoherent Detection.

Specific input parameters are as follows:

• BFSK noncoherent detection
• Symbol period = 0.2 s
• Sample time = symbol period = 0.2 s
• Run time = 1500 s
• Bernoulli binary seed = 61
• Frame based with 1 sample/frame
• Frequency spacing = 200 Hz (±100 Hz tones)
• FSK mod/demod = 2000 samples/symbol (f_s = 10 kHz)
• Input signal power = 1 W
• RBW = 976.56 mHz (∼1 Hz)
• Receive and computation delay = 0
• AWGN with γ_b = 10 dB =>
  • simulated BER = 0.0032

The BFSK boundaries for each symbol are selected to have continuous phase. Since there are 2000 samples/symbol with a 0.2 s symbol duration, the sampling rate is 10 kHz and is well above the Nyquist rate for the 200 Hz tone ...