Chapter 3Digital Communications BER Performance in AWGN (BPSK and QPSK)

3.1 BPSK and QPSK Error Rate Performance in AWGN

This chapter introduces several topics in Simulink utilizing binary Phase-Shift Keying (BPSK) and quaternary Phase-Shift Keying (QPSK) modulations. Specifically these topics include:

  • Construction of a Simulink model in simple steps
  • Available menu choices
  • Description of inputs and outputs in simulations
  • Sample and frame-based computations
  • Complex signal representations
  • BPSK bit error rate (BER) simulated and theoretical results
  • Comparison of additive white Gaussian noise (AWGN) and Gauss Simulink library blocks
  • QPSK symbol error rate performance
  • Fixed point error rate performance

3.2 Construction of a Simulink Model in Simple Steps

The BPSK simulation for computing the bit error rate (BER) will be developed in a sequence of steps as follows:

  • Begin with the simplest Simulink BPSK model in a back to back configuration with no additive noise and verify proper operation (step 1)
  • Add an AWGN block with very high Eb/No so that additive noise does not introduce errors and verify proper operation (step 2)
  • Add scopes at the output of the BPSK modulator and input to the BPSK demodulator and observe multiple errors when Eb/No = −10 dB (step 3)
  • Add an error rate calculation block and an associated display to produce an estimate of the BER at a specified Eb/No value (step 4)
  • Add an information block and display the signal and port data types (step 5)

Figure 3.1

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