Modeling of Digital Communication Systems Using SIMULINK

Chapter 4Digital Communications BER Performance in AWGN (MPSK & QAM)

4.1 MPSK and QAM Error Rate Performance in AWGN

This chapter continues the development of Simulink models for coherent modulations including multi-phase PSK (MPSK) and quadrature amplitude modulation (QAM). Topics presented here are listed as follows:

• MPSK BER Performance (floating point)
• MPSK BER Performance (fixed point)
• QAM BER Performance
  • Average power
  • Peak power
  • Nonlinear amplifiers

4.2 MPSK Simulink Model

In MPSK, it is assumed that k information bits are assigned to M = 2^k equal-energy signals. As a specific example, Figure 4.1 displays the Simulink model for determining the symbol error rate (SER) and BER performance for MPSK modulation with k = 6 and M = 64.

Figure 4.1 MPSK Simulink Model with M = 64.

The parameters in the MPSK modulator block are displayed in Figure 4.2. Note that in this simulation the parameters M and k must be entered in the MATLAB command window prior to executing the model. Gray coding is stipulated as well. The AWGN block parameters are displayed in Figure 4.3.

Figure 4.2 MPSK Input Parameters.

Figure 4.3 AWGN Parameters for MPSK Simulation.

In the AWGN block, ...