Frame based BPSK modulation/demodulation with AWGN | applied electronics engineering


Frame based BPSK modulation/demodulation with AWGN

By Applied Electronics - Friday, March 10, 2017 No Comments
In the following we show frame based BPSK digital modulation and demodulation scheme using AWGN channel. This is the 14th tutorial on Modeling digital communication systems using Simulink.

In the previous tutorials we have been using sample based signals in BPSK communication system. This is indicated by single line in connecting various blocks in Simulink. See Modeling and Simulation of Gaussian Noise channel in Simulink or How to create sampled based signal in simulink where sampled based signal have been used. Simulink models where frame based signals have been used have double lines connecting the source of the framed signal and other blocks. You will see this shortly.

Depending upon the system to be modeled frame based signal have to be sometimes used. For example, RS232 signals can be considered as frame based. The ethernet/internet packets are also frame based and optical signals are also frame based. There are many different frame based communication used in telecommunication. See books like Error-Control Block Codes for Communications Engineers or Essentials of Modern Telecommunications Systems.

Using framed based signal is thus often necessary in modeling digital communication system. Other aspects of using framed based signals is that they simulate often faster because the signals are characterized as matrices. Also frame based modeling often uses multiplexed signals.

Now the simulink model for frame based BPSK digital communication system with BPSK modulator demodulator and AWGN channel is shown below.

To set the signal as frame based signal we have configure the random integer generator to frame based. See the following figure. The Samples per frame is 10, that is, each frame carries 10 symbols.

As you may have noticed, the line is double line indicating that the signal on the lines are frame based signals.

Now, except for the setting for frame based signal, the setting here are same as in previous sample based BPSK modeled system. That is, the symbol period and sample time both are 1s. The input signal power is 1. The run time is 100000s. The AWGN has seed of 67 with Eb/No as 3dB. The theoretical probability of error is 0.0229. The simulated BER is 0.02287.


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