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Comparison of Simulated and Theoretical BPSK BER

By Applied Electronics - Thursday, March 9, 2017 No Comments
This is the 12th simulink tutorial of Modeling digital communication systems using Simulink where we will compare the simulated and theortical BER for BPSK modulation/demodulated system.

This is the continuing part of the tutorial Determination of BPSK BER performance under AWGN. There we obtained the BER for 40dB AWGN channel. The BPSK simulink model which we used is reshown below.

Determination of BPSK BER performance under AWGN

Now we want to compare the BER performance obtained with the model above with the theoretical BER.

Before doing that, lets review the BPSK simulink model setting.

In our simulink model the signal is complex and sampled signal. The symbol period is 1s, the sampling time is 1s, the run time is 10,000s, the random integer seed is 37 and the input signal power is 1W. The AWGN channel was configured with AWGN random seed of 67, the γb is 4dB. For this setting there were 1270 errors in 10,000s. Hence the simulated BER was 0.0127.

It is note-while that as far as the setting for AWGN block goes, the signal to noise field can be set to any of the Es/No, Eb/No or SNR. This is because for BPSK, binary case, these are all the same.



 Now using the bertool available in Matlab we can compare the BER obtained from our BSPK model and the theoretical calculation. A graphical comparison is shown below.

This graph is obtained in simulink using the bertool where a range of Eb/No values is entered and both theoretical and simulated results can be plotted. As you can see the Simulated BER coincides with the Theoretical BER for most of the Eb/No ratio.

This BER plot is the graph of Probability of Error(Pb) vs the Eb/No ratio. The relation between them is given by the following equation,



So in this way you can compare the simulated and theoretical BER of BPSK digital modulation system. BER calculation is important in the field of communication such as WiMAX, cellular system and telecommunication. It allows us to compare different digital modulation scheme such as BPSK, QPSK, QAM and there are many others. We will see many of them in the upcoming tutorials. To learn more about error and error control see the book Download Error-Control Block Codes for Communications Engineers PDF ebook free. For more fundamental theory see Download Communication System by Simon Haykin and/or Wireless Digital Communications: Design and Theory.

In the next tutorial you will learn an alternative method for modeling BPSK modulation and demodulation using gaussian noise source.

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