BER vs SNR simulation doesn't generate the same theoretical output in Simulink

Hi,

I am trying to plot the BER vs SNR curve for BPSK modulation scheme using bertool. But when I am doing the pulse shaping using root raised cosine filter, my BER curve is generated as below.

My simulation model is given below

The AWGN channel parameter is shown below

Please help me out here.

Thanks in advance

Answer 1

[Abhinav Aravindan]

The Root Raised Cosine (RRC) Filter introduces a delay in the model. This can be corrected by setting the “Receive Delay” parameter of the “Error Rate Calculation” block to the value equal to the group delay introduced by the RRC block. The following documentation explains it in detail:

1. https://www.mathworks.com/help/releases/R2021b/dsp/ug/group-delay-estimation.html
2. https://www.mathworks.com/help/releases/R2021b/comm/ug/filter-using-simulink-raised-cosine-filter-blocks.html

Furthermore, I can see that the “Number of bits per symbol” is set to 10 in the “AWGN Channel” block while in the BPSK modulation, each symbol represents 1 bit of information. The above modifications should help simulate the BPSK scheme with the RRC filter.

Please find attached a modified version of the Simulink model which can be used in “bertool” to simulate and related documentation for your reference. The theoretical simulation can be done by feeding a custom MATLAB function in “bertool”. Please find attached below the related documentation for further reference.

https://www.mathworks.com/help/releases/R2021b/comm/ref/biterrorrateanalysis-app.html

https://www.mathworks.com/help/releases/R2021b/comm/ref/errorratecalculation.html

https://www.mathworks.com/help/releases/R2021b/comm/ug/awgn-channel.html

The following variables have to be initialized in the MATLAB Workspace before simulation.

EbNo = 0;

maxNumErrs = 100;

maxNumBits = 1e8;