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BER Test Set in OFDM systems

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(joined September 2014)
Participant

Good day!

In OFDM systems, the BER Test Set component takes 5 OFDM parameters into consideration for calculating bit rate and bit-error-rate:

– number of fft points;
– number of subcarriers in each OFDM symbol;
– number of cyclic prefix points;
– number of training symbols;
– number of pilot symbols.

I would like to know how these parameters are taken into consideration for calculating error. After all, all of them have to be taken care of by OFDM components themselves, so the input to BER Test Set should be a bit sequence with bits supposedly the same as those produced for transmission.

Also, BER Test Set calculates bit rate as the bit rate defined in layout parameters multiplied by “no. subcarriers in each OFDM symbol/no. fft points”. Why doesn’t this component consider cyclic prefix (which has a temporal effect on signal), training and pilot symbols when calculating bit rate?

Thank you in advance.

Responses (5):

    • #54148
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      alistu
      Participant

      Good day!

      In OFDM systems, the BER Test Set component takes 5 OFDM parameters into consideration for calculating bit rate and bit-error-rate:

      – number of fft points;
      – number of subcarriers in each OFDM symbol;
      – number of cyclic prefix points;
      – number of training symbols;
      – number of pilot symbols.

      I would like to know how these parameters are taken into consideration for calculating error. After all, all of them have to be taken care of by OFDM components themselves, so the input to BER Test Set should be a bit sequence with bits supposedly the same as those produced for transmission.

      Also, BER Test Set calculates bit rate as the bit rate defined in layout parameters multiplied by “no. subcarriers in each OFDM symbol/no. fft points”. Why doesn’t this component consider cyclic prefix (which has a temporal effect on signal), training and pilot symbols when calculating bit rate?

      Thank you in advance.

    • #54202
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      Ahmad Atieh
      Participant

      Hello,
      All the information that you are asking about can be found in the BER Test Set datasheet that you may access it using right click on the visualizer, then choose “Component Properties…” and press the “? Help” button.
      Regards,
      Ahmad

    • #54214
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      alistu
      Participant

      Hi Ahmad,

      Thank you for your response. Regarding BER for OFDM, the help section only emphasizes in a few lines the importance of assigning the same values to the component as the ones used in OFDM transceivers with no other explanations on how the parameters are considered in calculations.

    • #59256
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      Kam
      Participant

      Hi Alistu. I also want answer to your question. did you find out?

    • #59263
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      Ahmad Atieh
      Participant

      Dear Alistu,
      The setting of these parameters is usually done by the designer. They affect the system performance and accuracy. The default values in the component is what is typically published. However, users can change them as needed in their system.
      The BER Test set needs to know the number of subcarrier to determine number of bits per subcarrier and to synchronized the received bits. This includes knowing if there are prefix, training and pilot symbols.
      There is no FFT points in BER Test Set.
      I recommend you refer to text book on OFDM for more information.

      regards,
      Ahmad

    • #59401
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      Kam
      Participant

      Thank you for replying Sir. Can you please refer a text book on ofdm for beginners like me?

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