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Article in DSPDesignLine.com: M-QAM symbol error

by Krishna Sankar on May 24, 2008

Its been a nice week for me, wherein I guest posted an article in DSPDesignLine.com. :)

The article derives the theoretical symbol error rate for M-QAM modulation. The theoretical results are further supplemented by Matlab/Octave simulation scripts.

Those who are familiar with derivation of symbol error rate for 16-QAM modulation will find the equations easy to interpret. As we did for 16-QAM,

(a) We identify the three different types of symbols – corner, inside, neither inside nor corner.

(b) Then we find the symbol error probability for each of the three types of symbols

(c) Total error probability is found assuming that all the symbols are equally likely.

Click here to read the article published in DSPDesignLine.com

The same article is cross-posted also in Embedded.com

For those who are not interested in the full article, the probability of error for M-QAM modulation is,

. :)

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Related posts

  1. Comparing BPSK, QPSK, 4PAM, 16QAM, 16PSK, 64QAM and 32PSK
  2. Symbol Error Rate (SER) for 16-QAM
  3. Comparing 16PSK vs 16QAM for symbol error rate
  4. Symbol Error Rate (SER) for QPSK (4-QAM) modulation
  5. Bit error rate for 16PSK modulation using Gray mapping

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{ 10 comments… read them below or add one }

1 neon March 13, 2009 at 2:38 pm

Hi,

Thanks for the dsplog, it really helps a lot.

I was wondering how this SER formula can be turned into BER vs EbNo formula, take 64-QAM for instance, i would use k = 1/sqrt(42), M = 64, and EsNo = 6*EbNo and then divide the whole formula by 6

Am I right?

thanks…

Reply

2 Krishna Pillai March 21, 2009 at 7:50 am

@neon: Thats correct. To be preceise, to divide the whole formula by 6, one needs to assume that each symbol error corresponds to only one bit error. For that to be true, one needs to assume Gray coded mapping. Which is a reasonable assumption.
You may look at the BER computation for 16-QAM with Gray mapping as an example:
http://www.dsplog.com/2008/06/05/16qam-bit-error-gray-mapping/

Hope this helps.

Reply

3 neon March 25, 2009 at 3:53 pm

yes it helps, thanks :)

Reply

4 ananta April 16, 2009 at 7:49 pm

Could you help me find matlab script for M-QAM that is used on OFDM?

Thank You

Reply

5 Krishna Pillai April 18, 2009 at 8:45 am

@ananta: If the channel is AWGN, the symbol error rate equation holds good for OFDM too. I have not posted code for M-QAM in OFDM case.

Reply

6 Krishna Pillai April 18, 2009 at 10:05 am

@ananta: You may find the M-QAM symbol error rate in AWGN simulation model @
http://www.dsplog.com/db-install/wp-content/uploads/2008/04/script_m_qam_ser.m

Reply

7 farrakh August 9, 2009 at 1:07 am

slam krishna
do u have bit error or symbol error simulations in nakagami_m channel.or related simulations with nakagami_m channel.
if u have plz email me.and plz email me ebook of bit error probability in awgn channel

thanks

Reply

8 Krishna Sankar August 11, 2009 at 4:41 am

@farrakh: Sorry, I have not discussed Nakagami fading in any posts till date.

Reply

9 Aditya December 8, 2009 at 10:10 am

Hi…
Thank you for this article…

I want to ask something about relation between SER and BER. To compute BER, i can use the formula :

BER = number of bit error / total bit

how about to compute SER? Is it similar formula like BER in simple way?
like :
SER = number of symbols error / total symbols

or another to compute SER ?

Thank you…

Reply

10 Krishna Sankar December 10, 2009 at 5:52 am

@Aditya: Your equation for symbol error rate is correct.

Reply

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