Help with Eb/No and BER relationship for QPSK-Viterbi(DVB-S)

[clein]

dvb-s ber

Hello!

I need to simulate with Matlab a QPSK modulation using Viterbi Coding. I need to obtain the theoricals graphs of the Eb/No and BER relationship for differents code rates (in fact, I need to obtain the graphs for Eb/No and BER relationship for a DVB-S system).

From "Error Control Systems", Stephen B. Wicker I have that BER can be calculated for BPSK as follows:

Pbsk = (1/k)·Q(√2dfree Eb/No)

If for a QPSK we have that Pqpsk = (1-Pbsk)², I obtain that:

Pqpsk = (2/k)·Q(x)·( 1 - ½·(1/k)·Q(x) ) where x = √2·dfree·Eb/No

Well, if I try to calculate it with Matlab I don't obtain the values that are specified in ETSI EN 300 421, I obtain lesser values of BER.

I calulate it defining some values of Eb/No and using dfree values indicated in ETSI EN 300 41.

I would like to know what are the mistakes, if I'm in the correct way or if there is another way to solve it.

Thanks!

 

[clein]

qpsk viterbi

If somebody is interested in this item, I've found the answer in 'DVB Document A014 Rev. 1 March 1998' Annex G.11

The BER after Viterbi in the DVB-S is less or equal than:


Pb(Eb/No) ≤ 1/k * 1/2 * Σ (d = dfree, ∞) w(d) · erfc(√Rc·d·Eb/No)


where:

Rc = k/n (code rate)
w(d)≡weigth of d (see document).

 

[tmltanml]

Re: dvb-s ber

Dear Clein,
Could you email me your m. file for the DVBS simultation. I have done the similar in .mdl but thought it is easier to simulate in m file. i can send you my model if you are interested.

Looking for forward for your reply.

thanks.

Hello!

I need to simulate with Matlab a QPSK modulation using Viterbi Coding. I need to obtain the theoricals graphs of the Eb/No and BER relationship for differents code rates (in fact, I need to obtain the graphs for Eb/No and BER relationship for a DVB-S system).

From "Error Control Systems", Stephen B. Wicker I have that BER can be calculated for BPSK as follows:

Pbsk = (1/k)·Q(√2dfree Eb/No)

If for a QPSK we have that Pqpsk = (1-Pbsk)², I obtain that:

Pqpsk = (2/k)·Q(x)·( 1 - ½·(1/k)·Q(x) ) where x = √2·dfree·Eb/No

Well, if I try to calculate it with Matlab I don't obtain the values that are specified in ETSI EN 300 421, I obtain lesser values of BER.

I calulate it defining some values of Eb/No and using dfree values indicated in ETSI EN 300 41.

I would like to know what are the mistakes, if I'm in the correct way or if there is another way to solve it.

Thanks!