FPGA Central

I am currently testing OFDM using BPSK modulation using the FE
(convolutional coding), since my bits are random 0s and 1s and withou
using a quantiser or interleaver, the channel that is used for testing i
AWGN channel (non-frequency selective), I am not sure what BER I am suppos
to expect.
The convolutional parameters used:constraint length = 7
rate =1/2
the trackback length = 12
Decision type is soft with K=1, otherwise it wont work because i a
comparing binary outputs or hard decision

( I read somewhere that the trackback length must be 4 times th
constraint length) but I am not happy with the simulation results.
the performance of OFDM without convolutional encoder is the same as th
modulation scheme starting from 7e-3 at 0dB and 0.0564 and so on.


For convolutional i am getting:
BER of convolutional =

0.0771 0.0015 0.0007 0.0008 0.0009 0.0004 0.0007
0.0009 0.0004 0.0006 0.0008 0.0006 0.0007 0.0003
0.0006 0.000

Any one can help?

omcio wrote:

> I am currently testing OFDM using BPSK modulation using the FEC
> (convolutional coding), since my bits are random 0s and 1s and without
> using a quantiser or interleaver, the channel that is used for testing is
> AWGN channel (non-frequency selective),

In the other words, your case is not any different from a textbook case
of a single BPSK signal in the AWGN channel. Take it from there.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

On Jul 9, 10:37*am, "omcio" <om...@hotmail.com> wrote:
> I am currently testing OFDM using BPSK modulation using the FEC
> (convolutional coding), since my bits are random 0s and 1s and without
> using a quantiser or interleaver, the channel that is used for testing is
> AWGN channel (non-frequency selective), I am not sure what BER I am suppose
> to expect.
> The convolutional parameters used:constraint length = 7
> rate =1/2
> the trackback length = 12
> Decision type is soft with K=1, otherwise it wont work because i am
> comparing binary outputs or hard decision
>
> ( I read somewhere that the trackback length must be 4 times the
> constraint length) but I am not happy with the simulation results.
> the performance of OFDM without convolutional encoder is the same as the
> modulation scheme starting from 7e-3 at 0dB and 0.0564 and so on.
>
> For convolutional i am getting:
> BER of convolutional =
>
> 0.0771 * *0.0015 * *0.0007 * *0.0008 * *0.0009 * *0.0004 * *0.0007 *
> 0.0009 * *0.0004 * *0.0006 * *0.0008 * *0.0006 * *0.0007 * *0.0003 *
> 0.0006 * *0.000
>
> Any one can help?

Looks good to me, even if I have no idea what the heck are these
numbers you just posted. So sure, looks good. I like numbers
anyway.

Julius