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?
BER performance of BPSK OFDM in AWGN channels
Started by ●July 9, 2009
Reply by ●July 9, 20092009-07-09
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
Reply by ●July 9, 20092009-07-09
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