vickyuet
Member level 2
- Joined
- Oct 3, 2006
- Messages
- 50
- Helped
- 0
- Reputation
- 0
- Reaction score
- 0
- Trophy points
- 1,286
- Location
- pakistan
- Activity points
- 1,691
I have built an OFDM transceiver with rayleigh channel using standard PDP's Like EPA,EVA and ETU.The problem is I am getting very high BER even for BPSK i.e 50-60 % or higher bits in error.Scatterplotting confirms it.My OFDM transceiver blocks include:
---- Random Data -- Modulation(BPSK,QPSK,QAM) -- Serial2Parallel -- IFFT -- CyclicPrefix >>> Rayleigh Ch >>> Remove CP Data---FFT --- Par2Ser ---DeMod --- Sink Data.
I have used builtin matlab function to create Rayleigh channel passing standard PDP as parameter.
%Filtering for n-OFDM symbols & calculating CIR
Similarly at receiver,after FFT block,I just tried to use this CFR by dividing received symbol by CFR as
What I am getting is very high SNR and scattered constellation symbols.Rest of transceiver blocks are simple and all verified as bug free...Do let me how to improve it. How I could get improve BER? Any need of equalizer?Should a match filter would help?Thanks in advance.
NOTE:ONLY RAYLEIGH CHANNEL IS USED AWGN NOISE IS NOT ADDED AT ALL ...
---- Random Data -- Modulation(BPSK,QPSK,QAM) -- Serial2Parallel -- IFFT -- CyclicPrefix >>> Rayleigh Ch >>> Remove CP Data---FFT --- Par2Ser ---DeMod --- Sink Data.
I have used builtin matlab function to create Rayleigh channel passing standard PDP as parameter.
channelObj = rayleighchan(tSampling,fDoppler,tau_in_sec,pdb_in_dB);
channelObj.ResetBeforeFiltering=0; % channel remains static before filtering
%Filtering for n-OFDM symbols & calculating CIR
for symb=1:OFDMSymb
ofdm_td_rx_signal,symb) = filter(channelObj, ofdm_td_TXdata,symb));
channel_cir(tapIndices,symb)= (channelObj.PathGains).';
end
channel_cfr = fft(channel_cir,nCarrier); % freq. response from CIR
Similarly at receiver,after FFT block,I just tried to use this CFR by dividing received symbol by CFR as
fft_RXdata=fft_data./channel_cfr;
What I am getting is very high SNR and scattered constellation symbols.Rest of transceiver blocks are simple and all verified as bug free...Do let me how to improve it. How I could get improve BER? Any need of equalizer?Should a match filter would help?Thanks in advance.
NOTE:ONLY RAYLEIGH CHANNEL IS USED AWGN NOISE IS NOT ADDED AT ALL ...