wireless comunication system simulation

[matido]

wireless comunication

hi
i'm modeling a communication system(MB-OFDM UWB) in matlab,but i have no advanced knowledge on the digital communication simulation , i need to figure out the changes of SNR due to system modification so could you help me to build a system like:

convolution encoder(rates :1/3, 1/2, 3/4, 5/8 )+puncturing---->
block interleaver--->
QPSK modulation--->
(insert :channel est. sequence,pilots)IFFT--->channel--->
FFT(channel est.)--->
QPSK demod--->
deinterleaver--->
viterbi decoder

i have managed to build the QPSK modulator-demod,and figured out how to implement the OFDM ,BUT i need a block code of the encoder-decoder with puncturing and interleaver parts ,i have very limited time to finish the model.
has anyone experience on this subject?

Thank u for your attention .

 

[dhruva]

try mathwork.com

 

[chahd]

Re: wireless comunication

hi
i'm modeling a communication system(MB-OFDM UWB) in matlab,but i have no advanced knowledge on the digital communication simulation , i need to figure out the changes of SNR due to system modification so could you help me to build a system like:

convolution encoder(rates :1/3, 1/2, 3/4, 5/8 )+puncturing---->
block interleaver--->
QPSK modulation--->
(insert :channel est. sequence,pilots)IFFT--->channel--->
FFT(channel est.)--->
QPSK demod--->
deinterleaver--->
viterbi decoder

i have managed to build the QPSK modulator-demod,and figured out how to implement the OFDM ,BUT i need a block code of the encoder-decoder with puncturing and interleaver parts ,i have very limited time to finish the model.
has anyone experience on this subject?

Thank u for your attention .

Hello,
please i am also intrested in this topic , so please if you have any matlab code related to the MBOFDM please send it for me ,
my mail adress is:
b.bahja@yahoo.fr

 

[sib]

try to search these codes on "pudn". i am sure you can google it.

 

[muthukumar_ece2004]

%==========================================================================
% The mfile investigates the generation, transmission and reception of
% the OFDM signal without channel noise or HPA effect
%==========================================================================
clear all
clc
close
% ---------------
% A: Setting Parameters
% ---------------
M = 4; % QPSK signal constellation
no_of_data_points = 64; % have 64 data points
block_size = 8; % size of each ofdm block
cp_len = ceil(0.1*block_size); % length of cyclic prefix
no_of_ifft_points = block_size; % 8 points for the FFT/IFFT
no_of_fft_points = block_size;
% ---------------------------------------------
% B: % +++++ TRANSMITTER +++++
% ---------------------------------------------
% 1. Generate 1 x 64 vector of data points phase representations
data_source = randsrc(1, no_of_data_points, 0:M-1);
figure(1)
stem(data_source); grid on; xlabel('data points'); ylabel('transmitted data phase representation')
title('Transmitted Data "O"')
% 2. Perform QPSK modulation
qpsk_modulated_data = pskmod(data_source, M);
scatterplot(qpsk_modulated_data);title('qpsk modulated transmitted data')
% 3. Do IFFT on each block
% Make the serial stream a matrix where each column represents a pre-OFDM
% block (w/o cyclic prefixing)
% First: Find out the number of colums that will exist after reshaping
num_cols=length(qpsk_modulated_data)/block_size;
data_matrix = reshape(qpsk_modulated_data, block_size, num_cols);

% Second: Create empty matix to put the IFFT'd data
cp_start = block_size-cp_len;
cp_end = block_size;

% Third: Operate columnwise & do CP
for i=1:num_cols,
ifft_data_matrix,i) = ifft((data_matrix,i)),no_of_ifft_points);
% Compute and append Cyclic Prefix
for j=1:cp_len,
actual_cp(j,i) = ifft_data_matrix(j+cp_start,i);
end
% Append the CP to the existing block to create the actual OFDM block
ifft_data,i) = vertcat(actual_cp,i),ifft_data_matrix,i));
end

% 4. Convert to serial stream for transmission
[rows_ifft_data cols_ifft_data]=size(ifft_data);
len_ofdm_data = rows_ifft_data*cols_ifft_data;

% Actual OFDM signal to be transmitted
ofdm_signal = reshape(ifft_data, 1, len_ofdm_data);
figure(3)
plot(real(ofdm_signal)); xlabel('Time'); ylabel('Amplitude');
title('OFDM Signal');grid on;
% ------------------------------------------
% E: % +++++ RECEIVER +++++
% ------------------------------------------

% 1. Pass the ofdm signal through the channel
recvd_signal = ofdm_signal;

% 4. Convert Data back to "parallel" form to perform FFT
recvd_signal_matrix = reshape(recvd_signal,rows_ifft_data, cols_ifft_data);

% 5. Remove CP
recvd_signal_matrix(1:cp_len,=[];

% 6. Perform FFT
for i=1:cols_ifft_data,
% FFT
fft_data_matrix,i) = fft(recvd_signal_matrix,i),no_of_fft_points);
end

% 7. Convert to serial stream
recvd_serial_data = reshape(fft_data_matrix, 1,(block_size*num_cols));

% 8. Demodulate the data
qpsk_demodulated_data = pskdemod(recvd_serial_data,M);
scatterplot(qpsk_modulated_data);title('qpsk modulated received data')

figure(5)
stem(qpsk_demodulated_data,'rx');
grid on;xlabel('data points');ylabel('received data phase representation');title('Received Data "X"')

---------- Post added at 11:46 ---------- Previous post was at 11:44 ----------

for viterbi decoding, use virebi decoder Matlab command!