ofdm in power line communication simulation

Hie all, I am now doing the OFDM Simulation for Power Line Communication. I
have written a very simple code for OFDM and have the impulse response of
the power line channel. I am facing the problem that the BER of my result
are high and constant along the SNR. So I would like to know whether my
simulation is correct or not, and hope that someone can give me an advice
on the simulations. I am using BPSK modulation. When I remove the impulse
response and only inserting the awgn noise, the graph is nice. but if with
the impulse response, the BER will get distorted.

Here are the codes...hope anyone can help me in this. 
Thanks in advance.


% OFDM Simulation

% Power Line Chanel Parameters

% impulse response
imp = [0.1556 0.0416 0.0586 0.0889 0.0199 -0.0055 -0.0201 0.0020 0.0096
0.0141 0.0070 0.0055 0.0049]; 


% Setup Value

SNR = 1:1:20;
num_data = 1000;
fft_size = 128;
repeat = 10;
M = 2;  % BPSK

for i_snr = 1:1:length(SNR)
    
    snr = SNR(i_snr);
    total_ber = 0;
    
    for rep = 1:1:repeat
        
    data_in = floor(rand(1,1000)*M);    %randint(1,num_data);

    num_chunk = ceil(num_data/fft_size);
    num_zero = fft_size - rem(num_data,fft_size);

    if num_zero ~= fft_size % pad the data with zero
        for i = 1:1:num_zero
            data_in = [data_in 0];
        end
    end

    % modulation
    
    data_mod = pskmod(data_in,M);

    % serial to parallel
    
    data_chunk = zeros(num_chunk,fft_size);
    for i = 1:1:num_chunk
        data_chunk(i,:) = data_mod(1,((i-1)*fft_size + 1):(i*fft_size));
    end

    % IFFT
    data_ifft = ifft(data_chunk);

    % parallel to serial
    
    data_tx = zeros(1,(num_chunk*fft_size));
    for i = 1:1:num_chunk
        data_tx(1,(((i-1)*fft_size) + 1):(i*fft_size)) = data_ifft(i,:);
    end    

    % channel

    data_rx = filter(imp,1,data_tx)*1/imp(1);
    data_rx = awgn(data_rx,snr,'measured');

    % serial to parallel
    
    data_fft = zeros(num_chunk,fft_size);
    for i = 1:1:num_chunk
        data_fft(i,:) = data_rx(1,((i-1)*fft_size + 1):(i*fft_size));
    end

    % FFT
    
    data_dechunk = fft(data_fft);

    % parallel to serial
    
    data_out =  zeros(1,(num_chunk*fft_size));
    for i = 1:1:num_chunk
        data_out(1,(((i-1)*fft_size) + 1):(i*fft_size)) =
data_dechunk(i,:);
    end

    % demodulation
    data_out = pskdemod(data_out,M);

    % analysis
    total_ber = total_ber + symerr(data_in,data_out)/length(data_in);


    end
    
    % average ber
    ber(i_snr,1) = snr;
    ber(i_snr,2) =  total_ber/repeat;
    
end

% plotting the analysis

semilogy(ber(:,1),ber(:,2),'-r');
grid on;