create_packet.m

一个UWB仿真程序包

function packet = create_packet(start_samples,stop_samples,compound_channel,...
    ch_len,chip_span,tx_bit,ths,scrambling,symbol_start,CODE_ID,L,TC,...
    FS_CONT,DATA_LENGTH,RSCODE,PACKET_LENGTH,BURST_LENGTH,SYMBOL_LENGTH,...
    samples,PLOT_DEBUG)


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%create preamble for user of interest
[uoi_pre sfd_code N_sync N_sfd] = generate_preamble(L,CODE_ID);
code_len = length(len31_preamble_code(CODE_ID));

%the packet chunk that will be output
packet = zeros(1,stop_samples-start_samples+1);

%calculate length of preamble in samples
pre_len_samples = (N_sync + N_sfd) * code_len * L * samples.chip; 

%check whether we need sth from data part
if(stop_samples<=pre_len_samples)
    %upsample, apply pulse shape and multipath channel
    [rx_uoi] = get_preamble_signal(uoi_pre,compound_channel,...
        ch_len, chip_span, TC,...
        FS_CONT,PLOT_DEBUG);
    packet(1:end)=rx_uoi(start_samples:stop_samples);
else
    temp_len = 0; %what we already have
    
    % Pre-construction of the data signal of interest
    [burst, burstlength] ...
        = condor_init_data_signal(FS_CONT, PACKET_LENGTH, ...
        TC,BURST_LENGTH,SYMBOL_LENGTH, ...
        ths, scrambling, samples, ...
        compound_channel);

    %first index into rx_data part
    start_idx = max(1,start_samples-pre_len_samples);
    
    % Get the data signal of interest
    [rx_data] ...
        = get_data_signal(PACKET_LENGTH, ...
        samples.burst, samples.symbol, burstlength, ...
        burst,ths,symbol_start,tx_bit);
    
    %do we also need sth from preamble ?
    if(start_samples <= pre_len_samples || start_idx < ch_len)
        %calculate preamble part
        %upsample, apply pulse shape and multipath channel
        [rx_uoi] = get_preamble_signal(uoi_pre,compound_channel,...
            ch_len, chip_span, TC,...
            FS_CONT,PLOT_DEBUG);
        %is a part of the packet from the preamble?
        if(start_samples <= pre_len_samples)
            %how much
            temp_len = length(rx_uoi)-(ch_len-1)-start_samples+1;
            packet(1:temp_len) = rx_uoi(start_samples:end-(ch_len-1));
        end
        %do we need the overlap?
        if(start_idx < ch_len)
            %keep the overlapping part of the preamble
            overlap = rx_uoi(end-(ch_len-1)+1:end);

            %now we have to add the overlap from the multipath channel
            rx_data(1:ch_len-1) = rx_data(1:ch_len-1) + overlap;
        end
        clear rx_uoi; %free memory
    end
    
    %cat the part we still need
%     start_idx
%     temp_len
%     start_idx + stop_samples - start_samples - temp_len
    packet(temp_len+1:end) = rx_data(start_idx:start_idx + stop_samples - start_samples - temp_len);

%     if(length(packet)~=stop_samples-start_samples+1)
%         error('error while creating packet...');
%     end

end