get_rx_signal.m

一个UWB仿真程序包

%
%
%
function [pkts, rx_sig] = get_rx_signal(start_sample,...
stop_sample,pkts,packet_len,users,ep,symbol_start,TC,FS_CONT,...
channel_p,DATA_LENGTH,RSCODE,L,...
PACKET_LENGTH,BURST_LENGTH,SYMBOL_LENGTH,RX_BW,noise_var,samples,PLOT_DEBUG)

%check which packets are active in the piece of rx signal we are looking at
num_packets = length(pkts);
rx_sig = zeros(1,stop_sample-start_sample+1);
for i = 1:num_packets
%    start_sample
%    stop_sample
   first_idx_pkt = start_sample - pkts(i).start + 1;
   last_idx_pkt = stop_sample - pkts(i).start + 1;
   
   if(~(first_idx_pkt > packet_len || last_idx_pkt < 1)) %make sure this is not true: packet ends before we start or starts after end
       
       rs = RSCODE;
       dl = DATA_LENGTH;
       if(RSCODE && ~(pkts(i).user == 1))%coding of non uoi packets is
           %a waste of time, so don't do it...
           rs = 0;
           dl = PACKET_LENGTH;
       end
       
       %check whether we already have a channel for this one
       if(isempty(pkts(i).channel))
           %get the channel
           [norm_channel, pkts(i).ch_len] = get_compound_channel(TC,FS_CONT,...
                channel_p,PLOT_DEBUG);
            pwr_db = users(pkts(i).user).pwr;
            pwr_lin = 10^(pwr_db/10);
            pkts(i).channel = norm_channel .* sqrt(pwr_lin);
       end
       
%        %check whether we have a ths for this packet
%        if(isempty(pkts(i).ths))
%           if(~ep.rand_ths)%use the one from 802.15.4a
%               pkts(i).ths = ep.ths;
%           else %use a random THS
%               fprintf('random ths\n');
%               NHOP = SYMBOL_LENGTH/BURST_LENGTH/4;
%               pkts(i).ths = floor(NHOP*rand(1,PACKET_LENGTH));
%           end
%        end
%        
       %check whether we have data
       if(isempty(pkts(i).tx_bits))
           % Get the data bit (coded or uncoded)
           [pkts(i).tx_bits,pkts(i).data_bits] = get_tx_bit(dl,rs,ep.interleaver_seed);
           
       end
       
       %create the packet chunk
       temp_start = max(1,first_idx_pkt);
       temp_stop = min(last_idx_pkt,packet_len);
       
       temp_sig = create_packet(temp_start,temp_stop,pkts(i).channel,...
           pkts(i).ch_len,channel_p.chip_span,pkts(i).tx_bits,users(pkts(i).user).ths,ep.scrambling,symbol_start,...
           users(pkts(i).user).code,...
           L,TC,FS_CONT,dl,rs,PACKET_LENGTH,BURST_LENGTH,...
           SYMBOL_LENGTH,samples,PLOT_DEBUG);
       %add to the signal
       starting_point = max(1,pkts(i).start - start_sample + 1);
       
%        len_rx = length(rx_sig)
%        len_temp = length(temp_sig)
%        last_index = starting_point+len_temp-1
       
       
       rx_sig(starting_point:starting_point+length(temp_sig)-1) = rx_sig(starting_point:starting_point+length(temp_sig)-1) + temp_sig;
   end
end

%add noise
rx_sig = rx_sig + get_noise(length(rx_sig),noise_var,samples.chip,TC,FS_CONT,RX_BW);
%in fact this is not 100% correct, as the noise is
%if we have overlapping blocks the overlapping part will not
%twice see the same noise!!!

% if(PLOT_DEBUG)
%     figure
%     plot(rx_sig,'r')
% end

return;