www.gusucode.com > MIMO_OFDM系统的matlab仿真程序以及GUI界面的实现源码程序 > CH9/tx_gen_preamble.m
function preamble = tx_gen_preamble(SimulationParameters); global SimulationConstants; M=SimulationParameters.M; N=SimulationParameters.N; fft_length=SimulationParameters.FFTPoints; % generate the two long training symbols long_tr = SimulationConstants.LongTrainingSymbols; long_tr_symbol = tx_convert_to_time(long_tr,SimulationParameters); if ~SimulationParameters.TxDiv % single antenna preamble % extend with the 2*guard interval in front and then two long training symbols long_trs_signal = [long_tr_symbol(fft_length-2*16+1:fft_length) long_tr_symbol long_tr_symbol]; elseif SimulationParameters.TxDiv==2 % generate the two antenna preamble, % long training symbols are not transmitted simultaneously from both antennas to allow % channel estimation in receiver (orthogonal in time) long_trs_signal(1,:) = sqrt(2)*[long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol ... zeros(1,(fft_length+16))]; long_trs_signal(2,:) = sqrt(2)*[zeros(1,(fft_length+16)) ... long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol]; elseif SimulationParameters.TxDiv==4 long_trs_signal(1,:) = sqrt(4)*[long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol ... zeros(1,(fft_length+16)) zeros(1,(fft_length+16)) zeros(1,(fft_length+16))]; long_trs_signal(2,:) = sqrt(4)*[zeros(1,(fft_length+16)) ... long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol ... zeros(1,(fft_length+16)) zeros(1,(fft_length+16))]; long_trs_signal(3,:) = sqrt(4)*[zeros(1,(fft_length+16)) zeros(1,(fft_length+16)) ... long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol zeros(1,(fft_length+16))]; long_trs_signal(4,:) = sqrt(4)*[zeros(1,(fft_length+16)) zeros(1,(fft_length+16)) zeros(1,(fft_length+16)) ... long_tr_symbol(fft_length-16+1:fft_length) long_tr_symbol]; end % concatenate first short training symbols and long training symbols preamble(1,:) = [long_trs_signal(1,:)]; % add the second antenna preamble if SimulationParameters.TxDiv==2 preamble(2,:) = [long_trs_signal(2,:)]; elseif SimulationParameters.TxDiv==4 preamble(2,:) = [long_trs_signal(2,:)]; preamble(3,:) = [long_trs_signal(3,:)]; preamble(4,:) = [long_trs_signal(4,:)]; end