www.gusucode.com > ofdm结合2x2的m.. > ofdm结合2x2的m...构的WLAN环境数据传输仿真程序matlab版,包括信道估计和同步等模块/tx_gen_preamble.m
function preamble = tx_gen_preamble(sim_options); global sim_consts; %Generate first ten short training symbols short_tr = sim_consts.ShortTrainingSymbols; % generate four short training symbols short_tr_symbols = tx_freqd_to_timed(short_tr); % Pick one short training symbol Strs = short_tr_symbols(1:16); % extend to ten short training symbols short_trs=[Strs Strs Strs Strs Strs Strs Strs Strs Strs Strs]; short_trs_len=length(short_trs); % next generate the two long training symbols long_tr = sim_consts.LongTrainingSymbols; long_tr_symbol = tx_freqd_to_timed(long_tr); if ~sim_options.UseTxDiv % single antenna preamble % extend with the 2*guard interval in front and then two long training symbols long_trs_signal = [long_tr_symbol(64-2*16+1:64) long_tr_symbol long_tr_symbol]; else % generate the two antenna preamble, % long training symbols are not transmitted simultaneously from both antennas to allow % channel estimation in receiver long_trs_signal(1,:) = sqrt(2)*[long_tr_symbol(64-16+1:64) long_tr_symbol ... zeros(1,80)]; long_trs_signal(2,:) = sqrt(2)*[zeros(1,80) ... long_tr_symbol(64-16+1:64) long_tr_symbol]; end % concatenate first short training symbols and long training symbols preamble(1,:) = [short_trs(1,:) long_trs_signal(1,:)]; % add the second antenna preamble if sim_options.UseTxDiv preamble(2,:) = [short_trs(1,:) long_trs_signal(2,:)]; end