function ofdm_symbol = ifft_cp_tx_blk(inp_symbol,num_subc,guard_interval)
%-----------------------------------------------------------
%每個(gè)傳輸模塊的IFFT和循環(huán)前綴
%-------------------------
%輸入： 
%   inp_symbol ----所有子載波的輸入符號(hào)
%   num_subc ----子載波數(shù)
%   guard_interval ----OFDM符號(hào)的保護(hù)間隔
%輸出： 
%   ofdm_symbol ----加入IFFT和保護(hù)前綴的OFDM符號(hào)
%----------------------------

ofdm_symbol = ifft(inp_symbol,num_subc);
if(guard_interval>length(ofdm_symbol))
    error('The guard interval is greater than the ofdm symbol duration');
end

%The guard symbol is the copy of the end of the ofdm symbol to the
%beginning of the ofdm symbol
guard_symbol = ofdm_symbol(end-guard_interval+1:end);

%Add the cyclic prefix to the ofdm symbol
ofdm_symbol = [guard_symbol ofdm_symbol];