function SymQAM=tx_QPSK_mod(BitTx)

% Input:  BitTx(1,N_Num)               Output:  SymQAM(1,Carrier_Num*OFDM_Symbol)

N_Num=length(BitTx);
SymQAMtmp=reshape(BitTx,2,N_Num/2).';
SymQAMtmptmp=bi2de(SymQAMtmp,2,'left-msb');
% 00->1+i,10->-1+i,01->1-i,11->-1-i,

QAMTable=[1+i,1-i,-1+i,-1-i];
SymQAM=QAMTable(SymQAMtmptmp+1);