function y=precoding(x,A,v,P,q)
                                     % A is defined by us for the number of physical ports
                                     % q is the number of code words;
                                     % v is the number of layers
                                     % P is the number of antenna ports
                                     % d0 is the resulting in a block of
                                     % complex-valued modulation
numbits = 168;
M_symb = numbits / 2; % the number of complex-valued symbols after QPSK modulation 
M_pusch_sc = 12; % Scheduled bandwidth for uplink transmission, expressed as a number of subcarriers;
               % M_pusch_sc=M_pusch_RB*N_RB_sc;
               % N_RB_sc:Resource block size in the frequency domain expressed as a number of subcarriers;N_RB_sc=12; 
               % M_pusch_RB represents the bandwidth of the PUSCH in terms of resource blocks,range from 1 to 100;
M_symb = length(d_symb);
% N = floor(M_symb / M_pusch_sc); % divide modulated symbols into (M_symb/M_pusch_sc) sets;each corresponding to one SC-FDMA symbol.
% d_symb_temp = reshape(d_symb,M_pusch_sc,N);% reshape d_symb(1,M_symb) into d_symb_temp(M_pusch_sc,N)
% z_temp = zeros(M_pusch_sc,N); % set z_temp(M_pusch_sc,N)=0
% for ii = 1:N                  % ifft transforming                                            
%      z_temp(:,ii)=(M_pusch_sc.^(-0.5)) * fft(d_symb_temp(:,ii),M_pusch_sc);
% end
% z_out = reshape(z_temp,1,M_symb); % reshape z_temp(M_pusch_sc,N) into z_out(1,M_symb)
  if  A==1                                    
   y=pre_aSingleAntennaPort(x);
  elseif A==2 
   y=pre_spatialMultiplexing(x);
  else A==3
   y=pre_transmitDiversity(x);
  end