function y=precoding(x_symb)
                                     % 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

                                     
pre_aSingleAntennaPort;
pre_spatialMultiplexing;
pre_transmitDiversity;
end;