function x2=generate_x2(numbits,channelname,Nid,Ns,Nidmbsf,nRNTI,q)
%                   x2(n+31)=(x2(n+3)+x2(n+2)+x(n+1)x2(n))mod2,shall be initialized with 
%                   Cinit=nRNTI*2^14+q*2^13+floor(Ns/2)*2^9+Nid     PDSCH 
%                   Cinit=floor(Ns/2)*2^9+N_idmbsf                  PMCH
%                   Cinit=Nid                                       PBCH
%                   Cinit=(floor(Ns/2)+1)*(2*N_id+1)*2^9+Nid        PCFICH
%                   Cinit=floor(Ns/2)*2^14+Nid                      PDCCH                 
%                  where the nRNTI,Ns,Nid  Nidmbsf  and q are given by high
%                  layer
%                  where  the channelname is  given by high layer.The channelname is defined by the type of channel,PDSCH is 1,PMCH is 2,
%                  PBCH is 3,PCFICH is 4, PDCCH is 5.
switch channelname
    case 1
        Cinit=nRNTI*2^14+q*2^13+floor(Ns/2)*2^9+Nid;
        x2=de2bi (Cinit,31);
    case 2
       Cinit=floor(Ns/2)*2^9+Nidmbsf;
        x2=de2bi (Cinit,31);
    case 3
        Cinit=Nid ;
        x2=de2bi (Cinit,31);
    case 4
        Cinit=(floor(Ns/2)+1)*(2*N_id+1)*2^9+Nid;
        x2=de2bi (Cinit,31);
    case 5
       Cinit=(floor(Ns/2)+1)*(2*Nid+1)*2^9+Nid;
        x2=de2bi (Cinit,31);
end
          for i=1:(1600+numbits-31)
    x2(i+31)=mod((x2(i+3)+x2(i+2)+x2(i+1)+x2(i)),2);
end