error 'index exceeds matrix dimensions' MATLAB

Question

0 voti

k=128;
V=4;
QPSK_Set=[1 -1 1j -1j];
Phase_Set=[1 -1];
Choose=[1 1 1 1; 1 1 1 2; 1 1 2 1; 1 1 2 2; 1 2 1 1; 1 2 1 2; 1 2 2 1; 1 2 2 2; 2 1 1 1; 2 1 1 2; 2 1 2 1; 2 1 2 2; 2 2 1 1; 2 2 1 2; 2 2 2 1; 2 2 2 2];
Choose_Len=16;
Max_SYMBOLS=1e5;
PAPR_Orignal=zeros(1,MAX_SYMBOLS);
for   nSymbol=1:MAX_SYMBOLS
       Index=randi(1,K,length(QPSK_Set))+1;
       X=QPSK_Set(Index(1,:));
       x=ifft(X,[],2);%frequency domain signal
      %time domain signal
      Signal_Power0=abs(x.^2);
      Peak_Power0=max(Signal_Power0,[],2);
      Mean_Power0=mean(Signal_Power0,2);
      PAPR_Orignal(nSymbol)=10*log10(Peak_Power0./Mean_Power0):%Calculate PAPR
end
PAPR_PTS6=zeros(1,MAX_SYMBOLS);
for nSymbol=1:MAX_SYMBOLS
     Index6=randi(1,K,length(QPSK_Set))+1;
     X6=QPSK_Set(Index6(1,:));
     x6=ifft(X6,[],2);
     I6=length(X6);
     A6=zeros(V,K);
     for v=1:V
         A6(v,v:V:K)=X6(v:V:K);%Interweave
     end
     a6=ifft(A6,[],2);
     min_value6=10;
end