CCDF_PTS.m

function CCDF=CCDF_PTS(N,Nos,Nsb,b,dBs,Nblk)
% CCDF of PTS (Partial Transmit Sequence) technique.
% N    : Number of Subcarriers 
% Nos  : Oversampling factor
% Nsb  : Number of subblocks
% b    : Number of bits per QAM symbol
% dBs  : dB vector
% Nblk : Number of OFDM blocks for iteration

%MIMO-OFDM Wireless Communications with MATLAB¢ç   Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang
%2010 John Wiley & Sons (Asia) Pte Ltd

NNos=N*Nos;                       % FFT size
M=2^b; Es=1; A=sqrt(3/2/(M-1)*Es); % Normalization factor for M-QAM
mod_object=modem.qammod('M',M,'SymbolOrder','gray');
for iter=1:Nblk
   w = ones(1,Nsb);       % Phase (weight) factor
   mod_sym = A*modulate(mod_object,randint(1,N,M)); % 2^b-QAM
   [Nr,Nc] = size(mod_sym);
   zero_pad_sym = zeros(Nr,Nc*Nos);
   for k=1:Nr                       % zero padding for oversampling
      zero_pad_sym(k,1:Nos:Nc*Nos) = mod_sym(k,:);
   end
   sub_block=zeros(Nsb,NNos);
   for k=1:Nsb  % Eq.(7.27) Disjoint Subblock Mapping         
      kk = (k-1)*NNos/Nsb+1:k*NNos/Nsb;
      sub_block(k,kk) = zero_pad_sym(1,kk);
   end
   ifft_sym=ifft(sub_block.',NNos).';  % IFFT
   % --  Phase Factor Optimization  -- %
   for m=1:Nsb
      x = w(1:Nsb)*ifft_sym; % Eq.(7.27)
      sym_pow = abs(x).^2;
      PAPR = max(sym_pow)/mean(sym_pow); 
      if m==1, PAPR_min = PAPR;
       else if PAPR_min<PAPR, w(m)=1; else PAPR_min = PAPR; end
      end
      w(m+1)=-1; 
   end
   x_tilde = w(1:Nsb)*ifft_sym; % Eq.(7.29) : The lowest PAPR symbol
   sym_pow = abs(x_tilde).^2; % Symbol power
   PAPRs(iter) = max(sym_pow)/mean(sym_pow);
end
PAPRdBs=10*log10(PAPRs); % measure PAPR
dBcs = dBs + (dBs(2)-dBs(1))/2;   % dB midpoint vector
count=0;  N_bins=hist(PAPRdBs,dBcs);
for i=length(dBs):-1:1
   count=count+N_bins(i); CCDF(i)=count/Nblk;
end
plot_or_not = 0;
if plot_or_not>0
  figure(1), clf
  semilogy(dBs,CCDF,'-s'); axis([dBs([1 end]) 1e-4 1]); grid on; hold on
  title(['16 QAM CCDF of OFDMA PAPR, ',' ',num2str(N),'-point ' ,num2str(Nblk) '-blocks']);
  xlabel('PAPR_0 [dB]'); ylabel('Pr(PAPR>PAPR_0)'); 
end