function demod_user_bit = demodulator( st_decoded, user_subc_alloc ,mod_subc ,pad_bit_cnt, AdptMod )   
                    
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% 解調,輸出經過判決的比特序列                  
% st_decoded, N_subc 行的向量


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demod_user_bit = [];
p = 1;
N_sym = size(st_decoded,2);
for n = 1:N_sym
      % 如果使用自適應調制,需要逐子載波進行解調

      if AdptMod == 1
          for k = 1:length(user_subc_alloc)
              subc_k = user_subc_alloc(k);   % 子載波號
              bit_k = mod_subc(k);           % 對應子載波的調制方式
              if bit_k ~= 0
                    %　取出符號,進行解調
                    bit_out = demodu_sym(st_decoded(subc_k,n),bit_k);
                    
                    demod_user_bit = [ demod_user_bit ; bit_out];
              end
          end
      else
          % 如果無自適應調制,可以把當前用戶在本OFDM符號中的所有子載波
          % 組成向量,送入解調器
          mod_type = mod_subc(1);       % 所有子載波調制方式相同
          bit_out = demodu_sym(st_decoded(user_subc_alloc,n).' , mod_type);
          demod_user_bit = [ demod_user_bit ; bit_out(:)]; % 轉為列向量
      end
end

demod_user_bit = demod_user_bit( 1: end - pad_bit_cnt );