adaptive_power.m

OFDM的详细仿真代码

function [Cn,P]=adaptive_power(H,Ber0,N,Noise,R)

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 函数功能：
% 自适应调制和功率优化分配
% 基于功率梯度最小的QAM 算法

% 输入：
% Noise:噪声功率
% N:子载波的个数
% H:通过信道估计得到信道参数向量
% Ber0: 为系统需要的误码率
% R:固定比特速率

% 输出：
% Cn:分配给各子载波的比特数 Cn={0,2,4,6}
% P:分配给各子载波的功率
% 由QAM调制的误比特率公式得：
% 信噪比 SNR=In(5*Ber0)*(2^Cn-1)/(-1.6)
% 信噪比因子para

% 作者：郭莹，2004.3.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


para=log(5*Ber0)/(-1.6);
%初始化比特Cn,和功率P
Cn=zeros(N,1);
P=zeros(N,1);
% delta_P用于存储功率增量
delta_P=zeros(N,1);
%步长, 因为是使用QAM调制 
Step=2;
for yy=1:R/Step
   for i=1:N
        if Cn(i)>6
            delta_P(i)=inf;
        continue;
        end
   %y=H(i)^2;
    y = H(i).*conj(H(i));
   delta_P(i)=3*para*(2^(Cn(i)+Step)-2^Cn(i))*Noise/y;
  end
  dex=find(delta_P==min(delta_P));

  Cn(dex) = Cn(dex) + Step;
  
  P(dex)=P(dex)+delta_P(dex);
end
P(find(P==0))=1;