matlab_OFDM系统的自适应功率和比特分配算法，实现系统资源的自适应分配

%----------------------Fischer Algo Perfect!------------------- %Programmed by xia %09-05-28 %----------------------------------------------------------- function [bit_alloc power_alloc]=Fischer(Num_subc,Rt,Pt,gain_subc) %------------------bit allocation ----------- N_H=1./gain_subc.^2; LD=log2(N_H); index_use0=1:Num_subc; %激活的子载波集合I初始化为{1：Num_subc} num_use=Num_subc; %激活的子载波数初始化等于Num_subc bit_temp0=(Rt+sum(LD))./Num_subc-LD; %集合I中的子载波初始比特分配 bit_temp=zeros(1,Num_subc); %比特调整前的临时变量 %------利用标志变量flag，实现do while语句------ flag=1; while flag id_remove=find(bit_temp0(index_use0)<=0); %返回需要移除的子载波序号在集合I中的位置，I中元素自动升序排列 index_remove=index_use0(id_remove); %返回移除的子载波序号，！关键一步，理解！～ if(length(index_remove)==0) %没有需要移除I中的子载波，跳出循环，进入比特round break; end index_use0=setdiff(index_use0,index_remove); %返回更新后的集合I num_use=length(index_use0); %更新后的I中可用子载波数目 bit_temp0(index_use0)=(Rt+sum(LD(index_use0)))./num_use-LD(index_use0); %在新的集合I中重新计算比特分配 flag=1; end index_use=index_use0; %将集合I（index_use0）中的激活子载波序号返回给变量index_use bit_temp(index_use)=bit_temp0(index_use); %将激活的子载波所分配的比特数返回给bit_temp,其他不可用子载波的比特分配都置为0 %-----------------bit round--------------------------- bit_round=zeros(1,Num_subc); bit_round(index_use)=round(bit_temp(index_use)); bit_diff(index_use)=bit_temp(index_use)-bit_round(index_use); bit_total=sum(bit_round(index_use)); %------------------bit alteration-------------------- while(bit_total>Rt) id_alter=find(bit_round(index_use)>0); %改动 index_alter=index_use(id_alter); %id_alter :index_use(子载波序号）的相对位置（顺序） min_diff=min(bit_diff(index_alter)); id_min=find(bit_diff(index_alter)==min_diff,1);%改动 index_min=index_alter(id_min);%改动 bit_round(index_min)=bit_round(index_min)-1; bit_total=bit_total-1; bit_diff(index_min)=bit_diff(index_min)+1; end while(bit_total<Rt) id_alter=find(bit_round(index_use)>0);%改动 index_alter=index_use(id_alter); %改动 max_diff=max(bit_diff(index_alter)); id_max=find(bit_diff(index_alter)==max_diff,1);%改动 index_max=index_alter(id_max);%改动 bit_round(index_max)=bit_round(index_max)+1; bit_total=bit_total+1; bit_diff(index_max)=bit_diff(index_max)-1; end %----------------bit allocation------------------ bit_alloc=bit_round; %------------------power allocation----------------------- power_alloc=zeros(1,Num_subc); %---------------改动：先找到最终的激活子载波集合----------------------- index_use2=find(bit_alloc>0); power_alloc(index_use2)=Pt.*(N_H(index_use2)).*2.^bit_round(index_use2)./... (sum(N_H(index_use2)).*2.^bit_round(index_use2)); %为激活子载波分配比特，不可用子载波发射功率都置为0 %-----------------EOF----------------------