can you explain this code: %%% perf. as fynction of snr
clear all;
warning off;
%%------------Initialisation des variables -----------%%
Num\_iteration=1;%10^4
cpt=1;
%carrier Frequency
carrierFreq = 3e9; % 7GHz
%Paramètres pour le Canal de Rice
lightSpeed=physconst('LightSpeed');
wavelength=lightSpeed/carrierFreq;
SamplingRate=30.72e6;
alpha=2;
%Power transmitted en dbm
Pt\_bs=30; 
Pt\_bsL=1;
PtWattUE=0.199526;
kFactor=5;
%Valeur pour la génération des signaux de référence (PSS et DMRS)
N=2048; 
% nombre d'antenne
%M=4;
 M=100;
%Coordonnées de la BS 
%bsSelected=[100 190];
bsSelected=[0 0];
%Nombre des voisins 
v=2;
%valeurs du SNR
snrTab=-10:5:30;
%for coordinates generation
radius = 100;
rotation = 0;
%%------------Fin Initialisation des variables -----------%%
for snr=snrTab
 snrL=10^(snr/10);
 N0dB=PtWattUE/snrL;
 N0=10^(N0dB/10);
 sigma\_n=sqrt(N0dB/2);
 Pr=zeros(1,3);
 pathLoss=zeros(1,3);
 SubMetC=0;
 SubMetF=0;
 SubMetD=0;
 thetaTrueTab=zeros(1,Num\_iteration);
 theta\_estTab=zeros(1,Num\_iteration);
 Err\_dist=zeros(1,Num\_iteration);
 Err\_theta=zeros(1,Num\_iteration);
 Err\_coordinates=zeros(1,Num\_iteration);
 distEstimated=zeros(1,Num\_iteration);
 
 neighborMatrix=zeros(v);
 dtrueUE\_NR=zeros(1,v);
 dP\_BS=zeros(1,v);
 PrUE\_NR=zeros(1,v);
 deUE\_NR=zeros(1,v);
 Coordiante=zeros(1,2);
 for it=1:Num\_iteration
 %User Equipement position
 ue=randi(100,1,2);
 thetaTrue=atan(ue(2)/ue(1))
 positions=zeros(2);
 xout=[NaN NaN];
 %verifier ue appartient cellule
% checkPos=0;
% while(checkPos==0)
% ue=randi(190,1,2); 
% checkPos = inside\_bs(ue, radius, bsSelected, rotation);
% end
 %calcul de la distance true entre le ue et le neighbor
 dtrueUE\_BS=sqrt(ue(1)^2+ue(2)^2);
 %Neighbors positions
 
 while (isnan(xout(1)))
 for cm=1:v
 neighbor=randi(100,1,2);
 neighborMatrix(cm,1)=neighbor(1);
 neighborMatrix(cm,2)=neighbor(2);
 %calcul de la distance true entre le ue et le neighbor
 dtrueUE\_NR(cm)=sqrt((abs(ue(1)-neighborMatrix(cm,1)))^2 + ((abs(ue(2)-neighborMatrix(cm,2)))^2));
 %estimation de la distance entre le ue et le neighbor
 %Free Space Model Friis
 if (dtrueUE\_NR(cm)==0)
 dtrueUE\_NR(cm)=1;
 end 
 PrUE\_NR(cm)=PtWattUE\*((wavelength./(4\*pi\*dtrueUE\_NR(cm))).^alpha)/N0;
 deUE\_NR(cm)=sqrt(((PtWattUE)/PrUE\_NR(cm)))\*(wavelength/(4\*pi));
 end 
 %intersection des deux cercles
 [xout,yout] = circcirc(neighborMatrix(1,1),neighborMatrix(1,2),deUE\_NR(1),neighborMatrix(2,1),neighborMatrix(2,2),deUE\_NR(2));
 end
 positions(1,1)=xout(1);
 positions(1,2)=yout(1);
 positions(2,1)=xout(2);
 positions(2,2)=yout(2);
 %Estimation de theta1 et theta2
 ttrueNR\_BS=zeros(1,v);
 theta\_est=zeros(1,v);
 coor\_est=zeros(1,v);
 power\_est=zeros(1,v);
% ttrueNR\_BS(1)=atan(abs(positions(1,2)-bsSelected(2))/abs(positions(1,1)-bsSelected(1)));
% ttrueNR\_BS(2)=atan(abs(positions(2,2)-bsSelected(2))/abs(positions(2,1)-bsSelected(1)));
 
 ttrueNR\_BS(1)=atan(positions(1,2)/positions(1,1));
 ttrueNR\_BS(2)=atan(positions(2,2)/positions(2,1)); 
 dP\_BS(1)=sqrt(positions(1,1)^2+positions(1,2)^2);
 dP\_BS(2)=sqrt(positions(2,1)^2+positions(2,2)^2);

 %Beamforming autour de theta1 et theta2
 DmrsGenerated=generateDMRS(N);
 %chan2 = rice\_fading(kFactor,1,1);
 %DmrsRice=conv(chanRay,DmrsGenerated);
 chanRay=(1/sqrt(2))\*(randn(1,N)+1i\*randn(1,N));
 
 DmrsRay=DmrsGenerated.\*chanRay;
% DmrsRec=awgn(DmrsRice,snr,'measured');
 % DmrsRec=awgn(DmrsRay,snr,'measured');
% DmrsRec=awgn(DmrsGenerated,snr,'measured');
 DmrsRec=DmrsRay;
 % for mm=1:v
 %calcul de la entre la position possible et le BS
 if (abs(ttrueNR\_BS(1)-thetaTrue) < abs(ttrueNR\_BS(2)-thetaTrue))
 [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,DmrsRec,ttrueNR\_BS(1));
 else
 [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,zeros(1,N),ttrueNR\_BS(1));
 end
 
 theta\_est(1)= thetaEst; power\_est(1)=Max\_p;
 if (abs(ttrueNR\_BS(2)-thetaTrue)<abs(ttrueNR\_BS(1)-thetaTrue))
 [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,DmrsRec,ttrueNR\_BS(2));
 else
 [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,zeros(1,N),ttrueNR\_BS(2));
 end
 theta\_est(2)= thetaEst; power\_est(2)=Max\_p;

 % coor\_est(mm,1)=coordinate(1);
 % coor\_est(mm,2)=coordinate(2);
 % end
 [maxP,indexP]=max(power\_est);
 thetaEst=theta\_est(indexP)
 pause
 dP\_BS\_EST=dP\_BS(indexP);%sqrt(positions(indexP,1)^2+positions(indexP,2)^2)
 dP\_BS\_Real=sqrt(ue(1)^2+ue(2)^2);
 coordinate=[dP\_BS\_EST\*cos((thetaEst)) dP\_BS\_EST\*sin((thetaEst))];

 %
 
% distEstimated(it)=sqrt((abs(Coordiante(1)-bsSelected(1)))^2 + ((abs(Coordiante(2)-bsSelected(2)))^2))
 %%------------sauvegarde des parametres-----------%%
 theta\_estTab(it)=thetaEst; 
 Err\_dist(it)=abs(dP\_BS\_EST-dtrueUE\_BS);
 Err\_theta(it)=abs(thetaEst-thetaTrue);
 Err\_coordinates(it)=sqrt((abs(ue(1)-coordinate(1)))^2 + ((abs(ue(2)- coordinate(2)))^2));
 if Err\_coordinates(it)<=1
 SubMetC=SubMetC+1;
 end
 if Err\_dist(it)<=1
 SubMetD=SubMetD+1;
 end 
 end
% %Root mean squared error
% %Distance error
 MEAN\_Dist(cpt)=mean(Err\_dist);
 MSE\_Dist(cpt)=mean(Err\_dist.^2);
% %RMSE\_Dist(cpt)=sqrt(MSE\_Dist(cpt));
% %Theta error
 MEAN\_T(cpt)=mean(Err\_theta)
 MSE\_T(cpt)=mean(Err\_theta.^2)
% %RMSE\_T(cpt)=sqrt(MSE\_T(cpt));
% %Coordinates error
 MEAN\_Coo(cpt)=mean(Err\_coordinates);
 MSE\_Coo(cpt)=mean(Err\_coordinates.^2);
% %RMSE\_Coo(cpt)=sqrt(MSE\_Coo(cpt));
% %Probabilitty of submeter precision for :
% %Coarse Coordinates Estimate
 PSubMetC(cpt)=SubMetC/Num\_iteration;
% %fine Coordinates Estimate
% PSubMetF(cpt)=SubMetF/Num\_iteration;
% %fine Distance Estimate
 PSubMetD(cpt)=SubMetD/Num\_iteration;
 cpt=cpt+1;
end
이 코드를 설명해 주시겠습니까? %%% PERF. AS FINCTION OF SNR모두 지우기;경고 해제;%%------------변수 초기화 -----------%%Num\_iteration=1;%10^4cpt=1;반송파 주파수carrierFreq = 3e9; % 7GHz쌀 운하의 %파라미터lightSpeed=physconst('LightSpeed');파장=lightSpeed/carrierFreq;샘플링 속도=30.72e6;alpha=2;전송된 %전력 dbmPt\_bs=30; Pt\_bsL=1;PtWattUE=0.199526;kFactor=5;참조 신호 생성에 대한 %값(PSS 및 DMRS)N=2048; 안테나 번호%M=4; M=100;BS 코디네이트 %bsSelected=[100 190];bsSelected=[0 0];보이스 이름 v=2;SNR 값snrTab=-10:5:30;좌표 생성용반지름 = 100;회전 = 0;%%------------핀 변수 초기화 -----------%%for snr=snrTab snrL=10^(snr/10); N0dB=PtWattUE/snrL; N0=10^(N0dB/10); 시그마\_n=sqrt(N0dB/2); Pr=제로스(1,3); 경로 손실=제로스(1,3); SubMetC=0; SubMetF=0; SubMetD=0; thetaTrueTab=zeros(1,Num\_iteration); theta\_estTab=zeros(1,Num\_iteration); Err\_dist=zeros(1,Num\_iteration); Err\_theta=zeros(1,Num\_iteration); Err\_coordinates=zeros(1,Num\_iteration); distEstimated=zeros(1,Num\_iteration);  neighborMatrix=zeros(v); dtrue\_NR=zeros(1,v); dP\_BS=zeros(1,v); PrUE\_NR=zeros(1,v); deUE\_NR=zeros(1,v); 조정자=제로(1,2); for it=1:Num\_iteration 사용자 장비 위치 UE=란디(100,1,2); thetaTrue=atan(ue(2)/ue(1)) positions=제로(2); xout=[NaN NaN]; %검증자 ue 부속 셀룰레checkPos=0;% while(checkPos==0)% ue=randi(190,1,2); checkPos = inside\_bs(ue, radius, bsSelected, rotation);end ue와 이웃 사이의 실제 거리를 계산합니다. dtrue\_BS=sqrt(ue(1)^2+ue(2)^2); 이웃 위치  while (isnan(xout(1))) for cm=1:v neighbor=randi(100,1,2); neighborMatrix(cm,1)=neighbor(1); neighborMatrix(cm,2)=neighbor(2); ue와 이웃 사이의 참 거리 계산 dtrue\_NR(cm)=sqrt((abs(ue(1)-neighborMatrix(cm,1)))^2 + ((abs(ue(2)-neighborMatrix(cm,2)))^2)); 공간과 이웃 사이의 %거리 추정 자유 공간 모델 Friis if (dtrueUE\_NR(cm)==0) dtrUE\_NR(cm)=1; end  PrUE\_NR(cm)=PtWattUE\*((파장./(4\*pi\*dtrueUE\_NR(cm))).^알파)/N0; deUE\_NR(cm)=sqrt(((PtWattUE)/PrUE\_NR(cm)))\*(파장/(4\*pi)); end  두 원의 교차점 [xout,yout] = circcirc(neighborMatrix(1,1),neighborMatrix(1,2),deUE\_NR(1),neighborMatrix(2,1),neighborMatrix(2,2),deUE\_NR(2)); end positions(1,1)=xout(1); positions(1,2)=yout(1); positions(2,1)=xout(2); positions(2,2)=yout(2); 세타1 및 세타2 추정치 ttrueNR\_BS=제로(1,v); theta\_est=제로스(1,v); COOR\_EST=ZEROS(1,V); POWER\_EST=ZEROS(1,V);% ttrueNR\_BS(1)=atan(abs(positions(1,2)-bsSelected(2))/abs(positions(1,1)-bsSelected(1)));% ttrueNR\_BS(2)=atan(abs(positions(2,2)-bsSelected(2))/abs(positions(2,1)-bsSelected(1)));  ttrueNR\_BS(1)=atan(positions(1,2)/positions(1,1)); ttrueNR\_BS(2)=atan(positions(2,2)/positions(2,1));  dP\_BS(1)=sqrt(positions(1,1)^2+positions(1,2)^2); dP\_BS(2)=sqrt(positions(2,1)^2+positions(2,2)^2); 세타1 및 세타2 자동 빔포밍 DmrsGenerated=generateDMRS(N); 찬2 = 쌀\_페이딩(kFactor,1,1); DmrsRice=conv(chanRay,DmrsGenerated); chanRay=(1/sqrt(2))\*(randn(1,N)+1i\*randn(1,N));  DmrsRay=DmrsGenerated.\*chanRay;% DmrsRec=awgn(DmrsRice,snr,'measured'); % DmrsRec=awgn(DmrsRay,snr,'measured');% DmrsRec=awgn(DmrsGenerated,snr,'measured'); DmrsRec=DmrsRay; for mm=1:v 가능한 위치와 BS 사이의 %계산 if (abs(ttrueNR\_BS(1)-thetaTrue) < abs(ttrueNR\_BS(2)-thetaTrue)) [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,DmrsRec,ttrueNR\_BS(1)); else [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,zeros(1,N),ttrueNR\_BS(1)); end  theta\_est(1)= thetaEst; power\_est(1)=Max\_p; if (abs(ttrueNR\_BS(2)-thetaTrue)<abs(ttrueNR\_BS(1)-thetaTrue)) [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,DmrsRec,ttrueNR\_BS(2)); else [thetaEst,Max\_p]= beamformingNr(sigma\_n,N,M,zeros(1,N),ttrueNR\_BS(2)); end theta\_est(2)= thetaEst; power\_est(2)=Max\_p; coor\_est(mm,1)=coordinate(1); coor\_est(mm,2)=coordinate(2); end [maxP,indexP]=max(power\_est); thetaEst=theta\_est(indexP) pause dP\_BS\_EST=dP\_BS(indexP);%sqrt(positions(indexP,1)^2+positions(indexP,2)^2) dP\_BS\_Real=sqrt(ue(1)^2+ue(2)^2); coordinate=[dP\_BS\_EST\*cos((thetaEst)) dP\_BS\_EST\*sin((thetaEst))]; % distEstimated(it)=sqrt((abs(Coordiante(1)-bsSelected(1)))^2 + ((abs(Coordiante(2)-bsSelected(2)))^2)) %%------------변수 보호-----------%% theta\_estTab(it)=thetaEst;  Err\_dist(it)=abs(dP\_BS\_EST-dtrueUE\_BS); Err\_theta(it)=abs(thetaEst-thetaTrue); Err\_coordinates(it)=sqrt((abs(ue(1)-coordinate(1)))^2 + ((abs(ue(2)-coordinate(2)))^2)); if Err\_coordinates(it)<=1 SubMetC=SubMetC+1; end if Err\_dist(it)<=1 SubMetD=SubMetD+1; end  end% %근평균 제곱 오차% %거리 오차 MEAN\_Dist(cpt)=mean(Err\_dist); MSE\_Dist(cpt)=mea