|
% NOTE : This code is based on the example in the Matlab document linked here. I modified the plotGrid() function for the visualization shown in this note.
carrier = nrCarrierConfig;
carrier.NSizeGrid = 4;
carrier.SubcarrierSpacing = 15;
carrier.NSlot = 1;
carrier.NFrame = 0;
csirs = nrCSIRSConfig;
csirs.CSIRSType = {'nzp'};
csirs.CSIRSPeriod = {[40 1]};
csirs.Density = {'three'};
csirs.RowNumber = [1];
csirs.SymbolLocations = {4};
csirs.SubcarrierLocations = {0};
csirs.NumRB = 4;
csirs.NID = 2;
powerCSIRS = 0;
sym = nrCSIRS(carrier,csirs);
csirsSym = sym*db2mag(powerCSIRS);
csirsInd = nrCSIRSIndices(carrier,csirs);
ports = max(csirs.NumCSIRSPorts); % Number of antenna ports
txGrid = nrResourceGrid(carrier,ports);
txGrid(csirsInd) = csirsSym;
RelativePortNo = 0; % 3000+RelativePortNo corresponds to p in TS 38.211 section 7.4.1.5.3
plotGrid(size(txGrid),csirsInd,csirsSym,RelativePortNo+1,ports);
function plotGrid(gridSize,csirsInd,csirsSym,gridIndex,NoOfPort)
figure()
cmap = colormap(gcf);
chpval = {20,2};
chpscale = 0.25*length(cmap); % Scaling factor
tempSym = csirsSym;
tempSym(tempSym ~= 0) = chpval{1}; % Replacing non-zero-power symbols
tempSym(tempSym == 0) = chpval{2}; % Replacing zero-power symbols
tempGrid = complex(zeros(gridSize));
tempGrid(csirsInd) = tempSym;
NoOfRsPerPort = length(csirsSym)/NoOfPort;
subplot(1,3,1);
hold on;
image(chpscale*tempGrid(:,:,gridIndex)); % Multiplied with scaling factor for better visualization
axis xy;
xlim([0.5 14.5]);
set(gca,'xtick',1:14);
set(gca,'xticklabel',{'0','1','2','3','4','5','6','7','8','9','10','11','12','13'});
ylim([0.5 48.5]);
set(gca,'ytick',[0 11 23 35 47]+1);
set(gca,'yticklabel',{'0','11','23','35','47'});
x = 1.5:1:14.5;
y = 1.5:1:48.5;
plot([x(:),x(:)],[0,48.5],'w-');
plot([0,14.5],[y(:),y(:)],'w-');
y = 0.5:12:48.5;
plot([0,14.5],[y(:),y(:)],'w-','LineWidth',2);
%grid();
names = {'NZP CSI-RS','ZP CSI-RS'};
clevels = chpscale*[chpval{:}];
N = length(clevels);
L = line(ones(N),ones(N),'LineWidth',8); % Generate lines
% Index the color map and associate the selected colors with the lines
set(L,{'color'},mat2cell(cmap( min(1+clevels,length(cmap) ),:),ones(1,N),3)); % Set the colors according to cmap
% Create legend
%legend(names{:});
title('Reource Grid : CSI-RS')
xlabel('OFDM Symbols');
ylabel('Subcarriers');
subplot(1,3,[2 3]);
hold on;
for y = 1:12
for x = 1:14
circle(x,y,0.5);
end
end
symEnd = (gridIndex-1)*48*14 + 48;
symIndexStart = (gridIndex-1)*NoOfRsPerPort+1;
symIndexEnd = symIndexStart + NoOfRsPerPort-1;
RePerGrid = 48*14;
for i = symIndexStart:symIndexEnd
vx1 = double(floor((csirsInd(i)-RePerGrid*(gridIndex-1))/48)+1);
vy1 = double(mod(csirsInd(i),48));
vx2 = vx1 + 0.5*real(csirsSym(i));
vy2 = vy1 + 0.5*imag(csirsSym(i));
if vy1 < 13
line([vx1 vx2],[vy1 vy2],'Color','red');
plot(vx2,vy2,'ro','MarkerFaceColor',[1 0 0],'MarkerSize',3);
end
tmpStr = sprintf("%d,%f,%f",csirsInd(i),vx1,vy1);
disp(tmpStr);
end
axis([0 15 0 13]);
set(gca,'xticklabel',[]);set(gca,'yticklabel',[]);
set(gca,'xtick',[]);set(gca,'ytick',[]);
set(gca,'fontsize',8);
daspect([1 1 1]);
box on;
title('CSI-RS value in the first PRB')
xlabel('OFDM Symbols');
ylabel('Subcarriers')
set(gcf, 'Position', [100 100 800 600]);
set(gcf,'color','w');
end
function circle(x,y,r)
t = linspace(0,2*pi,20);
plot(x+r*cos(t),y+r*sin(t),'k-');
end
|
