Warning: Ignoring extra legend entries

Hi! I need help.I am trying to display multiple graphs for totalSubcarriers = 64 ,256.I got the graphs, but the result not what i expected.plus I oso got this Warning: Ignoring extra legend entries.i am not sure whats wrong.is it the loops or something else?

 function paprOFDMA()

 dataType = 'Q-PSK'; % Modulation format.

 totalSubcarriers = [64 256 ]; % Number of total subcarriers.

 numSymbols = 16; % Data block size.

 Fs = 5e6; % System bandwidth.

 Ts = 1/Fs; % System sampling rate.

 Nos = 4; % Oversampling factor.

 Nsub = totalSubcarriers;

 numRuns = 1000; % Number of runs.

 papr = zeros(1,numRuns); % Initialize the PAPR results.

 for h = 1:length (Nsub);

 Fsub = [0:Nsub(h)-1]*Fs/Nsub(h); % Subcarrier spacing

 for n = 1:numRuns,

    % Generate random data.

    if dataType == 'Q-PSK'

        tmp = round(rand(numSymbols,2));

        tmp = tmp*2 - 1;

        data = (tmp(:,1) + j*tmp(:,2))/sqrt(2);

    elseif dataType == '16QAM'

        dataSet = [-3+3i -1+3i 1+3i 3+3i ...

            -3+i -1+i 1+i 3+i ...

            -3-i -1-i 1-i 3-i ...

            -3-3i -1-3i 1-3i 3-3i];

        dataSet = dataSet / sqrt(mean(abs(dataSet).^2));

        tmp = ceil(rand(numSymbols,1)*16);

        for k = 1:numSymbols,

            if tmp(k) == 0

                tmp(k) = 1;

            end

            data(k) = dataSet(tmp(k));

        end

        data = data.';

    end

    % Time range of the OFDM symbol.

    t = [0:Ts/Nos:Nsub(h)*Ts];

    % OFDM modulation.

    y = 0;

    for k = 1:numSymbols,

        y= y + data(k)*exp(j*2*pi*Fsub(k)*t);

    end

    % Calculate PAPR.

    papr(n) = 10*log10(max(abs(y).^2) / mean(abs(y).^2));

 end

 %Plot CCDF.

 [N,X] = hist(papr, 100);

 semilogy(X,1-cumsum(N)/max(cumsum(N)),'-d')

 grid on;

 legend ('N=64','N=256')

 hold all

 xlabel('papr, x dB')

 ylabel('ccdf')

 end

 % Save data.

 save paprOFDMA

Answer 1

[Wayne King]

You only have one plot on the figure.

[N,X] = hist(papr, 100);
semilogy(X,1-cumsum(N)/max(cumsum(N)),'-d')
grid on;

but then you try to to put on legend on as if you had two plots on the same graph.

That's why you get the warning.

[sarah]

Then how to make this part display multiple plots?

 %Plot CCDF.
 [N,X] = hist(papr, 100);
 semilogy(X,1-cumsum(N)/max(cumsum(N)),'-d')
 grid on;

[Matt Kindig]

Hi sarah,

Provided that you want all of the histograms to overlay each other, just add 'hold on' after the semilogy command, i.e.

 semilogy(X,1-cumsum(N)/max(cumsum(N)),'-d')
 grid on; hold on;