snr.m

来自「这是一个超宽带的源码」· M 代码 · 共 36 行

%
% [g,gp] = snr(p,H);
%
% calculates snr and grad of snr (if asked), in g and gp
%
% H(i,j)  - fading between source of link <i> and dst of link <j>
% p(i)    - power allocated to link <i>
%
% g(i)    - SNR at reception of link <i>
% gp(i,j) - gradient dg(i)/dp(j)
%


function [g,gp]=snr(p, H)

N = size(p,1);
g = zeros(N,1);

for i=1:N
    I = 1 + H(i,:)*p - H(i,i)*p(i);
    g(i) = H(i,i)*p(i) / I;
end

if nargout > 1
    gp = zeros(N,N);
    for i=1:N
        I = 1 + H(i,:)*p - H(i,i)*p(i);
        for j=1:N;
            if i == j
                gp(i,j) = H(i,i) / I;
            else
                gp(i,j) = - H(i,j) * H(i,i)*p(i) / I^2;
            end
        end
    end
end