cicinterpolator.m

OFDM系统仿真

%-------cic interpolation filter
%-------time   :2007-12-06
%-------name   : Wanyiping
%R ratio change factor
%M delay order of comb filter
%N cascade stages num.

function    data_out=cicinterpolator(data,R,M,N);

data_len=max(size(data));

for i=1:M
    ds(i,1)=data(i);
end
for i=M+1:data_len
    ds(i,1)=data(i)-data(i-M);
end

if N>1
    for j=2:N
        for k=1:M
            ds(k,j)=ds(k,j-1);
        end
        for i=M+1:data_len
            ds(i,j)=ds(i,j-1)-ds(i-M,j-1);
        end
    end
end

for i=1:data_len
    data_comb(i)=ds(i,N);
end
up_data=zeros(1,length(data_comb)*R);
for m=1:length(data_comb)
    up_data(1,m*R-1) = data_comb(m);
end

up_data_len=max(size(up_data));

s(1,1)=up_data(1);
for i=2:up_data_len
    s(i,1)=up_data(i)+s(i-1,1);
end

if N>1
    for j=2:N
        s(1,j)=s(1,j-1);
        for i=2:up_data_len
            s(i,j)=s(i,j-1)+s(i-1,j);
        end
    end
end

data_out = s(:,N);