walshhadmard.m

walsh code for cdma communication in 3G

% Program to generate Walsh-Hadamard codes.
% These codes are orthogonal codes and when used in synchronous CDMA
% produce zero interference between signal carried by same RF frequency.
clc
clear
code_length=32;             % length of each code word: you can change.
code=[-1 -1; -1 +1];        % Initialization: -1=0 and +1=1
[r1 c1]=size(code);
while r1<code_length 
    % loop#1: Copying the code matrix itself below for new code matrix
    for i=1:r1
        for j=1:c1
            code(i+r1,j)=code(i,j);
        end
    end
    % Loop#2: Copying the code matrix on right to itself for new matrix
    for j=1:c1
        for i=1:r1
            code(i,j+c1)=code(i,j);
        end
    end
    % Loop#3: Copying cojugate of code matrix for complentary diagonal part
    for i=1:r1
        for j=1:c1
            code(i+r1,j+c1)=-1*code(i,j);
        end
    end
    [r1 c1]=size(code);
end
% Checking mutual orthogonality of all rows
sum=0;
data=[];
rows=[];
for i=1:r1
    A=code(i,:);
    for j=1:r1
        B=code(j,:);
        for k=1:c1
            sum=sum+A(k)*B(k);
        end
        data=[data sum];
        sum=0;
    end
    count=0;
    for h=1:length(data)
        if data(h)>0
            count=count+1;
        end
    end
    data=[];
    if count<=1
        rows=[rows i];
    end
end
if length(rows)==r1
    fprintf('All rows are orthgnal with each other')
else 
    fprintf('Following given rows are orthognal with each other')
    rows
end