how the subcarrier allocation to users in a random manner

In the image given below rows represent 5 users and columns represent 20 subcarriers. each user needs to have atleast 3 or 4 subcarriers. If user one is using subcarrier 1,3,5 and 7 it should not be used by user 2,3,4 and 5. so it should be marked as 0. similar procedure needs to get repeated for all the users.

[KSSV]

YOu can have a look on fucntions ismember and intersect to get the common elements in different sets.

Answer 1

[KSSV]

a=[ 1 12  6 25 8 30
    10 9  3 20 4  9
     5 2 15  7 3  6] ;

used = sort([1 5 9 2 6 3 25 20 8 3 9 6]) ;
idx = ismember(a,used) ;
iwant = zeros(size(a)) ;
iwant(~idx) = a(~idx) ;

Answer 2

[Walter Roberson]

carrier_list = reshape( randperm(NumberOfSubcarriers), NumberOfUsers, [])

Now each column tells you which subcarriers one user is allocated.

For the case where the number of subcarriers is not an exact multiple of the number of users, then

num_extra = mod(NumberOfSubcarriers, NumberOfUsers);
baseNumber = NumberOfSubcarriers - num_extra;
carrier_list = reshape( randperm(baseNumber), NumberOfUsers), []);
carrier_list(end+1, randperm(NumberOfUsers, num_extra) ) = baseNumber+1 : NumbeOfSubcarries;

Now each column tells you which subcarriers one user is allocated, with 0 for no subcarrier (some users may have one more subcarrier than the others; the split is as even as possible.)