the variable ‘SyncUsedElements’ is related to the HARQ which is currently not completely implemented.
% randomize the UE assignement
UE_mapping_temp = UE_mapping_temp(randperm(size(UE_mapping_temp,1)),:);
randomizes the order of users over frequency where the first dimension of ‘UE_mapping_temp’ is the number of users to schedule. For example; there are 6 resource blocks (RBs) available (per slot) and 3 users to schedule, then each UE is assignes 2 RBs. The ‘randperm’ then randomizes which two RBs out of the 6 are asigned to which user.