I’m trying to run the simulation with opt max throughtput in 3 MHz with with 5 users but it past a hour and the simulation didn’t even started yet. is this normal or does this mean that something is not right?
the ‘opt max Throughput’ scheduler maximizes the sum throughput over all possible schedules. This is done by exhaustive search over all possible user allocations. For a bandwidth of 5MHz and a number of 5 users, the number of possible schedules is quite huge and the simulation will need a lot of time (in the order weeks). To my experience the biggest simulation setup feasible on a PC is 3MHz of bandwidth and 3 users, and even that will take a lot of time (maybe days). However, the approximate maximum throughput scheduler also leads to good results.
thank you for quick response. I’ve ran the simulator in 1.4 MHz with 5 users and it lasted for about 19 hours. but I got results so I’m happy.
There is some other point I wanted to ask. In my simulations the opt. max throughput scheduler gives all the possible RBs to the first user the other users doesn’t get any RBs at all. Why does this scheduler gives all the RBs to one user?
I just checked with version 1.5. The ‘opt max throughput’ scheduler looks fine to me as it does not assign all resources only to one user. I think the effect you are referring to ist, that the curve for the user throughput shows zero throughput for all users except the first one at high SNR. This happens due to the implementation of the exhausitve search algorithm over all schedules. Once, a schedule with maximum throughput is found, and there is no other better schedule, it is taken as user assignment for the next transmission. At high SNR however, all users will be able to user CQI 15 in all resource blocks, meaning the maximum throughput is obtained if any user is assigned all RBs. The first schedule considered within the exhaustive search algorithm that does this, is the one where user 1 is assigned all resources.
This is our course not fair at all, but yields maximum throughput which is the ultimate goal of this schedulung algorithm. This scheduler does not consider fairnes at all. To improve fairnes at high SNR, one can add randomization for these high SNR cases.