Originally posted by: meletis13forever

I have a problem with my code in a mathematical problem.Here is my code:

range users=1..4;
range subcarrier=1..4;
range throughput=1..4;
int cuserssubcarrier=...;
int targetthroughput=...;

maximize
sum(i in users,k in subcarrier,t in throughput)
target[t]*c[i][k];

My code is working and i have also add external data but ILOG don't show me the values from the arrays it used to maximize the function.I must use decision variables(dvar) but i don't know how.I am confused.Can you help me please?
#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: meletis13forever

I have changed my code like this:
Here is the .mod file:
{string} Users=...;
tuple Userdata{
int SubcBR1;
int SubcBR2;
int SubcBR3;
int SubcBR4;
int TargetBR;
}
Userdata UserUsers=...;
dvar int+ UserSubcUsers;

maximize
sum(i in Users)
(User[i].SubcBR1 * UserSubc[i]+
User[i].SubcBR2 * UserSubc[i]+
User[i].SubcBR3 * UserSubc[i]+
User[i].SubcBR4 * UserSubc[i]) * ln(User[i].TargetBR);

subject to{
forall(i in Users)
UserSubc[i]<=User[i].TargetBR;
}
And here is the .dat file:
Users = { "user1", "user2", "user3", "user4" };
User = #[
user1 : < 64, 256, 128, 64, 256 >,
user2 : < 64, 64, 128, 128, 128 >,
user3 : < 256, 128, 64, 64, 256 >,
user4 : < 64, 256, 64, 128, 128 >
]#;

I want to write one more constraint in the .mod file.
One subcarrier can be assingned only on one user-the same subcarrier can not be assigned to two or more users.Can you help me?
#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: SystemAdmin

Dear Meletis,

at least to me your model an dwhat you would like to achieve with it is unclear.
What does that mean, that a user is assigned to a subcarrier? Does that mean,
to chosse one of the SubcBRx?
What impact does that choice have on your objective? So far,due to your
objective UserSubc[i] is set to value User[i].TargetBR. This value is multiplied
with each of the User[i].SubcBRx. Is that, what you have in mind with your objective?

Please provide some more information.

Best regards
Norbert
#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: meletis13forever

The problem is that we have an OFDM-based system which uses a technique that is called DSA(Dynamic Subcarrier Assignment).
We have 4 users and 4 subcarriers with data rates for each user.Each user have also an achievable data rate (TargetBR).Next we want to maximize the objective function that is:in all users, ln(achievable data-rate for user i)*(data rate of subcarrier that has been choosen for this user).Next we have the constraints that 1 subcarrier is used only from 1 user and have 1 data rate(The other data rates of the choosen subcarrier can not be used in the other users)
Example:
user1-subcarrier2=256
user2-subcarrier3=128
user3-subcarrier1=256
user4-subcarrier4=128

The other constraint is that the subcarrier we have to choose for each user must have data rate<= achievable data rate for each user.
And also I want ilog to give me back after the execution of the code an array with the data rates for each user.
#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: SystemAdmin

Dear Melitis,

to me that sounds like a typical Assignment-Problem. Assign a user
to one of the subcarriers.

To that end, you have binary variables
dvar boolean AssignsubCarriers,Users;

And the coanstaint that one subcarreir can be assigned at most
one user is written as

forall(i in subCarriers)
sum(j in Users) Assigni,j <= 1;

The objective is
maximize
sum(i in subCarriers, j in Users) ci,j*Assigni,j;

where the data-element
float costsubCarriers,Users;
is initialized by the formula you mentioned.
Hope this helps.

Best regards
Norbert
#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: meletis13forever

Thank you all.You helped me very much with my problem!I also understood how to use IBM ILOG!
#DecisionOptimization
#MathematicalProgramming-General