Here I have attached my problem for which I need to find 3 users optimal rates (which forms 3 objective functions separately). What modifications do I need to do this to work properly? Or How do I solve such optimization problems in CVX?? Thanks
CVX does not allow multiobjective problems. You need to choose (at most) one objective per problem. You can take a weighted sum of the individual objectives, or maximize one while constraining the others to some minimum value, or some other method of your choosing.