Consider the uplink of a CDMA system. Suppose there is only a single cell with just two users communicating to the base-station in the cell.
1. Express mathematically the set of all feasible power vectors to support given cb/I0 requirements (assumed to be both equal to /3).
2. Sketch examples of sets of feasible power vectors. Give one example where the feasible set is non-empty and give one example where the feasible set is empty. For the case where the feasible set is non-empty, identify the component-wise minimum power vector.
3. Now suppose there are two cells with two base-stations and each of the two users can be connected to either one of them, i.e. the users are in soft handoff. Extend parts (1) and (2) to this scenario.
4. For a general number of users, do you think that it is always true that, in the optimal solution, each user is always connected to the base-station to which it has the strongest channel gain? Explain.