Power control in uplink and downlink CDMA systems with multiple flow types

We consider a power controlled code division multiple access (CDMA) system with multiple flow types. At each of the N nodes, there are F flow types with different signal-to-interference-and-noise-ratio (SINR) requirements. To keep the complexity of the transmitter low, we assume that each node uses the same power level for all its flows. The single flow case has been fully solved and is well-understood. We concentrate on the multiple flow case, and use a novel and different approach. For the uplink problem with N =2 and F arbitrary, the necessary and sufficient conditions to have a solution are found and proved. For the general N >1 uplink problem, we provide a necessary condition for the problem to have a solution and an iterative algorithm to find the optimum solution. For the downlink case with F >1 some properties of the optimal sequences are obtained.