Power and signature optimization for downlink CDMA

User signature sequences and powers are jointly optimized with linear receivers for forward link code-division multiple access (CDMA). The channels are assumed to be stationary and known to the transmitter. Both voice and data services are considered, which have different requirements. For the voice service, the signatures are selected to minimize the total transmitted power, subject to a constraint on received mean squared error (MSE). For the data service, the signatures are selected to maximize the total mutual information summed over the users, subject to a transmitted power constraint. In the latter case, we show that the optimized user signatures are orthogonal.