in narrowband MIMO, the optimal power allocation is water filling in min{Nt,Nr} spatial subchannels. and In high SNR regime, equal power allocation will be achieved almost performance of the optimal one.
i study muti-user MIMO-OFDMA system, assume that one subcarrier can only assign to one user. in this case, the optimal power allocation is 2 dimensional water filling in frequency and spatial domain. i want to solve p(k,n),(k is user and n is subcarrier ) by water-filling in frequency domain and for one subcarrier, equal power allocation used in spatial subchannels. i want to know whether this idea is reasonable or not?
i think your idea is reasonable but with large number of subcarriers the complexity of the system will increase. imagine u have FFT of 256 and 1000 users. You optimization would be p(1000,256). Anyways complexity can be reduced.
Thanks for your reply. It's the truth that there is a big problem of complexity.
I will try other low complexity ways to solve this problem.