For multiuser multiple-input multiple-output (MIMO) uplink communications where the signal-to-interference-plus-noise ratio (SINR) of the k-th user, denoted as SINR k , is expected to achieve the target value  γk , we first consider the ideal scenario where multiuser channel matrices are perfectly known to every user and we solve the problem of maximizing min k (SINR k / γk ) over all possible beamformers under individual transmit power constraints via alternating optimization strategies and the generalized eigenvalue problem (GEVP) programming. Then, we study a more realistic situation where only a few number of bits are allowed to feed back to users. We propose to integrate the genetic algorithm into the Lloyd's vector quantization method to design the optimum codebook in terms of maximizing E(min k (SINR k / γk )) with expectation taken with respect to fading channels.
['Songnan Xi', 'Michael D. Zoltowski']
Multiuser transmit beamforming for MIMO uplink with individual SINR targets