Beamforming and power control for multirate CDMA systems with per-path-per-weight beamforming scheme
Joint beamforming and power control is a powerful means for suppressing interference and increasing capacity in direct-sequence code-division multiple-access (DS-CDMA) systems. In micro or picocell environment, the angular separation between each path of the same user is relatively large, thus per-user-per-weight (PUPW) beamforming scheme suffers from strong inter-finger interference (IFI). In order to suppress both multiple-access interference (MAI) and IFI effectively. In this paper, we consider the problem of joint beamforming and power control when per-path-per-weight (PPPW) beamformer is employed in a multirate DS-CDMA system with multicode scheme. The optimal solution of the beamforming weights and transmitted powers is obtained by taken into account the data information of all users and minimizing the power radiated by the mobile terminals while maintaining the SIR requirements. Computer simulations show that for 5 user environment with SIR threshold of 6.8 dB, PPPW scheme saves about 7 dB total transmission power than PUPW scheme when the angular spread is 20 degree.