POWER CONTROL AND MIMO BEAMFORMING IN CDMA MOBILE COMMUNICATION SYSTEMS (original) (raw)
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2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008
In this paper, we present numerical results to show the performance of power control (PC) by using antenna arrays at the base station (BS). We show that the diversity generated by antenna array, decreases the outage probability, the bit error rate (BER), the fluctuations of the received signal to interference ratio (SIR) over the target SIR, the transmitted power level, and finally increases the speed of convergence of power control algorithms in compared without diversity. These results also increase the system capacity and the quality of service (QoS).
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1999
CDMA systems are limited by the interference that users create for each other. Several methods of controlling and/or suppressing the interference through power control, multiuser detection (temporal filtering) and beamforming (spatial filtering) are studied to increase the capacity of CDMA systems [1-3]. We investigate the capacity increase that is possible by combining power control with intelligent temporal and spatial receiver filter design. The SIR maximizing joint temporal-spatial receiver filters in unconstrained and constrained filter spaces are derived. Two-step iterative power control algorithms that converge to the optimum powers and the joint temporal and spatial receiver filters in the corresponding filter domains are given. A power control algorithm with less complex filter update procedure is given. It is observed that significant savings in total transmit power expended by all users in the system are possible if filtering in both domains are utilized compared with conventional power control and joint optimal power control and filtering in one domain.
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Abstract The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to increase the capacity in wireless communication networks. The minimum variance beamformer maximizes the carrier to interference ratio (CIR) when it is employed in the receiver of a wireless link. In a system with omnidirectional antennas, power control algorithms are used to maximize the CIR as well.
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ece.odu.edu
In this paper we discuss joint beamforming and power control for downlink multiuser MIMO systems with target signal-to-interference+noise ratios (SINR) constraints. We derive necessary conditions for minimizing total interference at downlink receivers and present an algorithm which adapts the beamforming vectors and powers incrementally to meet specified SINR targets with minimum powers. The proposed algorithm is illustrated with numerical examples obtained from simulations.
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