Shiny Abraham

Joint beamforming and power control in downlink multiuser MIMO systems

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.

Joint transmitter adaptation and power control for cognitive radio networks with target SIR requirements

Abstract In this paper we study joint transmitter adaptation and power control in the uplink of Cognitive Radio (CR) networks with target values imposed on the signal-to-interference +noise-ratios (SINR) at the CR receiver. We use a framework based on block transmissions and linear precoders to formulate this as a constrained optimization problem for which we discuss the conditions that must be satisfied by the optimal solution. We also present an algorithm which adapts the transmit precoder and power values incrementally until a fixed point is reached where the specified target SINRs are achieved with minimum transmitted power. Convergence of the proposed algorithm is discussed and is illustrated with numerical examples obtained from simulations.

Joint transmitter adaptation and power control for downlink wireless systems with target SIR requirements

In this paper we study joint transmitter adaptation and power control in downlink wireless systems with target values imposed on the signal-to-interference+noise-ratios (SINR) at the receiver terminals. We use a general framework based on block transmissions and linear precoders that is applicable to a wide range of wireless systems to formulate this as a constrained optimization problem for which we discuss the conditions that must be satisfied by the optimal solution. We also present an algorithm which adapts the transmit precoder and power values incrementally until a fixed point is reached where the specified target SINRs are achieved with minimum transmitted power. Convergence of the proposed algorithm is investigated and is illustrated with numerical examples obtained from simulations.

Downlink transmitter adaptation based on greedy SINR maximization

In this paper we present algorithms for transmitter adaptation in downlink wireless systems based on maximization of the Signal-to-Interference plus Noise-Ratio (SINR). We investigate their fixed-point properties in various scenarios and their relationship with optimal points in dual uplink scenarios.

Joint beamforming and power control in downlink multiuser multiple-input multiple-output systems

In this paper, we study joint beamforming and power control for downlink multiple-input multiple-output systems with multiple users and target values for signal-to-interference plus noise ratios SINRs. We formulate this as a constrained optimization problem of minimizing total interference subject to constraints on the beamforming vector norms, target SINRs, and total transmit power. Necessary and sufficient conditions satisfied by the optimal beamformer and power allocation are presented, and a new algorithm for joint beamforming and power control is proposed. This adapts the beamforming vectors and transmit powers incrementally, and it stops when the specified SINR targets are achieved with minimum powers. The proposed algorithm is illustrated with numerical results obtained from simulations, which study its convergence and compare it with other similar algorithms. Copyright

On the uplink-downlink duality for Gaussian vector channels with colored noise and applications to CDMA transmitter adaptation

In this paper we study the uplink-downlink duality for Gaussian vector channels with colored noise, and we derive the duality transformations (downlink-to-uplink and vice versa) that imply transmit co-variance matrices for which user rates in uplink and downlink are identical. These transformations are then applied for transmitter adaptation in Code Division Multiple Access (CDMA) systems to obtain an ensemble of downlink CDMA codewords from an optimal ensemble of uplink codewords.