Transmit beamforming and power control for cellular wireless systems

TLDR

The paper proposes joint power control and beamforming schemes for cellular systems with adaptive arrays only at base stations. The authors develop algorithms that jointly compute mobile power, receiver diversity vectors, and transmit weight vectors to minimize total transmitted power while ensuring each link’s SINR exceeds a threshold, allowing decentralized implementation in reciprocal networks and centralized operation in nonreciprocal ones, and they evaluate performance against prior methods through numerical simulations. The algorithm finds feasible downlink solutions when they exist, minimizes total transmitted power, can be run decentralized in reciprocal networks, and requires centralized implementation with downlink channel knowledge in nonreciprocal networks.

Abstract

Joint power control and beamforming schemes are proposed for cellular systems where adaptive arrays are used only at base stations. In the uplink, mobile power and receiver diversity combining vectors at the base stations are calculated jointly. The mobile transmitted power is minimized, while the signal-to-interference-and-noise ratio (SINR) at each link is maintained above a threshold. A transmit diversity scheme for the downlink is also proposed where the transmit weight vectors and downlink power allocations are jointly calculated such that the SINR at each mobile is above a target value. The proposed algorithm achieves a feasible solution for the downlink if there is one and minimizes the total transmitted power in the network. In a reciprocal network it can be implemented in a decentralized system, and it does not require global channel response measurements. In a nonreciprocal network, where the uplink and downlink channel responses are different, the proposed transmit beamforming algorithm needs to be implemented in a centralized system, and it requires a knowledge of the downlink channel responses. The performances of these algorithms are compared with previously proposed algorithms through numerical studies.