Optimal Coordinated Beamforming in the Multicell Downlink with Transceiver Impairments
Physical wireless transceivers suffer from a variety of impairments that distort the transmitted and received signals. Their degrading impact is particularly evident in modern systems with multiuser transmission, high transmit power, and low-cost devices, but their existence is routinely ignored in the optimization literature for multicell transmission. This paper provides a detailed analysis of coordinated beamforming in the multicell downlink. The authors solve two optimization problems under a transceiver impairment model and derive the structure of the optimal solutions. They show numerically that these solutions greatly reduce the impact of impairments, compared with beamforming developed for ideal transceivers. Although the so-called multiplexing gain is zero under transceiver impairments, they show that the gain of multiplexing can be large at practical SNRs.