Energy Efficient Beamforming Design Ior Multi-Carrier Multi-user Systems with Nonlinear Amplifiers

The energy efficiency (EE) maximization problem is studied for the design of beamforming for multi-carrier multiuser systems. Nonlinear amplifier at each antenna as well as per-antenna power constraints at the transmitter are considered. The quality-of-service (QoS) of each user is guaranteed by a minimal transmission rate. Because the power allocation variables and the beamforming vectors are coupled in the original problem, which makes it difficult to handle, we split the problem into two subproblems. The first subproblem, which optimizes the power allocation, can be formulated as a geometric programming (GP) after the term related to power consumption is approximated as a monomial. The second subproblem, which optimizes the beamforming, is formulated as a second-order cone programming (SOCP). Numerical results illustrate the effect of EE maximization on rates and the effect of circuit power and amplifier efficiency on EE