This paper addresses energy-efficient link adaptation for downlink multiuser multiple-input-multiple-output (MIMO) systems. Different from the previous works on energy efficient MIMO techniques, we take into account finite pilot power and the corresponding effect of imperfect channel state information (CSI) at the users. We analyze the average throughput and define the energy efficiency (EE) of downlink multiuser MIMO systems. We show that the EE of the system is not jointly quasi-concave with respect to pilot power, data power, and transmission rate. For this reason, we propose an efficient algorithm that alternately updates pilot power, data power, and transmission rate to improve the EE of the system. Simulation results show that the proposed scheme significantly enhances the EE, and the resulting EE is comparable to the maximal EE obtained by the exhaustive search.
Bibliographical notePublisher Copyright:
© 1967-2012 IEEE.
All Science Journal Classification (ASJC) codes
- Automotive Engineering
- Aerospace Engineering
- Electrical and Electronic Engineering
- Applied Mathematics