Improving Energy Efficiency Through Multimode Transmission in the Downlink MIMO Systems
Adaptively adjusting system parameters including bandwidth, transmit power and mode to maximize the "Bits Per-Joule" Energy Efficiency (BPJ-EE) in the downlink MIMO systems with imperfect Channel State Information at the Transmitter (CSIT) is considered in this paper. By mode the authors refer to choice of transmission schemes i.e. Singular Value Decomposition (SVD) or Block Diagonalization (BD), active transmit/receive antenna number and active user number. They derive optimal bandwidth and transmit power for each dedicated mode at first, in which accurate capacity estimation strategies are proposed to cope with the imperfect CSIT caused capacity prediction problem.