tailieunhanh - Báo cáo toán học: " Improving energy efficiency through multimode transmission in the downlink MIMO systems"

Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học được đăng trên tạp chí toán học quốc tế đề tài: Improving energy efficiency through multimode transmission in the downlink MIMO systems | Xu et al. EURASIP Journal on Wireless Communications and Networking 2011 2011 200 http content 2011 1 200 o EURASIP Journal on Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Improving energy efficiency through multimode transmission in the downlink MIMO systems Jie Xu1 Ling Qiu1 and Chengwen Yu2 Abstract Adaptively adjusting system parameters including bandwidth transmit power and mode to maximize the Bits perJoule energy efficiency BPJ-EE in the downlink MIMO systems with imperfect channel state information at the transmitter CSIT is considered in this article. By mode we refer to choice of transmission schemes . singular value decomposition SVD or block diagonalization BD active transmit receive antenna number and active user number. We 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. Then an ergodic capacity-based mode switching strategy is proposed to further improve the BPJ-EE which provides insights into the preferred mode under given scenarios. Mode switching compromises different power parts exploits the trade-off between the multiplexing gain and the imperfect CSIT caused inter-user interference and improves the BPJ-EE significantly. Keywords Bits per-Joule energy efficiency BPJ-EE downlink MIMO systems singular value decomposition SVD block diagonalization BD imperfect CSIT 1. Introduction Energy efficiency is becoming increasingly important for the future radio access networks due to the climate change and the operator s increasing operational cost. As base stations BSs take the main parts of the energy consumption 1 2 improving the energy efficiency of BS is significant. Additionally multiple-input multipleoutput MIMO has become the key technology in the next generation broadband wireless networks such as WiMAX and 3GPP-LTE. Therefore