Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article A Design Framework for Scalar Feedback in MIMO Broadcast Channels | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 574784 12 pages doi 2008 574784 Research Article A Design Framework for Scalar Feedback in MIMO Broadcast Channels Ruben de Francisco and DirkT. M. Slock Eurecom Institute BP 193 06904 Sophia-Antipolis Cedex France Correspondence should be addressed to Ruben de Francisco Received 15 June 2007 Revised 6 October 2007 Accepted 13 November 2007 Recommended by Markus Rupp Joint linear beamforming and scheduling are performed in a system where limited feedback is present at the transmitter side. The feedback conveyed by each user to the base station consists of channel direction information CDI based on a predetermined codebook and a scalar metric with channel quality information CQI used to perform user scheduling. In this paper we present a design framework for scalar feedback in MIMO broadcast channels with limited feedback. An approximation on the sum rate is provided for the proposed family of metrics which is validated through simulations. For a given number of active users and average SNR conditions the base station is able to update certain transmission parameters in order to maximize the sum-rate function. On the other hand the proposed sum-rate function provides a means of simple comparison between transmission schemes and scalar feedback techniques. Particularly the sum rate of SDMA and time division multiple access TDMA is compared in the following extreme regimes large number of users high SNR and low SNR. Simulations are provided to illustrate the performance of various scalar feedback techniques based on the proposed design framework. Copyright 2008 R. de Francisco and D. T. M. Slock. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION .
