Scheduling algorithms and throughput maximization for the downlink of packet-data cellular systems with multiple antennas at the base station

作     者：Mazzarese, David J. Krzymien, Witold A. 

作者机构：Telecommun R&D Ctr Adv Res Lab Samsung Elect Suwon South Korea Univ Alberta Elect Comp Engn TR Labs Edmonton AB T6G 2M7 Canada 

出 版 物：《WIRELESS PERSONAL COMMUNICATIONS》 (无线个人通信)

年 卷 期：2007年第43卷第2期

页      面：215-260页

核心收录：

学科分类：0810[工学-信息与通信工程] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 

基　　金：TRLabs Natural Sciences and Engineering Research Council of Canada, NSERC Ministero dell’Istruzione, dell’Università e della Ricerca, MIUR 

主　　题：MIMO systems multiuser channels sum-capacity scheduling algorithms 

摘      要：The capacity-achieving coding scheme for the multiple-input multiple-output (MIMO) broadcast channel is dirty-paper coding. With this type of transmission scheme the optimal number of active users that receive data and the optimal power allocation strategy are highly dependent on the structure of the channel matrix and on the total transmit power available. In the context of packet-data access with adaptive transmission where mobile users are equipped with a single receive antenna and the base station has multiple transmit antennas, we study the optimal number of active users and the optimal power allocation. In the particular case of two transmit antennas, we prove that the optimal number of active users can be a non-monotonic function of the total transmit power. Thus not only the number of users that should optimally be served simultaneously depends on the user channel vectors but also on the power available at the base station transmitter. The expected complexity of optimal scheduling algorithms is thus very high. Yet we then prove that at most as many users as the number of transmit antennas are allocated a large amount of power asymptotically in the high-power region in order to achieve the sum-capacity. Simulations confirm that constraining the number of active users to be no more than the number of transmit antennas incurs only a marginal loss in spectral efficiency. Based on these observations, we propose low-complexity scheduling algorithms with sub-optimal transmission schemes that can approach the sum-capacity of the MIMO broadcast channel by taking advantage of multiuser diversity. The suitability of known antenna selection algorithms is also demonstrated. We consider the cases of complete and partial channel knowledge at the transmitter. We provide simulation results to illustrate our conclusions.