Performance analysis of variable-power adaptive modulation in space-time block coded MIMO diversity systems  

作　　者：YU XiangBin SHI HuiBin 

机构地区：[1]College of Information Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China [2]National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China

出　　处：《Science China(Information Sciences)》2010年第10期2106-2115,共10页中国科学（信息科学）（英文版）

基　　金：supported by the Doctoral Fund of Ministry of Education of China (Grant No. 20093218120021);the Open Research Fund of National Mobile Communications Research Laboratory, Southeast University (GrantNo. N200904);NUAA Research Funding (Grant No. NS2010113);the Startup Fund of NUAA (Grant No.S0855-041)

摘　　要：In this paper, the performance analysis of multi-antenna MIMO systems with variable-power （VP） adaptive modulation and space-time coding is presented. The fading gain value is partitioned into a number of regions by which we decide the transmission power according to the region the fading gain falls in. The optimum fading gain region boundaries （switching thresholds） for maximizing spectrum efficiency （SE） under a target BER and average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimization will be unique if the existence condition for multi-antenna systems is satisfied, and is unique for single antenna systems. A practical iterative calculation method based on Steepest Descent Algorithm for finding the Lagrange multiplier is proposed. With the switching thresholds, the closed-form expressions of the SE and average BER, respectively for VP system and constant-power （CP） system are achieved. Simulation results for SE and average BER are in good agreement with the theory analysis. The results show that VP adaptive modulation with space-time coding provides better SE than the counterpart with CP under a target BER and average power constraint.In this paper, the performance analysis of multi-antenna MIMO systems with variable-power （VP） adaptive modulation and space-time coding is presented. The fading gain value is partitioned into a number of regions by which we decide the transmission power according to the region the fading gain falls in. The optimum fading gain region boundaries （switching thresholds） for maximizing spectrum efficiency （SE） under a target BER and average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimization will be unique if the existence condition for multi-antenna systems is satisfied, and is unique for single antenna systems. A practical iterative calculation method based on Steepest Descent Algorithm for finding the Lagrange multiplier is proposed. With the switching thresholds, the closed-form expressions of the SE and average BER, respectively for VP system and constant-power （CP） system are achieved. Simulation results for SE and average BER are in good agreement with the theory analysis. The results show that VP adaptive modulation with space-time coding provides better SE than the counterpart with CP under a target BER and average power constraint.

关 键 词：adaptive modulation variable power space-time block code constant power multiple inputmultiple output （MIMO） 

分 类 号：TN919.3[电子电信—通信与信息系统]