OFDMMIMOMATLAB仿真程序MIT研究人员贡献-MIMO_OFDM.rar OFDM MIMO MATLAB仿真程序 MIT研究人员贡献： Adaptive Loading in MIMO/OFDM Systems Prateek Bansal Andrew Brzezinski prateek@stanford.edu brzezin@stanford.edu December 13, 2001 Abstract Orthogonal Frequency Division Multiplexing is a powerful technique employed in communications systems suering from frequency selectivity. Combined with multiple antennas at the transmitter and receiver as well as adaptive modulation, OFDM proves to be robust against channel delay spread. Furthermore, it leads to signicant data rates with improved bit error performance over links having only a single antenna at both the transmitter and receiver. This project demonstrates OFDM with adaptive modulation applied to Multiple-Input Multiple- Output systems. We apply an optimization algorithm to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge. The analysis and simulation is considered in two stages. The rst stage involves the application of a variable-rate variable-power MQAM technique for a Single-Input Single-Output OFDM system. This is compared with the performance of xed OFDM transmission where a constant rate is applied to each subcarrier. The second stage applies adaptive modulation to a general MIMO system by making use of the Singular Value Decomposition to separate the MIMO channel into parallel subchannels. For a two-input antenna, two-output antenna system, the performance is compared with the performance of a system using selection diversity at the transmitter and maximal ratio combining at the receiver.

MIT实验室研究出了一种数据库加密软件，这部分是cryptdb代理的实例操作