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.
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