Resource Allocation In Beamforming-Based Multiuser Mimo-OFDM Systems

MIMO-OFDM is a main technique of the future-generation wireless mobile communication,which combines MIMO (Multiple-Input and Multiple-Output) and OFDM (Orthogonal Frequency Division Multiplexing) technique to greatly increase the system capacity and spectral efficiency. A MIMO system takes advantage of the spatial diversity that is obtained by spatially separated antennas in a dense multi-path scattering environment. The employment of MIMO systems can obtain a significant capacity gain in band limited wireless system, which makes high rate transmission possible. OFDM is a multi-carrier modulation method that has high frequency efficiency and can perfectly eliminate the effects of the ISI. The combination of OFDM and MIMO has become one of the promising core technologies in the next generation telecommunication system.Applying adaptive resources allocation such as adaptive carrier allocation, low-complexity bit loading and power allocation algorithms to MIMO - OFDM systems is one most important basis to obtain best performance. By dynamically adapting modulation, rates, power as well as other transmission coefficients according to the instantaneous channel characteristics, performances of a given system can be optimized.This paper explores various MIMO-OFDM resource allocation algorithm, and studies beamforming design and resource allocation in OFDM systems as two main problems. In beamforming design, the influence of partial channel state information is considered, and a corresponding corrected equation is given. This paper also studies the beamforming scheme with limited feedback data, which assures the transmit efficiency meanwhile limits the feedback data in a fixed level. In resource allocation in OFDM system, different schemes under maximum transmit rate principle and minimum transmit power principle are presented and the typical schemes are studied under simulation.