Study Onadaptive Resourceallocationalgorithms In MIMO-OFDM Systems

The need for high rate data transmission and wireless multimedia services enhances during the development and applications of broadband wireless communication techniques. Multiple Input Multiple Output (MIMO) is an emerging technology which uses multiple antennas at both transmitter and receiver. It takes advantages of space diversity by spatially separated antennas in a multipath environment to boost the system capacity. Orthogonal Frequency Division Multiplexing (OFDM) technology can decompose the frequency-selective fading channel into a group of orthogonal flat fading channel, therefore, it could be applied to the MIMO system for overcoming the impact of multipath fading. MIMO-OFDM, with combined advantages of MIMO and OFDM technology, is considered as the main physical layer technology of the fourth generation mobile communication system.This thesis mainly studies on adaptive subcarrier, bit and power allocation. For Multiuser MIMO-OFDM, multiple-users share the same channel resources simultaneously. These users have different channel characteristics, data and Quality of Service (QoS) requirements. In order to increase the channel capacity and satisfy the users'needs, we need to distribute subcarrier, bit and power to each user appropriately.In this thesis, MIMO-OFDM system has been transformed into parallel subchannels through singular value decomposition(SVD). Then, an adaptive allocation algorithm applied to multiuser MIMO-OFDM systems has been proposed by many researchers to optimize the system performance and decrease the system implementation complexity. Firstly, the general adaptive subcarrier allocation algorithms about multiuser MIMO-OFDM system are introduced. Then the paper proposes an improved algorithm based on greedy principle. The analysis and simulation results demonstrate an improved system performance by known ones. Moreover, an adaptive modulation and power allocation algorithm based on greedy algorithm is studied for single user MIMO-OFDM systems. For Multiuser MIMO-OFDM systems, an Adaptive Resource Allocation algorithm based on Margin Adaptive(MA) is proposed. Finally, the author validates the feasibility of the algorithm in this thesis via simulations.