Study On Adaptive Resource Allocation Algorithm In MIMO-OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) is a powerful technique employed in mobile communication systems. Combined with Multi-Input Multi-Output (MIMO) multiple antennas as well as adaptive modulation, it is proven to be robust against frequency selectivity fading and multi-path delay spread. In MIMO-OFDM system over mobile fading channels, each subchannel has different channel capacity because of individual attenuation. Therefore, it is important for a MIMO-OFDM system to adaptively allocate resources (bits,power, etc) according to each subchannel's features. This thesis's main work is studying on adaptive resource allocation algorithm in MIMO-OFDM System. The thesis is considered in two stages. The first stage involves the application of bits and power allocation in single-user MIMO-OFDM applies adaptive modulation in SISO-OFDM is introduced to a general MIMO system by using the Singular Value Decomposition (SVD) to separate the MIMO channel into parallel subchannels. Two algorithms are proposed, one is an improved greedy algorithm for changeable BER based on Margin Adaptive (MA) principle, the other is a bisection technique for search lever in Water-filling theory depending on Rate Adaptive (RA) principle. The analysis and simulation results demonstrate an improved system performance by the proposed algorithms. The second stage discusses the adaptive allocation in multi-user MIMO-OFDM system depending upon the MA principle, which considered subcarrier allocation and bits, power allocation as two processes. That is to say, in first step, subcarrier is allocated to each user, then the bits and power is further distributed to corresponding subcarrier. A subcarrier allocation algorithm is proposed according to each user's the quality of channel knowledge. The simulation shows the proposed scheme in this thesis is feasible.