Abstract: Aiming at the problem of unreasonable resource allocation due to incomplete information of hierarchical design in the downlink of multi-user MIMO-OFDM ( Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) system，a cross-layer resource allocation algorithm is proposed to maximize the system throughput with the constraint of each user's data rate． The algorithm maximizes the system throughput with given transmission power and users' minimal rate constraints，it implements the joint subcarrier and power allocation considering the QoS( Quality of Service) constraints of different users，the queue state of MAC( Media Access Control) layer and the physical layer's channel state information． Simulation results show that the proposed algorithm can satisfy the QoS requirements of different users，achieve high system throughput．

Key words: multiuser multiple input multiple output-orthogonal frequency division multiplexing ( MIMOOFDM), cross-layer resource allocation, quality of service ( QoS ) requirements, system throughput