Transmit/Receive beamformer design and resource allocation in multiuser MIMO-OFDM systems

This paper studies the transmit/receive beamformers design and resources allocation problem for downlink multiuser MIMO-OFDM systems. We propose an algorithm for jointly optimizing the transmit and receive beamformers and resources allocation to minimize the transmission power and at the same time satisfying userspsila quality of service (QoS) in terms of bit error rate (BER) and minimum data rate. In the proposed algorithm, userspsila transmit/receive beamformers are first designed to maximize the sum-rate of each tone. Based on this tone capacity information, an iterative algorithm is developed to allocate the tones to the users. After the tone allocation, the bit rate allocation of each user at the tones allocated is then determined to minimize the total transmission power under the constraint of minimum data rate. This last problem is formulated as a geometric programming (GP) problem. Compared to the traditional algorithms, the proposed approach can make efficient use of the spatial diversity and the frequency diversity of MIMO-OFDM systems, resulting in improved performance. Numerical examples are conducted to demonstrate the effectiveness of the proposed method.