An overview of multi-mode multi-user adaptation and scheduling techniques in mimo-based fourth-generation wireless systems

MIMO-OFDM is widely recognized today as a key combination of technologies to achieve high spectral efficiency and high link reliability over space and frequency selective wireless channels, at a reasonable hardware cost. Both OFDM and MIMO have a variety of modes of operation and parameters and for each channel state, users¿ requirements of data transmission and criterion of estimation performance, there is an optimal scheme and set of parameters based on channel state information. Adaptive switching between MIMO-OFDMA schemes yields significant capacity gains over fixed transmission schemes. A combination of modulation and coding scheme and MIMO method maximizes the throughput whilst satisfying a predefined average BER.