Joint Transmit and Receive Beamforming for Multi-Relay MIMO-OFDMA   Cellular Networks
  A novel transmission protocol is conceived for a multi-user, multi-relay, multiple-input--multiple-output orthogonal frequency-division multiple-access (MIMO-OFDMA) cellular network based on joint transmit and receive beamforming. More specifically, the network's MIMO channels are mathematically decomposed into several effective multiple-input--single-output (MISO) channels, which are spatially multiplexed for transmission. For the sake of improving the attainable capacity, these MISO channels are grouped using a pair of novel grouping algorithms, which are then evaluated in terms of their performance versus complexity trade-off\footnote{This paper concisely focuses on the transmission protocol proposed in our previous work [1]. For more details, please refer to [1].}. 
Kent Tsz Kan Cheung, Shaoshi Yang, Lajos Hanzo
cs.IT math.IT