User Scheduling and Partner Selection for Multiplexing-based Distributed MIMO Uplink Transmission

During the last decade, multiple-input multiple-output (MIMO) systems, where both the transmitter and receiver are equipped with multiple antennas, have been verified to be a very promising technique to break the throughput bottleneck in future wireless communication networks. Based on countless results of analysis and field measurements that have been undertaken by many researchers around the world, it is indubitable that MIMO transceiver schemes can significantly improve the system performance. Some wellknown standards for next-generation wireless broadband, including 3GPP Long Term Evolution (LTE) and IEEE 802.16 (WiMAX), adopt MIMO as a key feature of the physical layer. For instance, the standard of IEEE 802.16e supports three possible options of advanced antenna systems (AAS), namely transmit diversity (TD), beamforming (BF), and spatial multiplexing (SM). The extensions of these multi-antenna techniques are also envisaged in future standards such as IEEE 802.16m and LTE-A. The potential benefits of MIMO systems are mainly attributed to the multiplexing/diversity gains provided by multiple antenna elements. With spatial multiplexing, multiple independent data streams are transmitted in a single time/frequency resource allocation, so spectral efficiency is thereby increased. In practice, it may be difficult, if not impossible, to equip multiple antenna elements at mobile stations (MS) due to their small physical sizes. In such cases, concurrent transmission of multiple data streams is not feasible, as the maximum number of data streams is limited by ( , ) t r m min M M = , where t M and r M are the number of