QRD-based MU-MIMO transmission scheme towards evolved LTE TDD system

With the active evolvement of 3GPP long term evolution (LTE) system, advanced multi-user multiple-input multiple-output (MU-MIMO) transmission schemes attract more and more interests in engineering field. However, in order to bring advanced MU-MIMO techniques from theory to practice, there are two major obstacles to overcome, i.e., how to obtain accurate channel state information at the transmitter side (CSIT) and how to achieve high spectrum efficiency with low computational complexity. In this paper, we propose QR decomposition (QRD) based MU-MIMO transmission scheme towards evolved LTE time division duplex (TDD) system, which can orthogonalize the multiple data streams to/from multiple users in downlink/uplink with TDD ping-pong transmission to realize high spectrum efficiency, thanks to the accurate downlink/uplink CSIT obtained via the channel reciprocity and the downlink/uplink reference signal (RS) in evolved LTE TDD system. Furthermore, it only needs low-complexity QRD operation, which can simplify the transceiver structure significantly to facilitate its implementation in practice. Computer simulation results demonstrate the effectiveness of our proposal and suggest it a promising candidate of advanced MU-MIMO transmission schemes towards evolved LTE TDD system.