Institute of Electrical & Electronic Engineers
Multi-User Multiple-Input and Multiple-Output (MU-MIMO) is a key technology for enhancing the spectrum efficiency in cellular mobile communication systems. In the Long Term Evolution (LTE) -Advanced, Orthogonal Cover Code (OCC) has been introduced for the uplink DeModulation Reference Signal (DMRS), which provides orthogonality of the DMRS between different User Equipment (UEs). This enables different bandwidth allocations for paired UEs of MU-MIMO, which enables flexible frequency selective scheduling and UE pairing. On the other hand, to further enhance the spectrum efficiency in LTE-Advanced, non-contiguous frequency resource allocation based on clustered Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing (clustered DFT-S-OFDM), i.e., multi-cluster transmission, is supported.