R1-151287R1-151287.doc

3GPP TSG RAN WG1#80bis R1-151287 Belgrade, Serbia, 20th – 24th April 2015 Agenda Item: .2 Source: Huawei, HiSilicon Title: DM-RS enhancements for EBF/FD-MIMO Document for: Discussion and decision Introduction In RAN1#80 meeting, DMRS enhancements for EBF/FD-MIMO were discussed. The conclusions are shown as follows [1]: Companies are encouraged to give performance evaluations for higher order MU-MIMO with FTP traffic model focusing on following alternatives until RAN1 #80bis meeting Alt. 1: 12 DM-RS REs with OCC = 4 for up to total 4 layers per scrambling sequence Alt. 2: 24 DM-RS REs with OCC = 2 for up to total 4 layers per scrambling sequence Alt. 3: 24 DM-RS REs with OCC = 4 for up to total 8 layers per scrambling sequence Alt. 4: DM-RS estimation accuracy improvement by advanced receiver assuming interference channel estimation Alt. 5: Larger PRG size Note that other possible alternatives are not precluded Note that combination of multiple alternatives can be considered Companies should model DM-RS channel estimation error and should clarify detailed assumptions in their contributions Companies should model interference covariance estimation matrix for DM-RS channel estimation and should also clarify detailed assumptions in their contributions Note that it is quasi-orthogonal between two scrambling groups which should be modelled in channel estimation error modelling For these enhancement scheme should be compared with Rel-12 LTE scheme with two scrambling sequences or one scrambling sequence In this contribution, based on the conclusions in last meeting, we compare the performance between orthogonal 4 layers transmission and Rel-10 MU transmission schemes, i.e., 2 orthogonal layers MU transmission and 4 non-orthogonal layers MU transmission. Then, we discuss the different potential DMRS enhancement schemes, which support 4 orthogonal layers MU transmission, i.e., Alt. 1 to Alt. 3, and give our views. Comparison between orthogonal 4 layers