WF on pre-DFT PT-RS pattern for DFTsOFDM RAN1#90b, Prague, Czech Republic, October 2017 Agenda item: 7.2.3.4 R1-171XXXX WF on pre-DFT PT-RS pattern for DFTsOFDM Mitsubishi Electric, Ericsson, Nokia, NSB, IITH, IITM, CeWit, Tejas Networks, Reliance Jio, Spreadtrum, Sony, CMCC, Interdigital, Huawei, HiSilicon, AT&T, Samsung, ZTE, Sanechips, Sharp [DoCoMo, Vodafone]

Background The following agreements were made in the past meetings: [RAN1#89] Uplink PTRS for DFT-s-OFDM waveform is supported. Presence of PTRS for DFT-s-OFDM is UE-specifically configurable Multiple pattern/density of PTRS for DFT-s-OFDM is supported FFS: implicit or explicit signaling [RAN1 NR AH#02] Support at least full symbol-level time density for time-domain PT-RS for DFT-S-OFDM (every PUSCH carrying symbol) FFS: whether to support configurable symbol-level time density for time-domain PT-RS density reduction for DFT-S- OFDM Note: If supported, the configuration can be implicit (associated with scheduled MCS and/or BW and/or DM-RS port(s)/position) or explicit, which is to be decided in next meeting [RAN1#90] Confirm WA: Support Pre-DFT PT-RS insertion for UL DFT-S-OFDM.

Background Concerning the exact pre-DFT pattern, the following was agreed [RAN1 NR AH#03] For chunk-based pre-DFT PTRS insertion for DFTsOFDM, support the following The supported values for K (chunk size) are 2 and 4 Implicit configuration depending on MCS/BW The supported values for X (number of chunks/DFTsOFDM symbol) are at least 2 and 4 X implicitly depends on allocated bandwidth and/or MCS and/or K value Implicit configuration can be subcarrier spacing dependent FFS if K=1 is also supported and exact mechanism When X=2 is configured, downselect among the following: Alt. 1: chunks are placed head/tail of DFTsOFDM symbols containing PTRS Alt. 2: chunks are placed middle/tail of the DFTsOFDM symbols containing PTRS Alt. 3: chunks are placed head/middle of the DFTsOFDM symbols containing PTRS Alt. 4: chunks are placed middle of each of the X equally-sized parts of the DFTsOFDM symbols containing PTRS For PTRS sequence, downselect from the following options: Option 1: pi/2 BPSK PTRS is used for pi/2 BPSK PUSCH [FFS] PTRS sequence consists of the outermost points of the PUSCH constellation Option 2 Reuse the same sequence as PTRS or DMRS sequence for UL CP-OFDM FFS: Time-domain PTRS density reduction is supported at least for allocated bands below N RB and/or some MCS Time-domain pattern depends on DM-RS positions (DFTsOFDM positions near DMRS do not contain PTRS) FFS: N value FFS: every other DFTsOFDM symbol not neighbouring DM-RS positions does not contain PTRS For RB allocation larger than N, PTRS density reduction is configured by RRC

Proposals For chunk-based pre-DFT PTRS insertion for DFTsOFDM with X chunks of size K>1, support the following For K=2, the samples in DFT domain are divided in X intervals, and the chunks are located in the first K samples of each interval For K=4, the samples in DFT domain are divided in X intervals, where in the first interval the chunk is placed in the Head (first K samples), in the last interval the chunk is placed in the Tail (last K samples), and in the rest of intervals the chunk is placed in the middle of the interval For PTRS for DFT-s-OFDM, support RRC-configured association between chunk-size/chunk-number and scheduled BW according to the table below FFS default UE behaviour before RRC configuration FFS value of Y (if different than 4) FFS whether thersholds are MCS and/or subcarrier spacing dependent Note: NRB0 can be equal to 0; when NRB0 is superior to 0, no PTRS is present for allocations less or equal to NRB0 Possible PTRS presence/absence is configured through RRC Time-domain PTRS density is configured by RRC between every symbol and every other symbol Time-domain pattern depends on DM-RS positions (DFTsOFDM positions after and/or before DMRS do not contain PTRS) Scheduled BW X x K NRB0<NRB ≤NRB1 2x2 NRB1 <NRB≤NRB2 2x4 NRB2<NRB≤NRB3 4x2 NRB3<NRB≤NRB4 4x4 NRB > NRB4 Yx4

References The following documents relating to pre-DFT PTRS pattern were submitted to RAN1#90b R1-1717306 Further details of PTRS Huawei, HiSilicon R1-1717374 Remaining details on PT-RS Intel Corporation R1-1717478 Discussion on the remaining details on PT-RS vivo R1-1717631 Discussion on PT-RS Samsung R1-1717746 Remaining issues on PT-RS Spreadtrum R1-1717760 On chunk-based for UL DFTsOFDM waveform Mitsubishi Electric R1-1717882 Discussion on PT-RS design CMCC R1-1718072 PT-RS support for pi/2 BPSK PUSCH IITH R1-1718199 Remaining details on PT-RS NTT DOCOMO, INC. R1-1718449 Details on PT-RS design Ericsson R1-1718484 Remaining issues on PT-RS InterDigital, Inc. R1-1718517 On remaining details of PT-RS design Nokia, Nokia Shanghai Bell R1-1718548 PTRS considerations Qualcomm Incorporated