1. WF on transmit diversity for DFTsOFDM
3GPP TSG RAN WG1 Meeting RAN1 #88b
Spokane, USA, April 3-7, 2017
Agenda item:
Document for: Decision
R1-170XXXX
WF on transmit diversity for DFTsOFDM
Mitsubishi Electric, Qualcomm, Interdigital,…

2. Background RAN1#NR AH#1 RAN1#88
For PUCCH in long-duration, DFT-s-OFDM waveform is supported.
For PUCCH in long-duration, transmit antenna diversity is supported.
RAN1#88
For DFT-S-OFDM, following schemes can be candidates for UL diversity schemes for UL data: CDD, precoder cycling, antenna port switching, SFBC, and STBC.
RAN1 should down select them in WI phase.
FFS the corresponding spec impact (if any)
For DFT-S-OFDM based transmission
PRB bundling size is the whole scheduled bandwidth if the scheduled bandwidth comprises a single cluster.

3. Background
Transmit diversity increases the link reliability in DFTsOFDM for both data and control
Rank 1 transmission, link budget limited, unreliable or absent channel information
Low PAPR Alamouti schemes able to operate with any number of DFTsOFDM symbol were proposed (SC-SFBC, SS-STBC, STBC)
R , R , R , R , R , R

4. Background Frequency-domain precoder-cycling is not fit for DFTsOFDM
PRB/PRG cycling is PAPR destroying
RE-based cophase cycling (1/2 symbol LD-CDD) has limited performance gain (R )
Time-domain antenna/precoder switching has high DM-RS overhead (1 DM-RS per antenna/precoder) and poor performance at medium/high speed (no time-domain interpolation) (R )
At least for long PUCCH, Alamouti-based transmit diversity overperforms CDD
R , R

5. Proposal
For DFTsOFDM in data and control channel, the following schemes are candidates for transmit diversity:
Low PAPR Alamouti-based transmit diversity, short delay CDD