1. Proposals on remaining issues on PDCCH structure
3GPP TSG RAN WG1 Meeting 90bis
Prague, CZ, 9th – 13th, October 2017
Agenda item:
R1-17xxxxx
Proposals on remaining issues on PDCCH structure
NTT DOCOMO, INC.

2. Proposal on PDCCH DMRS
Confirm the WA: DMRS is evenly distributed within a REG
DMRS REs are #1, #5, #9
DMRS sequence is a Gold sequence as in LTE
Note: in case if new Gold sequence is introduced for NR, this would be revisited
DMRS sequence for NR-PDCCH can be obtained according to a reference point in frequency domain.
The sequence is generated from the lowest PRB of the CORESET, and the length is equal to the number of PRBs between the lowest and the highest PRBs of the CORESET.
The seed depends on the OFDM symbol of the CORESET.

3. Proposal on wideband RS for PDCCH
Confirm the WA with the following clarifications:
For a CORESET, precoder granularity in frequency domain is:
Configurable between i) equal to the REG bundle size in the frequency domain; or ii) equal to the number of contiguous RBs in the frequency domain within the CORESET
For ii), DMRS is mapped over all REGs within CORESET.
RAN1 assumes that CORESET for PDCCH scheduling RMSI can be configured with Option i)
In Option ii) UE may assume DMRS is present in all REGs within the set of contiguous RBs of the CORESET where at least one REG of a candidate is mapped.

4. Proposal on PDCCH DMRS Whether to conform the working assumption?
For a CORESET, precoder granularity in frequency domain is:
Configurable between i) equal to the REG bundle size in the frequency domain; or ii) equal to the number of contiguous RBs in the frequency domain within the CORESET
For ii), DMRS is mapped over all REGs within the CORESET.

5. Issue 0: Wideband RS - Discussions
Parameter
Value
Carrier Frequency
4 GHz
Control Resource Set Bandwidth
18 MHz
Sub-carrier Spacing
15 kHz
DCI Payload Size
20 bits + CRC
Modulation
QPSK
Channel Coding
Polar code with CRC-aided list-8 decoder; 19bit CRC
Aggregation Level 8
REG bundle size
6 REGs per bundle
Number of OFDM symbols for NR-PDCCH 1
Channel Model
TDL-A 30ns; TDL-B 300ns; TDL-C 30ns; TDL-C 300ns; 3kmph UE speed
gNB antenna configuration
2Tx
UE antenna configuration
2Rx
Channel Estimation
Practical with MRC
Noise Estimation
Ideal
Transmission Diversity Scheme
1-port precoder cycling for ’inband RS’
S-CDD for ’wideband RS (65ns delay)
Resource mapping
Distributed transmission
DMRS density
1/4
R (Ericsson)

6. Issue 0: Wideband RS - Discussions
R (ZTE)
Item
Value
Channel
TDL-A
DS = 300ns, 1000ns
Speed = 3kmph
Antenna
2*2
Frequency
4GHz
Numerology
BW = 10MHz(50RB)
SCS = 15kHz
DMRS overhead
1/4
Aggregation level 8
CCE size
6 REGs per CCE
Bundle size
3/6
Payload size
20+16(CRC)
Transmit scheme
sCDD
Mapping scheme
Interleaving
CORESET duration
3OFDM symbol(s)
Coding
TBCC
Channel estimation
MMSE

7. Issue 0: Wideband RS - Discussions
R (CATT)
Parameter
Value NR
LTE
Channel
TDL-C-1000ns
System BW (RBs)
10 MHz
CORESET BW 50
CORESET duration 2
CFI = 2
Number of TX ports 1
2 CRS ports
Tx Diversity
1 port with precoder cycling
SFBC
Antenna configuration
2Tx 2Rx AL
2,4,8
CCE-to-REG mapping
Time-first mapping, LTE PDCCH interleaver
DCI size
60bits+16bits CRC
DMRS density
1/4
REG bundling size 6
For 6 BS: 3 in freq, 2 in time
Precoder granularity
REG Bundle size in frequency domain;
Wideband RS

8. Issue 0: Wideband RS - Discussions
ZTE comments:
1: SINR of -6dB is achievable even without wideband RS
2: Wideband RS consumes more energy
3: Wideband RS creates more inter-cell interference
4: Wideband RS makes resource sharing b/w PDCCH and PDSCH more difficult
5: Wideband RS makes beam-forming/multiplexing more difficult