chih-hsuan chen chttl 2016/05/06 - 工研院資通所參與4g, 3gpp, ieee 802.16,lte...

1/17 中華電信研究院版權所有

Chih-Hsuan Chen

CHTTL

2016/05/06

2/17

中華電信研究院版權所有

Background

Rel-13 status

Rel-14 and beyond

3/17


Base station equipped with Active Antenna Array (AAS) and able to exploit the full 3D channels

Conventional BS can only do beamforming in one direction (horizontal)

Improve indoor coverage in urban scenario

Increase cell-edge and average cell capacity

Improve cell capacity

3D beamforming Vertical sectorization

Higher order MUMIMO

4/17


Objective: study enhancements and assess performance benefits of 2D antenna array

2D antenna array with 8 or more TXRUs

Channel model

3D channel model development

• 2013-01~2014-03(RAN1#72~#78)

FD-MIMO SI

Study FD-MIMO performance

• 2014-10~2015-06(RAN1#78b~#81)

FD-MIMO WI

FD-MIMO standard specification

• 2015-08~2015-11(RAN1#82~#83)

Development timeline

5/17


Evaluation scenarios in FD-MIMO SI:

Scenario

Urban Macro (2GHz)

Urban Micro (3.5GHz)

Non co-channel HetNet

Co-channel HetNet

Main Supporting Company

Samsung, Nokia, Ericsson, ALU, Huawei, ZTE, CMCC

Samsung, Nokia, Ericsson, ALU, Huawei, ZTE, CMCC

NTT DOCOMO, KDDI, Softbank

AT&T, Orange

Number of evaluation results (Phase-1)

FDD TDD FDD TDD FDD TDD FDD TDD

14 6 14 6 5 0 2 0

The main focus is still on Urban Macro

and Urban Micro for Rel-13 FD-MIMO SI. Ref: TR 36.897

6/17


No new Transmission Mode for FD-MIMO

Supported by TM9 and TM10

Rel-13 FD-MIMO specification primary includes the following parts:

Non-precoded CSI-RS

• Increase CSI-RS port to 12 and 16

Beamformed CSI-RS

CSI reporting enhancement

• To support non-precoded and beamformed CSI-RS

DM-RS enhancement

• Additional DM-RS port to support higher order MU-MIMO

SRS enhancement

• Increase SRS measurement resources

7/17


This category comprises schemes where different CSI-RS ports have the same wide beam width and direction and hence generally cell wide coverage.

CSI-RS port number can be larger than 8 (12/16-port)

12/16-port codebook design (max. 8 layers)

Ref: TR 36.897

CSI feedback (PMI, RI, CQI)

8/17


Ref: TS 36.211

In Rel-12, there are {1,2,4,8} CSI-RS ports

In Rel-13, CSI-RS port number can be {12, 16}

Total number of

antenna ports

Number of antenna ports

per CSI-RS configuration

Number of CSI-RS

configurations

12 4 3

16 8 2

1/2 CSI-RS: 4 CSI-RS: 8 CSI-RS:

12 CSI-RS: 16 CSI-RS:

9/17


This category comprises schemes where CSI-RS ports have narrow beam widths and hence not cell wide coverage, and at least some CSI-RS port-resource combinations have different beam directions.

CSI-RS port number per beam ≦ 8

Ref: TR 36.897

CRI (CSI-RS Resource Indication) + CSI feedback (PMI, RI, CQI)

10/17


Class A CSI reporting (non-precoded CSI-RS)

PMI reporting is also two stage: W=W1W2

12/16-port codebook:

There are 5 parameters require RRC config.

• (N1,N2)：dimension of two different directions

• (O1,O2)：sampling factor for (N1,N2)

• Config={1,2,3,4}: codebook subset for beam selection and co-phasing

(N1,N2) (O1,O2) combinations

(8,1) (4,-), (8,-)

(2,2) (4,4), (8,8)

(2,3) {(8,4), (8,8)}

(3,2) {(8,4), (4,4)}

(2,4) {(8,4), (8,8)}

(4,2) {(8,4), (4,4)}

8-port

codebook

Rank-1 codebook config.

Ref: 3GPP R1-156217

11/17


Class B CSI reporting (beamformed CSI-RS)

BS can configure K beams for UE

• K=1~8

• CSI-RS port number for each beam=1,2,4,8

UE report CRI (CSI-RS Resource Indication) to indicate the preferred beam

• CRI is wideband

• RI/CQI/PMI based on legacy codebook (i.e. Rel-12)

• CRI reporting period is integer multiple of RI

Report CRI=2

RI/CQI/PMI is

measured on

CSI-RS 2

12/17


Conventionally, CSI is derived by averaging over measurement in multiple subframes.

In Rel-13, Measurement Restriction (MR) allows BS to configure UE to derive measurement report by using only single subframe

Configured by RRC signaling

Channel MR: only applies Class B

Interference MR: both Class A and Class B

Example: BS can apply different beamformed CSI-RS direction in consecutive subframes

Subframe 1 Subframe 2 Subframe 3 Subframe 4

13/17


Support additional DM-RS port for higher order MU-MIMO

Support at most 8 layers MU-MIMO in Rel-13

12 DM-RS REs with OCC = 4 for up to total 4 layers per scrambling sequence

1 bit is add to DCI format 2C and 2D

One Codeword:

Codeword 0 enabled,

Codeword 1 disabled

Two Codewords:

Codeword 0 enabled,

Codeword 1 enabled

Value Message Value Message

0 1 layer, port 7, nSCID=0 (OCC=2) 0 2 layer, port 7-8, nSCID=0 (OCC=2)




4 1 layer, port 7, nSCID=0 (OCC=4) 4 2 layer, port 11,13, nSCID=0 (OCC=4)

5 1 layer, port 7, nSCID=1 (OCC=4) 5 2 layer, port 11,13, nSCID=1 (OCC=4)

6 1 layer, port 8, nSCID=0 (OCC=4) 6 3 layer, port 7-9




10 1 layer, port 13, nSCID=0 (OCC=4) 10 7 layers, ports 7-13

11 1 layer, port 13, nSCID=1 (OCC=4) 11 8 layers, ports 7-14

12 2 layers, ports 7-8 12 Reserved



15 Reserved 15 Reserved

One Codeword:

Codeword 0 enabled,

Codeword 1 disabled

Two Codewords:

Codeword 0 enabled,

Codeword 1 enabled

Value Message Value Message

0 1 layer, port 7, nSCID=0 0 2 layers, ports 7-8, nSCID=0

1 1 layer, port 7, nSCID=1 1 2 layers, ports 7-8, nSCID=1

2 1 layer, port 8, nSCID=0 2 3 layers, ports 7-9

3 1 layer, port 8, nSCID=1 3 4 layers, ports 7-10

4 2 layers, ports 7-8 4 5 layers, ports 7-11



7 Reserved 7 8 layers, ports 7-14

Rel-13 DMRS table

Ref: TS 36.212

Previous DMRS table

14/17


Improve SRS capacity:

Increasing the number of UpPTS SC-FDMA symbols utilized for SRS transmission

• Additional number of UpPTS symbol can be {2,4}

• Supported by CMCC

Increasing the number of SRS combs to 4

• Cyclic shift also increased from 8 to 12

• Supported by other TDD operators (e.g. Softbank)

15/17


Extend CSI-RS antenna port number up to 32

{20, 24, 28, 32} CSI-RS ports

Improve UE-specific beamformed CSI-RS

E.g. aperiodic CSI-RS

CSI reporting enhancement

New codebook design

Hybrid CSI-RS

• E.g. non-precoded & beamformed CSI reporting

Advanced CSI

• PMI enhancement (e.g. MU CSI, explicit feedback)

• CQI enhancement (e.g. MU CQI)

DM-RS based open-loop transmission

16/17


Recently, Massive MIMO is considered as one of the key technologies for further capacity enhancement

More suitable for higher frequency band

Challenges and research directions for mmWave Massive MIMO

Cost, Cost, and Cost

Channel modeling (on-going in 3GPP)

Coverage

User mobility

Interference management and spatial reuse

chih-hsuan chen chttl 2016/05/06 - 工研院資通所參與4g, 3gpp, ieee 802.16,lte...

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