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An overview of New 3GPP

RAN1 Features and FD-MIMO

Technologies for LTE

郭秉衡資深工程師

工研院資通所

新興無線技術應用組

October 4, 2015 1

Copyright 2015 ITRI 工業技術研究院

Outline

Introduction: An overview of RAN1 study/working items

in 3GPP LTE Rel-13

Part 1: A Review of MIMO Techniques in LTE

Part 2: On-Going Developments of MIMO for 5G

Part 3: Status of FD-MIMO Standardization for LTE

Two-Dimensional Antenna Array and Modeling

Enhancements Relating to Non-Precoded CSI-RS

Enhancements Relating to Beamformed CSI-RS

Others

Summary and Conclusion

M100/ICL 2


RAN1 Study/Working Items for Release 13

M100/ICL 3

Working Items:

Carrier Aggregation Enhancements (eCA)

Physical Layer Enhancements for MTC

Enhanced Device-to-Device Communications

Licensed-Assisted Access (LAA)

Elevation Beamforming and Full-Dimension(FD-) MIMO

Study Items:

Indoor Positioning Enhancements

Downlink Multi-User Superposition Transmission (MUST)

LTE-based V2X Services

Copyright 2015 ITRI 工業技術研究院 M100/ICL 4

Part 1:

A Review of MIMO Techniques in LTE


Transmission Modes in LTE

M100/ICL 5


Closed-Loop Spatial Multiplexing

Spatial multiplexing allows joint transmission of multiple data layers in the

same time-frequency resource, in order to increase the system peak rate.

With closed-loop operation, the UE should measure the instantaneous channel

state information (CSI) and reports the following to the eNodeB:

The number spatial layers that can be jointly transmitted (RI).

A selection (from a pre-defined codebook) of precoding matrix (PMI).

A recommendation on modulation and coding scheme that reflects channel

quality (CQI).

M100/ICL 6


Multi-User MIMO

Spatial Multiplexing can be extended to serve multiple users in the same

radio resource block via spatial separation.

Performance of MU-MIMO can be affected by many factors:

User pairing and channel orthogonality.

Multi-user diversity.

Accuracy of PMI/CQI reports.

Precoder construction can be either transparent or non-transparent

(e.g. zero-forcing beamforming) to UEs, depending on the TM.

M100/ICL 7


Downlink Reference Signals in LTE

Cell-Specific Reference Signals (CRS)

Cell-wide coverage – can be detected by all users within the cell.

Mai ly used for ell sele tio a d de odulatio of asi sig als.

DeModulation Reference Signals (DMRS)

Associated with data (PDSCH) signals.

Precoded prior to transmission – allowing UE-transparent precoding.

Channel State Information Reference Signals (CSI-RS)

UE-specific configured resources.

Mainly used for CSI measurements.

M100/ICL 8

CRS-based Precoding DMRS-based Precoding


Dual-Codebook Structure (1/2)

TM9 of LTE enables spatial multiplexing of up to 8 layers. A dual-

codebook structure has been adopted for this TM to:

Reduce the potential feedback overheads for larger antenna arrays such as 8-TX.

Capture the characteristic of cross-polarization antennas.

The precoder based on dual-codebook structure can be expressed as:

W1 : A wideband PMI that represents long-term statistics of channel such as a

cluster of beam directions

W2 : A subband PMI that performs beam selection for each polarization group and

co-phasing between polarizations.

M100/ICL 9


Dual-Codebook Structure (2/2)

Mathematically, W1 is a block diagonal matrix, where each sub-matrix

(corresponding to each polarization)is consisted of multiple DFT vectors

representing beam directions. W2 is formed by at least one vectors each with

only two non-zero entries.

This approa h a e visualized as grid-of- ea s .

M100/ICL 10


Coordinate Multi-Points (CoMP)

Three categories of CoMP schemes:

Coordinated Scheduling / Coordinated Beamforming (CS/CB)

Joint Transmission (JT)

Dynamic Point Selection (DPS)

M100/ICL 11


Part 2:

On-going Developments of

MIMO for 5G


Massive-MIMO (1/2)

M100/ICL 13

Research in recent years have shown great potentials of MIMO systems

equipping with a large number of antennas. This new paradigm dubbed as

Massive-MIMO has ee regarded as o e of the key a didate technologies for 5G.

Benefits of Massive-MIMO:

– Energy efficiency

– High spatial-multiplexing gain

(for MU-MIMO)

– Eliminating of fading effects and

noise asymptotically

– Channel hardening

Challenges of Massive-MIMO:

– CSI acquisition in FDD mode

– Pilot contamination

Source: E. G. Larsson, F. Tufvesson, O. Edfors, and T. L. Marzetta, Massive MIMO for Next Generation Wireless Systems, IEEE Commun. Mag., vol. 52, no. 2, pp. 186-195, Feb. 2014.


Massive-MIMO (2/2)

M100/ICL 14

Massive-MIMO is able to achieve better system performance under the same

regulatory power constraints, as energy can be more focused. This also

reduces interference leakage to the other receivers nearby.

Inter-cell interference caused by pilot contamination is a potential limitation

for massive-MIMO systems, as well as a very hot research topic in academia.

Training (Uplink) Transmission (Downlink)

Source: F. Rusek et al, ”Scaling up MIMO: Opportunities and Challenges with Very Large Arrays”, IEEE Signal Proces. Mag., vol. 30, no. 1, pp. 40-46, Jan. 2013.


Millimeter Wave (mmWave) Massive-MIMO (1/2)

M100/ICL 15

In order to cope with the ever-increasing demand of mobile data traffic,

feasibility of cellular communications at mmWave frequencies, where a vast

amount of unlicensed spectrum is available, is being intensively studied as a

potential enabling technology of 5G.

Source: http://news.mynavi.jp/news/2014/05/09/070/


Millimeter Wave (mmWave) Massive-MIMO (2/2)

M100/ICL 16

Traditionally, path loss is believed to be much more severe in

propagation at mmWave frequencies, as compared to microwave.

However, the achievable range of transmission at higher frequencies is

in fact longer if directive beamforming is applied.

mmWave + Massive-MIMO is a promising approach!

Transceiver architecture based on hybrid analog/digital beamforming

has been proposed as a more cost-effective solution.

Source: W. Roh et al, “Millimeter-Wave Beamforming as an Enabling Technology for 5G Cellular Communications: Theoretical Feasibility and Prototype Results”, IEEE Communications Mag., Feb., 2014, pp. 106-113.


Cooperative MIMO in Cloud-RAN

With Cloud-RAN, baseband processing of multiple remote radio heads (RRHs) is

carried out at a central unit, and cooperative MIMO transmission by multiple

geographically separated RRHs is hence easier than conventional CoMP

schemes.

M100/ICL 17

Cooperative MIMO

Source: S. Park, C.-B. Chae and S. Bahk, “Large Scale Antenna Operation in Heterogeneous Cloud Radio Access Network: A Partial Centralized Approach”, IEEE Wireless Communications, June 2015, pp. 32-40.


Antenna Index Modulation (1/2)

Spatial Modulation (SM)

The data stream is partitioned into two parts. The first part is encoded with

the index of the only one activated transmit antenna, while the second part

is carried using conventional IQ-signal.

M100/ICL 18

Source: R. Y. Mesleh et al, “Spatial Modulation”, IEEE Trans. Veh. Tech, Vol. 57, July 2008, pp. 2228-2241.


Antenna Index Modulation (2/2)

Generalized Space Shift Keying (GSSK)

Information is conveyed merely with the indices combinations of activated

antennas.

M100/ICL 19

Source: J. Jeganathan et al, “Generalized space shift keying modulation for MIMO channels”, IEEE PIMRC, Sept. 2008.


Part 3:

Status of FD-MIMO

Standardization for LTE


Introduction to FD-MIMO (1/2)

M100/ICL 21

FD-MIMO is a special case of Massive-MIMO in 3GPP LTE-A with:

Two-dimensional rectangular antenna array

The number of antenna ports for 2D arrays can be 8, 12, or 16.

Beams can be steered in both azimuth and elevation dimensions, so

more users can be co-scheduled in MU-MIMO operation.

2D X-Pol Antenna Array


Introduction to FD-MIMO (2/2)

M100/ICL 22

Conventional MIMO or BF in

horizontal direction

FD-MIMO for single UE in

horizontal/vertical direction

FD-MIMO for multiple UEs in

horizontal/vertical direction

Source:

R1-143883, “High-level views on FD-MIMO and elevation beamforming”, Samsung, 3GPP RAN1 #78bis

An illustrative comparison between conventional MIMO and FD-

MIMO:


Standard-Transparent Approach:

Vertical Sectorization

An standard-transparent way to utilize 2D antenna array:

Assigning beams of different elevation angles with different

physical cell IDs:

M100/ICL 23

Source:

R1-144190, “High Level View of Schemes for EBF/Full Dimension MIMO”, Nokia, 3GPP RAN1 #78bis


2D Antenna Array Model

The configuration of a 2D planar uniformly spaced antenna array model is represented by (M, N, P):

M is the number of antenna elements with the same polarization in each

column.

N is the number of columns and

P is the number of polarization dimensions

M100/ICL 24

(0,0) (0,1) (0,N-1)

(M-1,N-1)

……

(M-1,0) (M-1,1)

(1,0) (1,1) (1,N-1)

……

……

…

…

…

…

…

…

……


Signal Processing Model

M100/ICL 25

Baseband processor

Virtualization matrix

X

(port-to-TXRU)

Virtualization matrix

Y

(TXRU-to-antenna elements)

NAP

ports

NU

TXRUs

NT

antenna elements

...

...

...

TXRU

TXRU

TXRU

Source:

R1-144047, “RS design enhancements for supporting EB and FD-MIMO”, LG Electronics, 3GPP RAN1 #78bis

How signals on logical links (antenna ports) are mapped to

physical antenna elements:

Port Virtualization TXRU Virtualization


TXRU Virtualization Models

M100/ICL 26

TXRU

TXRU

M

K

w1

w2

w3

w4

m'=1

m'=2

x q

w

M

+

+

+

+

+

+

+

+

TXRUm'=1

TXRUm'=2

w1,1

x q

W

Sub-Array Model Full-Connection Model

Source:

3GPP TR 36.987 – Study on EB/FD-MIMO for LTE


CSI-RS Ports Virtualization

M100/ICL 27

Category 1: Non-Precoded CSI-RS

-Wide cellular coverage Reference

signals

-The number of antenna ports can be larger than 8.

Category 2: Beamformed CSI-RS

-Narrow Beam Reference signals

-The number of antenna ports is

smaller or equal to 8.


Enhancements for Non-Precoded CSI-RS:

Reference Signal Resource (1/4)

Reference Signals Enhancements:

Extending the existing numbers {1,2,4,8} of CSI-RS antenna ports for support

of 12 and 16 CSI-RS ports, using full-port mapping.

Currently, only CSI-RS patterns for {1, 2, 4, 8} ports are available in LTE:

How do configure CSI-RS resources with more than 8 ports ?

M100/ICL 28




A few different alternatives have been proposed, including:

TDM-based approach

M100/ICL 29

PDCCH R8 - DMRS Port 5 if configuredPDSCH CRS Port 0,1 CRS Port 2,3 R9/10 - DMRS Port7-10

9

13

11

15

8

12

10

14

131211109876543210131211109876543210

1

5

3

7

0

4

2

6

Subframe m Subframe n

Source:

R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82

time




FDM-based approach

M100/ICL 30

Source: R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82

PDCCH

R8 - DMRS Port 5 if configured

PDSCH CRS Port 0,1

CRS Port 2,3 R9/10 - DMRS Port7-10

9

13

11

15

8

12

10

14

131211109876543210

131211109876543210

1

5

3

7

0

4

2

6

Frequency




Single-PRB approach – CSI-RS Aggregation

E.g. 16-ports CSI-RS can be formed by aggregating two 8-ports CSI-RS within the

same PRB/subframe.

E.g. 12-ports CSI-RS can be formed by aggregating one 8-port CSI-RS and one 4-

ports CSI-RS within the same PRB/subframe.

M100/ICL 31

Source:

R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82



2D Codebook Design (1/5)

Codebook Enhancements:

The precoder codebook for 2D antenna arrays for support of {8,12,16} CSI-

RS ports and associated necessary channel state information.

Each precoding matrix or vector within a codebook for CSI reporting can be described as W = W1W2 where W is used as a downlink transmission

hypothesis for CSI calculation at a UE. For this dual-stage precoding structure, a potential specification enhancement on CSI reporting consists of the following CSI parameters:

PMI(s) corresponding to W1 and/or W2. Here one or multiple PMIs, such as

H-PMI (horizontal dimension) and V-PMI (vertical dimension), are reported for W1 and W2, respectively. If multiple PMIs are reported, different reporting

rates and/or granularities for different PMIs may or may not be used, and each of these PMIs can be reported either periodically or aperiodically.

RI: a single RI or multiple RIs

CQI

M100/ICL 32

Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE




M100/ICL 33

Source:

R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82

In general, the codebook-based precoder structure for 2D array can be written as:

where constructs grid-of-beams

and is used for beam selection(s) out of and co-phasing.

X1 is a N1xL1 matrix with L1 column vectors being an O1 times

oversampled DFT vector of length N1.

X2 is a N2xL2 matrix with L2 column vectors being an O2 times

oversampled DFT vector of length N2.

N1 and N2 are the numbers of antenna ports per pol in 1st and 2nd dimensions.




M100/ICL 34

Source:


Note that Xi (i = 1, 2) represents a beam subset for each of the two dimensions (horizontal and vertical) of the antenna array, where the i-th

dimension of the array has Ni (i = 1, 2) antenna ports per polarization.

Each column of X1 can be written as

Similarly, each column of X2 can be written as

where l is the beam index within a beam group.




M100/ICL 35

Source:


Three design alternatives of :




M100/ICL 36

Source:

R1-153168, “2D Codebook with KP structure and associated feedback”, Ericsson, 3GPP RAN1 #81

We may have different 2D antenna ports layouts with different antenna configurations:

A parameterized scalable codebook could be a “one-for-all” solution wherein the configurations of Ni (i = 1, 2) are signaled by the network.


Enhancements for Beamformed CSI-RS:

Beam Selection (1/2)

With Beamformed CSI-RS, the UE should measure channel state information (CSI) on CSI-RS resources that are beamformed toward different directions.

A potential enhancement is the introduction of “beam index” reporting to LTE specification.

M100/ICL 37

Channel estimation

Channel estimation

Channel estimation

Channel estimation

RI, PMI, CQI

RI, PMI, CQI

RI, PMI, CQI

RI, PMI, CQI

Beam selection

according to CSIs

Source:

R1-151983, “Enhanced precoding schemes for elevation beamforming and FD-

MIMO”,NTT Docomo, 3GPP RAN1 #80bis



Beam Selection (2/2)

M100/ICL 38

OFDM symbols

Sub

carr

iers

Beam 1

CSI-RS Resource

Beam 2

CSI-RS Resource

Beam 3

CSI-RS Resource



Measurement Restriction

Conventionally, the UE can derive channel state information (CSI) by averaging over measurements of CSI-RS in multiple subframes.

In Rel-13, CSI-RS transmission could be beamformed to different directions in consecutive subframes:

Rel-13 aims to provide eNodeB the capability to configure the number of

subframes that the UE should use to derive CSI to ensure accuracy.

M100/ICL 39

Subframe 1 Subframe 2

Subframe 3 Subframe 4

CSI-RS

Beam

CSI-RS

Beam

CSI-RS

Beam CSI-RS

Beam


Other Enhancements:

Sounding Reference Signals (SRS)

SRS capacity improvement:

the following schemes can be considered:

Transmitting SRS on unused PUSCH DMRS resources

Transmitting SRS on PUSCH resources

Increasing the number of SRS combs

4Tx antenna switching for SRS transmission

Precoded SRS

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

M100/ICL 40

Source:



Other Enhancements:

DeModulation Reference Signals (DMRS)

Support of additional ports for DMRS targeting higher dimensional MU-MIMO:

Alternative 1: 12 DM-RS REs with OCC = 4 for up to total 4 layers per scrambling sequence, This alternative allows up to total 4 layers per

scrambling sequence

Alternative 2: 24 DM-RS REs with OCC = 2 for up to total 4 layers per

scrambling sequence, This alternative allows up to total 4 layers per

scrambling sequence

Alternative 3: 24 DM-RS REs with OCC = 4 for up to total 8 layers per

scrambling sequence, This alternative allows up to total 8 layers per

scrambling sequence

Alternative 4: DM-RS estimation accuracy improvement by advanced receiver assuming interference channel estimation

Alternative 5: Larger PRG size

M100/ICL 41

Source:



Summary and Conclusions

Part 1: A Review of MIMO Techniques in LTE:

MIMO technology has been a key feature to achieve high peak data throughput in

4G LTE systems.

Part 2: On-Going Developments of MIMO for 5G:

Massive-MIMO is a promising approach to further improve spectral efficiency for

5G.

CSI acquisition mechanisms, or the schemes without CSI at transmitter side, should

be developed for massive-MIMO.

Massive-MIMO is particularly useful at mmWave frequencies.

Distributed and cooperative MIMO may play critical roles in future RAN topologies.

Part 3: Status of FD-MIMO Standardization for LTE :

A preliminary special version of massive-MIMO dubbed as FD-MIMO is currently

being standardized in 3GPP LTE Rel-13, which features 2D antenna arrays.

The category of Non-Precoded CSI-RS requires new design of reference signals and

precoder codebook to accommodate 12 and 16 antenna ports.

The category of Beamformed CSI-RS requires new feedback mechanism for beam

index selection.

M100/ICL 42


Appendix:

3GPP RAN1 #82 (Aug/2015)

Agreements on EB/FD-MIMO

Source:

3GPP RAN1 #82 (Beijing, China) Chairman’s Note


CSI Reporting Class A and B (1/2)

Agreements:

CSI reporting with PMI

A CSI process can be configured with either of two CSI reporting classes, A

or B (FFS: both A and B):

Class A, UE reports CSI according to W=W1W2 codebook based on {[8],12,16}

CSI-RS ports

Class B: UE reports L port CSI assuming one of the four alternatives below

Alt.1: Indicator for beam selection and L-port CQI/PMI/RI for the selected

beam. Total configured number of ports across all CSI-RS resources in the

CSI process is larger than L.

Alt.2: L-port precoder from a codebook reflecting both beam selection(s) and

co-phasing across two polarizations jointly. Total configured number of ports

in the CSI process is L.

Alt.3: Codebook reflecting beam selection and L-port CSI for the selected

beam. Total configured number of ports across all CSI-RS resources in the

CSI process is larger than L.

Alt.4: L-port CQI/PMI/RI. Total configured number of ports in the CSI process

is L. (if CSI measurement restriction is supported, it is always configured)

M100/ICL 44


CSI Reporting Class A and B (2/2)

Note: A “beam selection” (whenever applicable) constitutes either a selection of a subset of antenna ports within a single CSI-RS resource or

a selection of a CSI-RS resource from a set of resources

Note: The reported CSI may be an extension of Rel.12 L-port CSI

Details such as possible values of L are FFS

Further down-selection/merging of the four alternatives is FFS

M100/ICL 45


More Details on Reporting Class B (1/3)

Agreements:

For alternatives 1, 2, 3, and 4 of CSI reporting class B,

Nk {1,2,4,8}

For Alt.1, UE reports L port CSI assuming either one of the followings

L = Nk

L (<= Nk) which can be configured or fixed in spec.

For Alt.2, two possible schemes:

UE reports L port CSI assuming L = sum(Nk) for all k;

UE reports L port CSI where K is always equal to 1 (L = N1)

For Alt.3, UE reports L port CSI assuming either one of the followings

L = Nk

L (<= Nk) which can be configured or fixed in spec.

For Alt.4, UE reports L port CSI assuming L = Nk

M100/ICL 46


More details on Reporting Class B (2/3)

Agreements:

Study the following aspects for CSI-process reporting class B, including but

not limited to

Number of antenna ports L for CSI (e.g., 2, 4, 8)

Class B Alt-1:

Beam selection indicator (BI) definition, e.g. RSRP or CSI based, wideband vs.

subband, short-term vs. long-term

BI bitwidth (related to K)

Support for rank>2 UE specific beamforming

UCI feedback mechanisms on PUCCH/PUSCH

Class B Alt-3:

Codebook for beam selection and CSI

PMI contains the information of selected beam and the precoding matrix for the L-port within the selected beam


M100/ICL 47


More details on Reporting Class B (3/3)

Class B Alt-2:

Codebook for beam selection and co-phasing (either derived from legacy

codebook(s) or codebook components, or newly designed)

Along with the associated PMI (e.g. assuming W = W2 in the newly designed or legacy codebook)


Class B Alt-4:

Measurement restriction mechanism; may be also applicable to Alt-1 to 3.

Other aspects not precluded

M100/ICL 48


CSI Process and CSI-RS Resource (1/2)

Agreements:

A CSI process is associated with K CSI-RS resources/configurations (per

definition in 36.211), with Nk ports for the kth CSI-RS resource (K could be

>=1)

Note: it is up to RAN2 to design the signaling configuration structure to support the

above association

Maximum value of K is FFS

Maximum total number of CSI-RS ports in one CSI process

For CSI reporting class A, the Maximum total number of CSI-RS ports is 16

FFS the maximum total number of CSI-RS ports in one CSI process is for CSI reporting class B

For the purpose of RRC configuration of CSI-RS resource/configuration

For CSI reporting Class A, RAN1 will choose one of the alternatives

» Alt.1: CSI-RS resource/configuration with Nk: =12/16 to be defined in the spec (The index of CSI-RS configuration can be configured for CSI process with K=1).

» Alt.2: 12/16 ports CSI-RS is an aggregation of K configured CSI-RS resources/configurations with 2/4/8 ports. (K>1)

FFS on the schemes for aggregation and port indexing

FFS between fixed or configurable value(s) for Nk

For CSI reporting class B, FFS for details

M100/ICL 49


CSI Process and CSI-RS Resource (2/2)

Note: It is possible to extend the value of Nk: in future releases

FFS by RAN1 on the configuration restriction of using same CSI-RS

resource/configuration parameters within one CSI process (e.g. Nk , Pc, CSR, scrambling ID, subframe config., etc.)

FFS on the QCL on CSI-RS ports

Inform RAN2 about the above decision to start RRC signaling structure discussion

M100/ICL 50


CSI-IM Configurations

Agreements:

For CSI reporting classes A and B (If CSI-IM is supported and used)

On the CSI-IM association with CSI process and CSI resource/configuration, RAN1 will down-select between the following two alternatives:

Alt.1: A CSI process is associated with one CSI-IM (common interference

measurement resource across all CSI resources/configurations within a CSI

process)

Alt.2: A CSI process can be associated with multiple CSI-IM

RRC signaling framework should support different CSI resource/configuration to be associated with different CSI-IM resource configuration.

CSI-IM resource configuration is at least supported as Rel.12 legacy

FFS: Change on CSI-IM resource configuration

M100/ICL 51


CSI Measurement Restriction (1/4)

M100/ICL 52

Agreed definition for further study/evaluation

For a given CSI process, if MR on channel measurement is ON, then the

channel used for CSI computation can be estimated from X NZP CSI-RS subframe(s) up until and including CSI reference resource

Channel measurement is derived from NZP CSI-RS

FFS on MR based on L1 triggering and/or higher-layer signaling for dynamic CSI

request

Depending on the chosen scheme, X can be either explicitly configured or selected

by the UE between 1 and ZX

For a given CSI process with CSI-IM(s), if MR on interference measurement

is ON, then the interference used for CSI computation can be estimated from

Y CSI-IM subframe(s) up until and including CSI reference resource

Interference measurement is derived from CSI-IM

FFS on MR based on L1 triggering and/or higher-layer signaling for dynamic CSI

request

Depending on the chosen scheme, Y can be either explicitly configured or selected

by the UE between 1 and ZY



If a CSI process can be configured without CSI-IM, for a given CSI process

without CSI-IM(s), if MR on interference measurement is ON, then

interference used for CSI computation can be estimated from V subframe(s) up until and including CSI reference resource

For a given CSI process, MR may be higher-layer configured for both

channel and interference

MR for channel and interference can be configured independently

Note: Channel and interference MR are considered independently

Note: Interference measurement restriction for CSI processes configured with

CSI-IM or without CSI-IM can be considered, independently

Interaction with other features (e.g. eIMTA, FeICIC, COMP) is FFS

M100/ICL 53



Agreements on alternative schemes:

Alt.1: Fixed MR ON or OFF via higher-layer configuration

X/Y are fixed to a single value respectively in specification

Alt.2: Configurable MR ON or OFF via higher-layer configuration

X={OFF, 1, … , NX} are higher-layer configurable

Y={OFF, 1, … , NY} are higher-layer configurable

Alt.3: CSI measurement is periodically reset

Reset period and subframe offset are higher-layer configured

Note: X is selected by the UE between 1 and ZX where ZX is the number of CSI-RS subframes between the latest measurement reset and the CSI reference resource.

Note: Y is selected by the UE between 1 and ZY where ZY is the number of CSI-IM subframes between the latest measurement reset and the CSI reference resource.

Note that other alternatives are not precluded

M100/ICL 54



Conclusion:

Continue discussion until RAN1 #82bis meeting about necessity for channel

and interference MR

Note: Needs for channel and interference MR are considered independently

M100/ICL 55


Non-precoded CSI-RS For 12 and 16 ports

Agreements:

Design principle for 12- and 16-port NZP CSI-RS resources in Rel-13:

CSI-RS density of 1RE/RB/port is maintained

FFS on lower density

Only existing 40 CSI-RS REs per PRB pair are reused for 12- and 16-port NZP

CSI-RS resources

12- or 16-port NZP CSI-RS REs are obtained by aggregating NZP CSI-RS REs of

multiple legacy CSI-RS configurations in the same subframe

FFS on configuration details

FFS on CDM length

FFS on improvement of 12-port NZP CSI-RS resources using REs other than

existing 40 CSI-RS REs

FFS on CSI-RS transmission in DwPTS

M100/ICL 56


SRS capacity improvement

Agreement:

Specify at least the following SRS capacity enhancements in Rel-13:

Increase the number of UpPTS SC-FDMA symbols for SRS

Working Assumption:

Increase number of combs to 4

FFS: Max number of CS

Other enhancement techniques that have been studied in the SI or submitted at RAN1#82 can also be discussed at RAN1#82bis.

M100/ICL 57


Additional DMRS ports

Working Assumption, subject to resolution of signalling and power

imbalance issues:

Alt.1, i.e., OCC=4 and 12REs for higher order MU-MIMO transmission is supported with the following ports

Solutions for signalling and power imbalance should be submitted for RAN1#82bis.

M100/ICL 58


CSI Reporting Types and Reporting Modes (1/3)

Agreements:

For Rel. 13 EB/FD-MIMO,

Notify RAN2 a summary of the contents of the following slides

Note: CSI reporting mode is only associated with frequency granularity of

CQI and PMI

Specify extension of Rel.12 PUSCH based A-CSI reporting modes for FD-

MIMO as follows:

Supported A-CSI modes with PMI are the existing Rel.12 modes :

1-2, 2-2, 3-1, and 3-2

Content of A-CSI reporting may depend on codebook-related parameters and CSI

reporting class

CQI, RI, PMI reported according to CSI reporting mode definition

• Size of base CQI and RI remains the same as Rel.12

• Note: Base CQI size per CW is 4 bits

• Exact PMI size and contents for class A is FFS

• Exact PMI size and contents and/or beam selection indication for class B FFS

• Details on additional CSI parameters (if supported) for class A and B are FFS

M100/ICL 59



RRC configuration details of these modes are FFS

Specify extension of Rel.12 PUCCH based P-CSI reporting modes for FD-

MIMO as follows:

Supported P-CSI modes with PMI are the existing Rel.12 modes:

1-1, 2-1

» Submodes of mode 1-1 (if any) FFS

Content of P-CSI reporting may depend on the submode (if any), codebook-

related parameters and CSI reporting class

CQI, RI, PMI reported according to CSI reporting mode definition

• Size of base CQI and RI remains the same as Rel.12

• Note: Base CQI size per CW is 4 bits

• Exact PMI size and contents for class A is FFS

• Exact PMI size and contents and/or beam selection indication for class B FFS

• Details on additional CSI parameters (if supported) for class A and B are FFS

New CSI reporting types are possible

RRC configuration details of these modes are FFS

Rel. 12 CSI reporting modes without PMI are by default supported

FFS: Enhancement for Rel. 13

M100/ICL 60



CSI reporting without PMI for Rel.13 FD-MIMO

Companies are encouraged to study further of CSI reporting without PMI

M100/ICL 61

The End

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