An Overview Of Fd-mimo Technologies For Lte.pdf

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

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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

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RAN1 Study/Working Items for Release 13  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

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Part 1: A Review of MIMO Techniques in LTE

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Transmission Modes in LTE

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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).

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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.

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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.

CRS-based Precoding Copyright 2015 ITRI 工業技術研究院

DMRS-based Precoding M100/ICL

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Dual-Codebook Structure (1/2)  TM9 of LTE enables spatial multiplexing of up to 8 layers. A dualcodebook 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.

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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 .

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Coordinate Multi-Points (CoMP)  Three categories of CoMP schemes:  Coordinated Scheduling / Coordinated Beamforming (CS/CB)  Joint Transmission (JT)  Dynamic Point Selection (DPS)

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

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Massive-MIMO (1/2)  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. Copyright 2015 ITRI 工業技術研究院

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Massive-MIMO (2/2)  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.

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.

 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) Copyright 2015 ITRI 工業技術研究院

Transmission (Downlink) M100/ICL

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Millimeter Wave (mmWave) Massive-MIMO (1/2)  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/ Copyright 2015 ITRI 工業技術研究院

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Millimeter Wave (mmWave) Massive-MIMO (2/2)  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. Copyright 2015 ITRI 工業技術研究院

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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. 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. Copyright 2015 ITRI 工業技術研究院

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

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Antenna Index Modulation (2/2)  Generalized Space Shift Keying (GSSK)  Information is conveyed merely with the indices combinations of activated

antennas.

Source: J. Jeganathan et al, “Generalized space shift keying modulation for MIMO channels”, IEEE PIMRC, Sept. 2008. Copyright 2015 ITRI 工業技術研究院

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Part 3: Status of FD-MIMO Standardization for LTE

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Introduction to FD-MIMO (1/2)  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

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Introduction to FD-MIMO (2/2)  An illustrative comparison between conventional MIMO and FDMIMO: 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 Copyright 2015 ITRI 工業技術研究院

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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:

Source: R1-144190, “High Level View of Schemes for EBF/Full Dimension MIMO”, Nokia, 3GPP RAN1 #78bis Copyright 2015 ITRI 工業技術研究院

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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 …… (M-1,N-1)

……

……

……

……

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

…… (1,0)

(1,1)

(1,N-1)

…… (0,0) Copyright 2015 ITRI 工業技術研究院

(0,1)

(0,N-1) M100/ICL

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Signal Processing Model  How signals on logical links (antenna ports) are mapped to physical antenna elements: Baseband processor

TXRU NU TXRUs

NAP ports

Port Virtualization

Virtualization matrix Y (TXRU-to-antenna elements)

...

...

...

Virtualization matrix X (port-to-TXRU)

TXRU TXRU

NT antenna elements

TXRU Virtualization

Source: R1-144047, “RS design enhancements for supporting EB and FD-MIMO”, LG Electronics, 3GPP RAN1 #78bis Copyright 2015 ITRI 工業技術研究院

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TXRU Virtualization Models w

W

w1

w1,1

+

w2 TXRU

m'=1 w3

TXRU

K

m'=1

+

+

w4

x

q

x

M

+

q

+

TXRU

m'=2 TXRU

m'=2

+ + +

Sub-Array Model

Full-Connection Model

Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE Copyright 2015 ITRI 工業技術研究院

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M

CSI-RS Ports Virtualization

Category 1: Non-Precoded CSI-RS

Category 2: Beamformed CSI-RS

-Wide cellular coverage Reference signals -The number of antenna ports can be larger than 8.

-Narrow Beam Reference signals -The number of antenna ports is smaller or equal to 8.

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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 ? Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: Reference Signal Resource (2/4)  A few different alternatives have been proposed, including:  TDM-based approach Subframe m 0

1

2

3

4

7

8

Subframe n

5

6

0 4

1 5

8 9 12 13

2 6

3 7

10 11 14 15

PDCCH

9

10 11 12 13

PDSCH

CRS Port 0,1

0

CRS Port 2,3

1

2

3

R9/10 - DMRS Port7-10

4

5

6

7

8

9

10 11 12 13

R8 - DMRS Port 5 if configured

time

Source: R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82 Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: Reference Signal Resource (3/4)  FDM-based approach

Frequency

0

0

1

1

2

2

3

3

4

4

5

6

0 4

1 5

2 6

3 7

5

6

7

8

9 10 11 12 13

7

8

9 10 11 12 13

8 9 12 13

10 11 14 15

PDCCH

PDSCH

CRS Port 0,1

CRS Port 2,3 R9/10 - DMRS Port7-10 R8 - DMRS Port 5 if configured Source: R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82

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Enhancements for Non-Precoded CSI-RS: Reference Signal Resource (4/4)  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 4ports CSI-RS within the same PRB/subframe.

Source: R1-153792, “CSI-RS design for 12 and 16 ports”,Huawei/HiSilicon, 3GPP RAN1 #82 Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: 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 Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: 2D Codebook Design (2/5)  In general, the codebook-based precoder structure for 2D array can be written as:

where

and

constructs grid-of-beams

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. Source: R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82 Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: 2D Codebook Design (3/5)  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.

Source: R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82 Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: 2D Codebook Design (4/5)  Three design alternatives of

:

Source: R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82 Copyright 2015 ITRI 工業技術研究院

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Enhancements for Non-Precoded CSI-RS: 2D Codebook Design (5/5)  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. Source: R1-153168, “2D Codebook with KP structure and associated feedback”, Ericsson, 3GPP RAN1 #81 Copyright 2015 ITRI 工業技術研究院

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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.

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 FDMIMO”,NTT Docomo, 3GPP RAN1 #80bis Copyright 2015 ITRI 工業技術研究院

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Enhancements for Beamformed CSI-RS: Beam Selection (2/2) Beam 1 CSI-RS Resource

Subcarriers

Beam 2 CSI-RS Resource

Beam 3 CSI-RS Resource

OFDM symbols Copyright 2015 ITRI 工業技術研究院

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Enhancements for Beamformed CSI-RS: 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: Subframe 1

Subframe 2

Subframe 3

CSI-RS Beam

CSI-RS Beam

CSI-RS Beam

Subframe 4

CSI-RS Beam

 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.

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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

Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE Copyright 2015 ITRI 工業技術研究院

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Other Enhancements: DeModulation Reference Signals (DMRS)  Support of additional ports for DMRS targeting higher dimensional MUMIMO:  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

Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE Copyright 2015 ITRI 工業技術研究院

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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. Copyright 2015 ITRI 工業技術研究院

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Appendix: 3GPP RAN1 #82 (Aug/2015) Agreements on EB/FD-MIMO

Source: 3GPP RAN1 #82 (Beijing, China) Chairman’s Note Copyright 2015 ITRI 工業技術研究院

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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)

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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

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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

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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  UCI feedback mechanisms on PUCCH/PUSCH

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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)  UCI feedback mechanisms on PUCCH/PUSCH

 Class B Alt-4:  Measurement restriction mechanism; may be also applicable to Alt-1 to 3.

 Other aspects not precluded

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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 Copyright 2015 ITRI 工業技術研究院

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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

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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

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CSI Measurement Restriction (1/4)  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

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CSI Measurement Restriction (2/4)  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

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CSI Measurement Restriction (3/4)  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

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CSI Measurement Restriction (4/4)  Conclusion:  Continue discussion until RAN1 #82bis meeting about necessity for channel

and interference MR  Note: Needs for channel and interference MR are considered independently

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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

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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.

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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.

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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 FDMIMO 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

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CSI Reporting Types and Reporting Modes (2/3)  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

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CSI Reporting Types and Reporting Modes (3/3)  CSI reporting without PMI for Rel.13 FD-MIMO  Companies are encouraged to study further of CSI reporting without PMI

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The End

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