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
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
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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
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Part 1:
A Review of MIMO Techniques in LTE
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Transmission Modes in LTE
M100/ICL 5
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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).
M100/ICL 6
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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.
M100/ICL 7
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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.
M100/ICL 8
CRS-based Precoding DMRS-based Precoding
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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
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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 .
M100/ICL 10
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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)
M100/ICL 11
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Part 2:
On-going Developments of
MIMO for 5G
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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.
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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.
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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/
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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.
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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.
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.
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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.
M100/ICL 18
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.
M100/ICL 19
Source: J. Jeganathan et al, “Generalized space shift keying modulation for MIMO channels”, IEEE PIMRC, Sept. 2008.
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Part 3:
Status of FD-MIMO
Standardization for LTE
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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
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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:
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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:
M100/ICL 23
Source:
R1-144190, “High Level View of Schemes for EBF/Full Dimension MIMO”, Nokia, 3GPP RAN1 #78bis
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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
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)
……
……
…
…
…
…
…
…
……
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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
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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
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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.
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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 ?
M100/ICL 28
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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
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
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Enhancements for Non-Precoded CSI-RS:
Reference Signal Resource (3/4)
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
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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 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
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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
M100/ICL 32
Source: 3GPP TR 36.987 – Study on EB/FD-MIMO for LTE
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Enhancements for Non-Precoded CSI-RS:
2D Codebook Design (2/5)
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.
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Enhancements for Non-Precoded CSI-RS:
2D Codebook Design (3/5)
M100/ICL 34
Source:
R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82
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.
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Enhancements for Non-Precoded CSI-RS:
2D Codebook Design (4/5)
M100/ICL 35
Source:
R1-155018, “WF on precoder and PMI construction for R13 FD-MIMO”, 3GPP RAN1 #82
Three design alternatives of :
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Enhancements for Non-Precoded CSI-RS:
2D Codebook Design (5/5)
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.
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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.
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
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Enhancements for Beamformed CSI-RS:
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
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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:
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
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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
M100/ICL 40
Source:
3GPP TR 36.987 – Study on EB/FD-MIMO for LTE
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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:
3GPP TR 36.987 – Study on EB/FD-MIMO for LTE
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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.
M100/ICL 42
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Appendix:
3GPP RAN1 #82 (Aug/2015)
Agreements on EB/FD-MIMO
Source:
3GPP RAN1 #82 (Beijing, China) Chairman’s Note
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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)
M100/ICL 44
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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
M100/ICL 45
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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
M100/ICL 46
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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
M100/ICL 47
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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
M100/ICL 48
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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
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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)
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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 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
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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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