lte advanced

LTE-Advanced
October 2011
Bong Youl (Brian) Cho, 조 봉 열
brian.cho@nsn.com

TTA LTE/MIMO Standards/Technology Training
2 © Nokia Siemens Networks
Contents
• Beyond R8 LTE Standardization
• LTE-Advanced Technologies
• SON
• Long Term HSPA Evolution (LTHE)

Beyond R8 LTE Standardization

Release of 3GPP specifications
1999 2000 2001 2002 2003 2004 2005
Release 99
Release 4
Release 5
Release 6
1.28Mcps TDD
HSDPA, IMS
W-CDMA
HSUPA, MBMS, IMS+
2006 2007 2008 2009
Release 7 HSPA+ (MIMO, HOM etc.)
Release 8
2010 2011
LTE, SAE
ITU-R M.1457
IMT-2000 Recommendations
Release 9
LTE-AdvancedRelease 10
GSM/GPRS/EDGE enhancements
Small LTE/SAE
enhancements

Definition
• What is IMT-Advanced?
– A family of radio access technologies fulfilling IMT-Advanced requirements
– Relates to 4G as IMT-2000 relates to 3G
– IMT spectrum will be available to both IMT-2000 and IMT-Advanced
• What is LTE-Advanced?
– Formal name: Advanced E-UTRA /Advanced E-UTRAN
– Evolution from 3GPP LTE specifications, not a revolution
 Comparable potential of 3GPP LTE with target requirements of IMT-advanced
 Fast and efficient correspondence against the timeline of WP5D’s specification and
commercialization for IMT-advanced
 Cost-efficient support for backward and forward compatibility between LTE and
LTE-A
 Natural evolution of LTE (LTE release 10 & beyond)

System
Performance
IMT-Advanced requirements
and time plan
Rel. 8 LTE
LTE-Advanced
targets
Time
General Requirements for LTE-Adv
• LTE-Advanced is an evolution of LTE
• LTE-Advanced shall meet or exceed IMT-Advanced requirements within the
ITU-R time plan
• Extended LTE-Advanced targets are adopted
• LTE-Advanced will be deployed as an evolution of LTE R8 and on new bands.
• LTE-Advanced shall be backwards compatible with LTE R8 in the sense that
– an LTE Release 8 terminal can work in an LTE-Advanced NW
– an LTE-Advanced terminal can work in an LTE Release 8 NW

• Comparison b/w IMT-Advanced and LTE-Advanced
System Performance Requirements

System Performance Requirements
• Average Spectral Efficiency (SE) and Edge Spectral Efficiency for LTE
Case-1
 40~60% improvement of average spectrum efficiency over LTE Rel-8

Release 9
• Enhanced Home NodeB / eNodeB
• Support for IMS Emergency Calls over LTE
• LCS for LTE and EPS
• MBMS support in EPS
• Enhanced Dual-Layer transmission for LTE
• SON
• Deleted - Support of WiMAX - LTE Mobility
• Deleted - Support of WiMAX - UMTS Mobility

Release 10
• Network Improvements for Machine-Type Communications
• Carrier Aggregation for LTE
• Enhanced Downlink Multiple Antenna Transmission for LTE
• Uplink Multiple Antenna Transmission for LTE
• Relays for LTE
• Enhanced Inter-Cell Interference Control (ICIC) for non-
Carrier Aggregation (CA) based deployments of
heterogeneous networks for LTE
• LTE Self Optimizing Networks (SON) enhancements
• Further enhancements to MBMS for LTE
• Minimization of Drive Tests for E-UTRAN and UTRAN
• HNB and HeNB Mobility Enhancements

Release 11
• Network-Based Positioning Support in LTE
• Study on System Enhancements for Energy Efficiency
• Study on Coordinated Multi-Point operation for LTE

LTE-Advanced Technologies

LTE-Advanced
The advanced toolbox for making more out of LTE
GSM
LTE
CDMA/EVDO
HSPA+
LTE
LTE
HSPA+
LTE
Subscribers reached
Band-
width
HSPA+
GSM
LTE
TD-LTE
More
users
More
intensive
usage
At more
locations
Intial LTE rollout
• LTE on initial bands
• Macro topology
Straight-forward evolution
• Additional bands (paired, unpaired)
• Refarming
Advanced evolution
• Macro + small cell topology
• Aggregated bands
• Advanced antenna
schemes
LTE-Advanced
+
More
bandwidth
Higher
data rates
Enhanced
coverage
Enhance
macro
network
performance
Enable
efficient use
of small cells

The LTE-Advanced toolbox for delivering more
data efficiently to wide areas and hotspots
Enable efficient use of small cells
Enhance macro network performance
Relaying
Heterogeneous
Networks
100 MHz
Carrier Aggregation
Carrier1 Carrier2 Carrier3 … Carrier5
up to 100 MHz
MIMO
8x 4x
Coordinated Multipoint
Peak data rate and
throughput scaling
with aggregated
bandwidth
Peak data rate scaling with
antenna paths for urban grid
and small cells
MIMO
Capacity and cell edge performance
enhancements by active
interference cancelation
Enables focused
capacity enancement
with small cells by
interference
coordination
Enables focused
coverage extensions
with small cells by self-
backhaul

HetNet
• Consist of deployments where low power nodes are placed throughout a macro-
cell layout
• The interference characteristics in a heterogeneous deployment can be
significantly different than in a homogeneous deployment
• Mainly, two different heterogeneous scenarios are under consideration
– Macro-Femto (CSG: Closed Subscriber Group) case
– Macro-Pico case

TDM eICIC Principle
- combined macro+pico+HeNB case
Almost blank, or
MBSFN sub-frame
Sub-frame with
normal transmission
Macro-layer
Pico-layer
HeNB-layer
Macro-eNBs and Pico-eNBs can schedule also users
that are close to non-allowed CSG HeNB(s), but not
pico-UEs with larger RE.
Pico-nodes can schedule UEs with
larger RE, if not interfered from non-
allowed CSG HeNB(s)
Pico-UEs
with larger
RE, close to
CSG
HeNB(s)
are
schedulable

Coordination between two cell layers

Relay
• Relay
– as a tool to improve e.g. the coverage of high data rates, group mobility,
temporary network deployment, the cell-edge throughput and/or to provide
coverage in new areas
• Rel-10 relay deployment scenario
– Stationary relay
– Single hop relay
– No Inter relay handover

Relay Types
• Type 1 Relay
– It control cells, each of which appears to a UE as a separate cell distinct from donor cell
 Has unique physical-layer cell identity (defined in Rel.8)
 Shall transmit its own synchronization, reference symbols, ..
– The same RRM mechanisms as normal eNB
– No difference in accessing cells controlled by a relay and cells controlled by a “normal”
eNB from a UE perspective
– Shall appear as a Rel.8 eNB to Rel.8 UE
• Type 2 Relay
– It does not have a separate Physical Cell ID
– It is transparent to Rel-8 UEs;
 A Rel-8 UE should not be aware of the presence of a type 2 relay node
– At least part of the RRM is controlled by the eNB to which the donor cell belongs
– It can transmit PDSCH
– At least, it does not transmit CRS and PDCCH
– L2 relay, smart repeaters, decode-and-forward relays
– Not included in Rel.10

Type 1 vs. Type 2
Coverage extension perspective Throughput enhancement perspective

 CoMP transmission schemes in downlink
• Joint processing (JP)
 Joint transmission (JT): Downlink physical shared channel (PDSCH) is transmitted
from multiple cells with precoding using DM-RS among coordinated cells
 Dynamic cell selection: PDSCH is transmitted from one cell, which is dynamically
selected
• Coordinated scheduling/beamforming (CS/CB)
PDSCH is transmitted only from one cell site, and scheduling/beamforming is coordinated among cells
 CSI feedback (FB)
• Explicit CSI FB (direct channel FB) is investigated to conduct precise precoding, as well as implicit CSI FB (precoding
matrix index FB) based on Rel. 8 LTE
 Tradeoff between gain and FB signaling overhead
Coherent combining or
dynamic cell selection
Coordinated scheduling/beamformingJoint transmission/dynamic cell selection
CoMP Transmission in Downlink

CoMP Operations – JP, CS/CB

 CoMP reception scheme in uplink
• Physical uplink shared channel (PUSCH) is received at multiple cells
• Scheduling is coordinated among the cells
 Improve especially cell-edge user throughput
• Note that CoMP reception in uplink is implementation matter and does
not require any change to radio interface
Receiver signal processing
at central eNB (e.g., MRC, MMSEC)
Multipoint reception
CoMP Reception in Uplink

Multi-cell Joint Operations
• Normal cellular unicast communications
• Inter-cell interference!
• Soft handover
• Reduced inter-cell interference but with SE
loss
• MBSFN
• No inter-cell interference w/o SE loss,
but only for multicast communcations
• COMP – JP
• Reduced inter-cell interference w/o SE loss,
but requires significant X2 bandwidth
a b
b
a a
b
a a
a
a b

DL MIMO Trend

?
• In CL-SU-MIMO, SVD-MIMO is the optimum
SVD MIMO as a closed-loop MIMO

x~
x
V VH U UH
y
minn
1 1
~w
min
~
nw

Pre-processing Post-processing
Channel
),0(~,, 0 r
rt
n
nn
NΝCC Iwyx
wHxy


y~
With number of transmitting antenna=nt and receiving antenna=nr,
MIMO Channel Decomposition

wUxD
wxVUDVU
wxUDVU
wHxU
yUy
H
HH
HH
H
H





~
)~(
)(
)(
~
wxDy ~~~ 
Channel Diagonalization

• Benefits of Spatial Diversity
– Array gain
– Diversity gain and decreased error rate
– Increased data rate
– Increased coverage or reduced transmit power
• Receive Diversity
– Selection combining, Equal gain combining, and Maximal radio combining (MRC)
• Transmit Diversity
– Open-loop transmit diversity: e.g., Alamouti coding
– Closed-loop transmit diversity: e.g., Linear precoding
y = G(HFx + n)
where x is the transmited symbol vector, y is the received symbol vector with M x 1,
G is the post-coder matrix with M x Nr, H is the channel matrix with Nr x Nt, F is the
precoder matrix with Nt x M
For the diversity precoding, M = 1, and the SNR maximizing precoder F and
postcoder G are the right- and left- singular vectors of H corresponding to its
singular value, max.
Spatial Diversity

• DOA (Direction-Of-Arrival)-based Beamforming
– Physically directed
– Incoming signals to a receiver may consist of desired energy and interference energy.
– From the acquired DOAs, a beamformer extracts a weighting vector for the antenna
elements and uses it to transmit or receive the desired signal of a specific user while
suppressing the undesired interference signals.
– Often called null-steering beamformer
– Viable only in LOS environments or in environments with limited local scattering
around the transmitter
• Eigen Beamforming
– Mathematically directed
– Eigen beamforming exploits CSI of each antenna element to find array weights that
satisfy a desired criterion, such as SNR maximization or MSE minimization.
– Eigen beamforming is conceptually nearly identical to the linear diversity precoding,
the only difference being that the eigen beamforming takes interfering signals into
account.
– More viable in realistic wireless broadband environments, which are expected to have
significant local scattering
Beamforming

3GPP Release 8 LTE DL transmission modes
Two approaches to multi-antenna transmission
MCS
CQI
PMI
Rank CQI
MCS
PMI
Rank
PDSCH Channel estimation based
on common reference signal (CRS)
MIMO Beamforming
PDSCH Channel estimation based on
dedicated reference signal (DRS)
CRS
DRS
SRS
Closed loop, codebook precoding (#4) Open loop, non-codebook precoding (#7)

3GPP Release 9 LTE DL transmission modes
Enhanced beamforming: dual-layer beamforming (#8)
With cross polar antennas in mind CMCC have
been eager to extend Rel8 Beamforming to
support two streams.
Spatial multiplexing supported
- Up to 2 layers per user (SU-MIMO)
- Up to 4 layer in total (MU-MIMO)
CRS based PMI and rank reporting supported
for beamforming
- Similar feedback schemes as for Rel-8 SU-
MIMO
(tx-mode 4)
- TxD CQI also supported
- One CRS per polarization via sector beam
virtualization (as in Rel-9)
CQI
PMI
Rank
MCS
Rank
PDSCH Channel estimation
based on DRS
DRS
SRS

• Diversity
– Same data on all the pipes
 Increased coverage and link quality
– But, the all pipes can be combined to make a kind-of beamforming
• MIMO
– Different data streams on different pipes (mode 4)
 Increased spectral efficiency (increased overall throughput)
 Power is split among the data streams
• Beamforming
– Data stream on only the strongest pipe (mode 7)
 Use all the power on the strongest pipe (i.e., the most efficient pipe)
 Increased coverage and signal SNR
– Not any more focusing on the strongest pipe in transmission mode 8 in R9
Multi-Antenna Technology Summary

 Extension up to 8-stream transmission
• Rel. 8 LTE supports up to 4-stream transmission, LTE-Advanced supports up to 8-stream
transmission
 Satisfy the requirement for peak spectrum efficiency, i.e., 30 bps/Hz
 Specify additional reference signals (RS)
• Two RSs are specified in addition to Rel. 8 common RS (CRS)
- Channel state information RS (CSI-RS)
- UE-specific demodulation RS (DM-RS)
 UE-specific DM-RS, which is precoded, makes it possible to apply non-codebook-based
precoding
 UE-specific DM-RS will enable application of enhanced multi-user beamforming such as
zero forcing (ZF) for, e.g., 4-by-2 MIMO
Max. 8 streams
Enhanced
MU-MIMO
Higher-order MIMO
up to 8 streams
CSI feedback
Enhanced Multi-antenna Techniques in DL

 Introduction of single user (SU)-MIMO up to 4-stream transmission
• Whereas Rel. 8 LTE does not support SU-MIMO, LTE-Advanced supports up to 4-stream
transmission
 Satisfy the requirement for peak spectrum efficiency, i.e., 15 bps/Hz
 Signal detection scheme with affinity to DFT-Spread OFDM for SU-MIMO
• Turbo serial interference canceller (SIC) is assumed to be used for eNB receivers to
achieve higher throughput performance for DFT-Spread OFDM
 Improve user throughput, while maintaining single-carrier based signal transmission
Max. 4 streams
SU-MIMO up to 4 streams
Enhanced Multi-antenna Techniques in UL

Carrier aggregation
More dynamic spectrum usage for better user experience
1 Gbps and beyond
• Will be specified in 3GPP
Rel.11 or later
• Most operators have
significantly less spectrum
for LTE
• Even HD streaming services
demand less than 20Mbps
Resource allocation gain
• Ultrafast resource allocation
by scheduler instead of
handover
• Users dynamically get the
best resources of
aggregated carrier
• Higher average data rates
Peak data rate addition
• enables competitive peak
data rates on non-
contiguous spectrum
• Mitigates the challenge of
fragmented spectrum
Example:
spectrum assets peak data rate
on Cat.4 device
With CA150 Mbps
75 Mbps
225
Mbps
20MHz in 2.6GHz band
10MHz in 800MHz band
Relevant scenarios in near future (3GPP Rel.10)
20MHz 300Mbps
20MHz 300Mbps
20MHz 300Mbps 1.5Gbps
20MHz 300Mbps
20MHz 300Mbps

 Wider bandwidth transmission using carrier aggregation
• Entire system bandwidth up to, e.g., 100 MHz, comprises multiple basic frequency blocks
called component carriers (CCs)
 Satisfy requirements for peak data rate
• Each CC is backward compatible with Rel. 8 LTE
 Maintain backward compatibility with Rel. 8 LTE
• Carrier aggregation supports both contiguous and non-contiguous spectrums, and
asymmetric bandwidth for FDD
 Achieve flexible spectrum usage
Frequency
System bandwidth,
e.g., 100 MHz
CC, e.g., 20 MHz
UE capabilities
• 100-MHz case
• 40-MHz case
• 20-MHz case
(Rel. 8 LTE)
Carrier Aggregation

Carrier and Spectrum Aggregation
Two types of aggregation
• Contiguous carrier aggregation in a same frequency band
– Maybe difficult to find out frequency bands where maximum of 200MHz (FDD)
can be allocated in contiguous manner
• Non-contiguous carrier aggregation in different frequency band
– Possibility for wider total bandwidth without correspondingly wider contiguous
spectrum
– Feasibility, complexity and cost analysis should be done in RAN4 WG

SON

• 기지국 수의 증가  설치 및 운용 비용 증가
• Performance optimization  빈번한 re-configuration 필요
Why SON?

How many parameters it
takes to have one base
station configured?
500

How many parameters it
takes to run a 3G
network?
Over
64,000,000

Nokia Siemens Networks’ SON Suite is built on our
detailed understanding of how networks operate
Nokia Siemens Networks SON Suite
LTE SON
2G/3G SON
Open
northbound interfaces
SON
Other vendor
network
Mobile
Core
Self
configuration Automated Neighbor Relations
Plug and Play
Self
optimization
Interference optimization
Load balancing
Power saving
Mobility robustness
Minimization of Drive Tests
Self
healing
Cell outage detection &
compensation
Self healing / alarm
management

PCI management
23
14
1
66
412
500
234
322
98
• “collision-free”: the Phy_ID is unique in the
area that the cell covers, no two cells
overlap with identical Physical Cell IDs
 neighbors need to be known
• “confusion-free”: a cell shall not have
neighboring cells with identical Phy_ID
 neighbors of the neighbors
Automatic assignment of PCI parameter values
ID A ID A
ID A ID AID B

PRACH management
Automatic assignment of PRACH settings
• Auto-configuration of parameter settings for
• PRACH cyclic shift
• PRACH configuration index
• PRACH frequency offset
• PRACH Root sequence
• Considers dependencies and consistencies
• Based on network configuration data / UE behavior / cell load
/ operator policy

eNB-B
IP@B
3GPP UE Based ANR
2. RRC measurement
report (Phy_ID=3)
1. Measure the signal ( Phy_ID=3)
4. Read GID (“B10”) from BCCH
3. Report request
to report GID for Phy_ID=3
5. Report
GID=“B10”
eNB-A
IP@A
0. UE Measurement Configuration
when UE enters RRC_CONNECTED
Goal: retrieve Global Cell ID from new discovered neighbor cell
Phy-ID: physical cell ID
GID: Cell Global ID

Minimization of drive tests (MDT)
Detailed trace data collection allows detailed analysis
MMES-GWNetAct
Normal trace data
+ Periodic UE measurements
+ Timing Advance
+ UE RLF Report
+ UE logged data
Trace Data collected also includes
• Timing Advance information
• Measurement information provided
by periodic UE-measurements
• UE Radio Link Failure Report
(works only with Rel. 9 UEs)
Usable for e.g.
• Interference matrix (interference
map)
• Location analysis on radio link
failures (RLF)  input for cell and
coverage optimization

SON - Mobility Robustness (MRO)
Increased network performance by automatic adaptations
• Optimizing the Intra-LTE (Intra-frequency) radio network HO-configuration
for robustness of mobility procedures
• MRO fine tunes based on long-running evaluation of KPIs / specific detections
in eNBs / influenced by operator policies
• Prevents too early HO, too late HO, and HO to wrong cell
NetAct
PM-history
Height Measuremant dataMeasurement data
MRO
-SF
MRO
-SF
Optimizer/Configurator
CMPM PM
Performance Measurements
CM

MRO Enhancement in Release 10
The use case is to enable detection and to provide tools for possible
correction of following problems:
• Connection failures in inter-RAT environment:
o Priority 1: at HOs from LTE to UMTS/GSM
o Priority 2: at HOs from UMTS/GSM to LTE
• Obtaining UE measurements in case of unsuccessful re-establishment
after connection failure
• Ping-pongs in idle mode (inter-RAT and intra-LTE environment)
• Ping-pongs in active mode (inter-RAT)
• HO to wrong cell (in intra-LTE environment) that does not cause
connection failure (e.g. short stay problem)

Cell outage compensation (COC)
Compensate the gap in network coverage
- due non availability of cells / eNBs
• Calculate modified radio network configuration for neighbor eNBs
• Based on radio planning, data is available in NetAct
• RET (Remote Electronic Tilt) changes
Flexi Multiradio BTS
SON entity
Cell/sector outage compensationCell/sector outage

Summary

LTE-Advanced Improvements

Long Term HSPA Evolution

Long Term HSPA Evolution (beyond 3GPP Rel-10):
Designed to offer 672 Mbps
Present Future
3GPP
Release
11+
Long Term
HSPA
Evolution
New features
Carrier Aggregation
Multipoint Systems
8 x 5 MHz
HSPA+LTE
aggregation
HSPA +
LTE
MIMO
MIMO 2x4x
HSPA/HSPA+
Long Term
HSPA
Evolution
using similar
technology as
LTE-
Advanced:
• Carrier
aggregation
• MIMO
• Multipoint
Systems

Thank you !
www.nokiasiemensnetworks.com
Nokia Siemens Networks
20F, Meritz Tower, 825-2
Yeoksam-Dong, Kangnam-Gu
Seoul 135-080, Korea
Bong Youl (Brian) Cho
RAN Solutions Manager, Ph. D.
brian.cho@nsn.com
Mobile 010-4309-4129

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