lte advanced

LTE-Advanced

October 2011

Bong Youl (Brian) Cho, 조 봉 열

[email protected]

mailto:[email protected]

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-Advanced Release 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)



Syste

m

Perf

orm

an

ce

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/beamforming Joint 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

nnNΝCC 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 CA 150 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 A ID 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

MME S-GW NetAct

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 data Measurement data

MRO -SF

MRO -SF

Optimizer/Configurator

CM PM 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 compensation Cell/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 2x 4x

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.

[email protected]

Mobile 010-4309-4129

mailto:[email protected]

Engineering

lte advanced