lte enhancement

NTT DOCOMO, INC., Copyright 2012, All rights reserved. 1

Further LTE Enhancements toward Future Radio Access

Takehiro Nakamura NTT DOCOMO, Inc.


LTE Release 10/11 (LTE-Advanced) Standardization


3GPP仕様のリリース 1999 2000 2001 2002 2003 2004 2005

Release 99

Release 4

Release 5

Release 6

1.28Mcps TDD

HSDPA

W-CDMA

HSUPA, MBMS

2006 2007 2008 2009

Release 7 HSPA+ (MIMO, HOM etc.)

Release 8

2010 2011

LTE

Release 9

Release 10

GSM/GPRS/EDGE enhancements

Minor LTE enhancements

2012 2013

Release 11

ITU-R M.1457 IMT-2000 Recommendation

LTE-Advanced ITU-R M.2012 IMT-Advanced

Recommendation

Approved at ITU-R RA in Jan. 2012

3GPP TSG-RAN Workshop on Release 12 onward to be held on June 11-12, 2012


Key Requirements for LTE-Advanced

March 4, 2011

• LTE-Advanced shall be deployed as an evolution of LTE Release 8 and on new

bands. • LTE-Advanced shall be backwards

compatible with LTE Release 8 Smooth and flexible system migration

from Rel-8 LTE to LTE-Advanced

LTE Rel-8 cell

LTE Rel-8 terminal LTE-Advanced terminal

LTE-Advanced cell

LTE Rel-8 terminal LTE-Advanced terminal

LTE-Advanced backward compatibility with LTE Rel-8

An LTE-Advanced terminal can work in an LTE Rel-8 cell

An LTE Rel-8 terminal can work in an LTE-Advanced cell

LTE-Advanced (LTE Release 10)

LTE Release 8

LTE-Advanced contains all features of LTE Rel-8&9 and additional features for further evolution

LTE Release 9

LTE-Advanced evolved from LTE Rel-8


Key Features in LTE Release 10&11 Support of Wider Bandwidth(Carrier Aggregation) Rel-10&11

• Use of multiple component carriers(CC) to extend bandwidth up to 100 MHz • Common physical layer parameters between component carrier and LTE Rel-8 carrier Improvement of peak data rate, backward compatibility with LTE Rel-8

Advanced MIMO techniques Rel-10 • Extension to up to 8-layer transmission in downlink • Introduction of single-user MIMO up to 4-layer transmission in uplink • Enhancements of multi-user MIMO Improvement of peak data rate and capacity

Heterogeneous network and eICIC(enhanced Inter-Cell Interference Coordination) Rel-10&11

• Interference coordination for overlaid deployment of cells with different Tx power Improvement of cell-edge throughput and coverage

Relay Rel-10 • Type 1 relay supports radio backhaul and creates a separate cell and appear as Rel-8

LTE eNB to Rel-8 LTE UEs Improvement of coverage and flexibility of service area extension

Coordinated Multi-Point transmission and reception (CoMP) Rel-11 • Support of multi-cell transmission and reception Improvement of cell-edge throughput and coverage

Interference rejection combining (IRC) UE receiver Rel-11 • Improved minimum performance requirements for E-UTRA Improvement of cell-edge throughput

100 MHz

f CC


Future Radio Access (LTE Release 12 and Beyond)


Growth of Packet Traffic in DOCOMO • Various services, especially video services, and high-speed mobile access

increased amount of mobile data traffic – Approx. 1.6 times per year (2004 – 2009) – Approx. 2 times per year (2010-2011)

• Further traffic growth is projected due to dramatic increase in Smartphone sales


By 2015, the mobile data traffic footprint of a single subscriber could be 450 times what it was 10 years earlier in 2005.

Forecast of Mobile Data Traffic Growth

Mobile video has the highest growth rate of any application category

Cisco VNI Mobile:

Consensus in the industry is that there will be substantial growth in demand for mobile data traffic over the next 5 – 10 years

UMTS Forum:


Approach for Capacity Enhancements

Spectrum extension

Network density

Required capacity (bps/km2 = bps/Hz/cell x Hz x cell/km2)

Spectrum efficiency

Current capacity

New cellular concept for cost/energy-efficient dense deployments

Non-orthogonal multiple access

Study for new interference scenarios

Dense urban Shopping mall

Home/office

Cellular network assists local area radio access

Hybrid access using coverage and capacity spectrum bands

Multiple access technologies with Tx-Rx cooperative

interference cancellation

Traffic offloading (alternative means for communication)

WiFi offload, D2D, etc.

We need set of radio access technologies to satisfy future requirements of 500-1000x capacity

Existing cellular bands Higher/wider frequency bands

Frequency

Very wide Super wide

Controller

TRx

TRx

TRx

TRx

TRx

TRx

TRx

TRx

Massive MIMO, Advanced receiver


Other Requirements (1)

Mob

ility

Data rate

1 Gbps wide area

10 Gbps peak IMT-Advanced

van diagram Mob

ility

Data rate

100 Mbps wide area

1 Gbps peak IMT-Advanced

van diagram

10x improvement in the next decade More spectra utilized efficiently

Requirements mainly from user perspective

Source: Artist4G (FP7 ICT), Jan. 2010

• Higher data rate and user-experienced throughput

– Data rate competitive to that of future wired networks

• Gbps-order experienced throughput

– Low latency for improving user experience

• Fairness of user throughput

– In a cell • Improve cell-edge throughput

– Among cells • Urban to rural • Digital divide

– Among users • Lower system impact from few

heavy users

Gbps-order experienced throughput


Other Requirements (2)

• Flexible, easy, and cost-efficient operation

– For diverse spectrum allocation • Efficient utilization of

higher/wider frequency bands – For diverse environments and

network nodes/devices with different types of backhauling

• RRE, Femto, relay, etc. – For diverse types of services, user

devices, and communication methodologies

• MTC, thin client, etc. • Energy saving (Green)

– Reduction in joule per bit • System robustness against

emergencies – Earthquake, Tsunami, etc.

Requirements mainly from operator perspective

Different duplex schemes may be applied

Frequency

Non-contiguous spectrum allocation over wide range of frequencies

Macrocells RRE Femto

Robustness to emergencies


Possible Standardization Scenario • Standardization scenario towards 2020

– Mid-to-long term evolution introducing new technologies to achieve required capacity gain based on 3GPP LTE radio interface

– The following two types of evolutions to be considered

• Backward-compatible evolutions – Evolutions backward compatible to legacy UEs sharing the same spectrum bands – New technologies to be introduced, e.g., for further improving spectrum efficiency

• Most of new radio access technologies can be introduced in future LTE releases using LTE (OFDM/SC-FDMA) based signal waveform

• Complementary evolutions – Introduction of new carrier type that is complementary to legacy carrier type(s) with

backward-compatible evolutions – Evolutions focusing on new frequency spectrum bands and/or specific scenarios

such as enhanced local area radio access

Rel. 8 Rel. 10

Rel. 1X

Rel. 11 Rel. 1X

Legacy carrier type Rel. 11 Rel. 1X

Additional carrier type

New carrier type or new radio inter face

Complementary evolutions

Backward-compatible evolutions

New RAT?


Technologies Related to Efficient Spectrum Extension and Utilization

Spectrum extension

Capacity


Wider Bandwidth • Super-wideband to achieve “Gbps” as typical data rate

At least more than 200 MHz will be desirable (maybe up to 1 GHz)

• Utilization of much higher frequencies – Maybe possible to find contiguous wideband spectrum in higher frequency

Bandwidth Spectrum efficiency 100 MHz 10 bps/Hz (4x4 MIMO) 200 MHz 5 bps/Hz (2x2 MIMO) 300 MHz 3.3 bps/Hz (~64QAM) 600 MHz 1.7 bps/Hz (~16QAM) 1000 MHz 1 bps/Hz (~QPSK)

Examples to achieve 1-Gbps data rate

FRA Gbps to be achieved with lower spectrum efficiency, e.g., without MIMO (More than 10-Gbps can be achieved by MIMO technology)

LTE-A

Existing cellular bands Higher frequency bands

Frequency

Very wide (e.g. > 3.5GHz)

Super wide (e.g. > 10GHz)

How to use in cellular systems ?


Efficient Spectrum Utilization • Hybrid radio access using lower & higher frequency bands

– Basic coverage/mobility supported in lower frequency bands, e.g., existing cellular bands

• Current Service Quality in terms of Connectivity/ Mobility can be maintained • Support control signaling for efficient small-cell discovery

– High speed data transmission supported in higher frequency bands • Large bandwidth • Mainly for smaller or denser cell deployments

Existing cellular bands (high power density for coverage)

Higher frequency bands (wider bandwidth for high data rate)

Frequency

Very wide (e.g. > 3.5GHz)

Super wide (e.g. > 10GHz)

Hybrid radio access

Macro-cellular deployments supporting full coverage area

Various local area scenarios with low-power nodes/devices


Technologies for Efficient Support of Denser Network Deployments

Capacity


Requirements for Denser Network Deployments

• Capacity per NW cost (bps/cost) = Capacity per unit area / NW cost per unit area

• Efficient small cell identification & mobility – UE battery saving

• Can be optimized to low mobility – Support for non-uniform deployments

• Dense cells for high traffic area • Less efforts on cell planning

(bps/km2 (= bps/cell x cell/km2))

km

km

(cost/km2) Spectrum efficiency x bandwidth

- Low cost NW node & backhaul deployments

- Easy cell planning & maintenance - NW energy saving

Macro cell

Small cell


Deployment Scenarios • Two deployment scenarios are identified for small-cell

deployments (increasing network density): – Scenario 1 (Mixed deployment scenario):

• Small cell and Macro cell co-exist on a single carrier.

– Scenario 2 (Small-cell dedicated carrier scenario): • Small cell utilizes a dedicated carrier, where no Macro cell exists.

F1

F2

F0

Scenario 1: Mixed deployment scenario Scenario 2: Small-cell dedicated carrier scenario

Secenario 1 was studied in Rel-11. We assume Scenario 2 getting more and more important in Rel-12 onward


RRH CA Deployments

2 GHz (Example)

3.5 GHz (Example)

Macro cell

Macro cell link can maintain good connectivity and mobility

RRH link can provide high throughput due to frequency reuse using small RRH cells

Additional carrier type for RRH link would provide more flexible and cost/energy-efficient operations

RRH

RRH

RRH

RRH

RRH link

Macro cell link


Technologies for Further Enhancing Spectrum Efficiency

Spe

ctru

m

effic

ienc

y

Capacity


Different Requirements Between WA and LA Spectra

• Different requirements for radio access between Wide Area (WA) and Local Area (LA) spectra in HetNet deployments – But, commonality between WA and LA to be considered within a

framework of LTE-based radio interface

Macro-cellular deployments supporting full coverage area

Various local area scenarios with low-power nodes/devices

Wide Area spectrum Local Area spectrum Spectrum efficiency Very important

(limited BW) Important (may not be critical if large BW available)

Mobility Medium-to-High Low Coverage Essential Not critical

(but wider is better) DL/UL radio link Asymmetric More symmetric Traffic load More uniform

(many users & cell planning) More fluctuated (less users & non-uniform deployments)


FDD/TDD in Local Area • FDD is advantageous over TDD in wide area

– No need for synchronization among cells/operators • The adjacent channel interference is much lower than in TDD

– Wider coverage and lower latency owing to continuous transmission • DL/UL channels are always "open“

• TDD might be more applicable in local area & in higher frequency bands – Requirements on synchronization among operators can be relaxed in local area – Potential benefits in spectrum sharing between DL/UL – Dynamic TDD

• Traffic is more bursty (unbalanced DL/UL) in local area • Interference management of DL/UL transmissions is required among multi-points

– Possibly facilitate worldwide harmonized spectrum allocation • Flexible spectrum allocation • No need for guard band (No need for duplexer)

UL DL

UL DL

UL DL

UL DL

DL UL

DL DL

User #2 User #1

User #3 User #4

User #2 User #1

User #3 User #4 Enhanced

efficiency

Static DL/UL allocation

Dynamic DL/UL allocation


Concept of Hybrid Radio Access • Hybrid radio access

– Adaptation of radio access schemes according to environments, spectrum bands, types of traffic, etc.

• Required high commonality in radio interface among radio access schemes

• Example of hybrid access schemes – Hybrid FDD and TDD according to cell environments – Hybrid non-orthogonal and orthogonal multiple access schemes

according to, e.g., path loss variation among users

– Hybrid multi-carrier and single-carrier transmission schemes according to, e.g., required coverage or cell environments

Wide area/lower frequency Local area/higher frequency

Adaptation for radio access schemes

Resource mapping & Power control

DFT (SC)

S/P (MC) Tx data IFFT Transmission

Local area

Wide area

freq/time Orthogonal

freq/time Non-orthogonal

Path loss variation Large Small (Wide area) (Local area)


Conclusion • LTE Release 10 and 11

– LTE Release 10 was developped and approved in ITU-R M.2012 as LTE-Advanced

– LTE Release 11 is under development to enhance LTE Release 10 technologies

• Future Radio Access (LTE Release 12 and beyond) – 3GPP will hold a Workshop on Release 12 onward to identify

requirements and potential technologies for Future Radio Access – Variety of requirements including reduced cost and further capacity

enhancements needed by traffic explosion – Two evolution scenarios, backward compatible evolution and

complementary evolution, to satisfy both of backward compatibility and sufficient gain

– Key techniques to meet requirements • Efficient utilization of higher and wider spectrum bands • New small-cell dedicated carrier for efficient and simple NW densification • Hybrid Radio Access for wide area and local area enhancements

lte enhancement

Technology