18 lte-advanced overview - tor leif aarland

8/4/2019 18 LTE-Advanced Overview - Tor Leif Aarland

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Customer Confidential

1 © Nokia Siemens Networks Presentation / Author / Date

LTE-AdvancedTor Leif Aarland

Kursdagene 2010





LTE: Current Status

• 3GPP has finalized the LTE specifications for Release 8 Backwards compatibility maintained: March 2009 for radio / June 2009 for RAN interfaces

• Release 9 is maturing and completion is expected in December 2009 (functionalfreeze) / March 2010 (ASN.1)

• LTE key features: OFDMA in downlink and DFT-S-OFDMA (aka SC-FDMA) in uplink.

Bandwidths ranging from 1.4 MHz up to 20 MHz. Both TDD and FDD modes are supported. Optimized for macro cells, works even with very high mobility. Channel-aware scheduling in both time and frequency domain Uplink power control for reduction of inter-cell interference. Fast CQI based link adaptation, Turbo coding utilized together with Hybrid ARQ retransmissions. Up to 4x4 single-user MIMO support in downlink (no SU-MIMO support in uplink):

• Open-loop spatial multiplexing, closed-loop precoded spatial multiplexing, rank-1 beamforming and transmit

diversity supported. Multi-user MIMO supported both in uplink and downlink.

• With these features, LTE Rel.8 supports peak data rates exceeding 300 Mbit/sin DL and 75Mbit/s in UL, and a cell average spectral efficiency gain of x 2-3over HSPA Rel.6





LTE-Advanced: Background

• ITU-R has issued a Circular Letter early 2008 to invite

candidate Radio Interface Technologies for IMT-Advanced.

• In the circular letter, key features of IMT-Advanced are listed.From physical layer perspective, one important requirement isstated as: “ enhanced peak data rates to support advanced

services and applications (100 Mbit/s for high and 1 Gbit/s for low mobility were established as targets for research)”

• To enhance LTE features further to fulfill all IMT-Advancedrequirements and hence become an IMT-Advanced technology,3GPP has started a new Study Item on LTE-Advanced inMarch 2008.

• Currently, 3GPP RAN is studying and evaluating theperformance of the new relevant technology components.





Work Item

3GPP LTE-A vs. ITU-R Schedule

2009 2010 20112007 2008

3GPP RAN

ITU-R WP5D

#38 #39 #40 #41 #42 #43 #44 #45 #46 #47 #48

#49

#1 #2 #3 #4 #5 #6 #7 #8 #9

WS 2nd WS

#10

Work ItemStudy Item

#11 #12

3GPP early ITU-R

submission

approved.

Submit a complete technology

proposal to ITU-R.

Study Item technical report

approved in 3GPP. Submit

final proposal to ITU-R,

including performance

evaluation.

“Early proposal”

submission.

“Complete

technology”

submission.

“Final”

submission.

Detailed schedule >>Submissions done,

Work items not started.





LTE-Advanced: General Requirements

• 3GPP has set its own requirements for LTE-Advanced

• The main high-level requirements

– To meet/exceed IMT-Advanced capabilities

– 3GPP operator requirements for the evolution of E-UTRA

• Backwards compatibility requirements

– A Release 8 E-UTRA terminal can work in an Advanced E-UTRAN

– An advanced E-UTRA terminal can work in an Release 8 E-UTRAN

– Non-backward compatible elements could be considered based on TSGRAN decision

See TR 36.913

for all

requirements!





LTE-Advanced: Key Ingredients

Bandwidth Extension

MIMO

Cooperative Systems

Relaying

8x 4x

100 MHz

Smooth

Migrationto LTE-A

Backwardcompatible

to LTE

Mobility

1st LTEfield trialBerlin, 11/2007

+Heterogeneous Networks

in June 2009





Potential of LTE-Advanced Components= clear gain

= moderate gain

LTE-Advanced provides a toolbox of solutions improving radio

performance

Carrieraggregation1

MIMOenhancements2

Peak rate

CoMP3

Average rate(capacity)

Cell edge rate(interference)

Coverage(noise limited)

++ + ++ +

++(o)

++(+)

++(+)

o

o + ++ ++

Heterogeneous

networks4 o ++ ++

Relays5 o o + ++

1Multiple component carriers on the same or different spectrum2Including more transmit and receive antennas in downlink and in uplink,() without increasing the number of antennas3Coordinated multipoint transmission4Optimized usage of local and wide area cells5Decoding and encoding relay – similar to self backhauled base station

+





Technology Evolution Enables LTE-Advanced

Opticaltransport

availability

Multiplepower

amplifiersin UE

4-8

antennas inUE

More

spectrumMultibandUE andBTS

capabilityCarrier aggregation

MIMOenhancements

CoMP

Heterogeneousnetworks

Relays

Multi-antennaBTS site

Basebandprocessingcapability

Low costsmall BTS

LTE-Advanced benefits from technology evolution inbaseband and RF area, the new available spectrumand the optical fiber availability

LTE-A

http://images.google.fi/imgres?imgurl=http://fiberopticindustry.com/images/fiber_optics/fiber_optics_250x251.jpg&imgrefurl=http://fiberopticindustry.com/result.php%3FKeywords%3DFiber%2520Optic%2520Cable&usg=__PDSZg9BhnzUoWQR8XOjNb1mmEY8=&h=251&w=250&sz=9&hl=fi&start=14&um=1&tbnid=2CMjITHmnlhVvM:&tbnh=111&tbnw=111&prev=/images%3Fq%3Dfiber%2Boptics%26hl%3Dfi%26rlz%3D1T4SUNA_enFI268FI319%26um%3D1

http://images.google.fi/imgres?imgurl=http://comps.fotosearch.com/comp/UNC/UNC265/antenna-icons-cell_~u30842309.jpg&imgrefurl=http://www.fotosearch.com/UNC265/u30842309/&usg=__hnqzjj9qIiVHVRDWaEP-hYIEEJc=&h=320&w=300&sz=22&hl=fi&start=13&um=1&tbnid=rf9CdnRQGsiAEM:&tbnh=118&tbnw=111&prev=/images%3Fq%3Dmobile%2Bphone%2Bantennas%26hl%3Dfi%26rlz%3D1T4SUNA_enFI268FI319%26um%3D1

http://images.google.fi/imgres?imgurl=http://blogs.sun.com/staso/resource/spectrum3.jpg&imgrefurl=http://blogs.sun.com/staso/entry/face_the_spectrum&usg=__pHqBGSqurSwyzFtvOKOU2CeyB8k=&h=334&w=485&sz=13&hl=fi&start=2&um=1&tbnid=MRy0izUjbafcEM:&tbnh=89&tbnw=129&prev=/images%3Fq%3Dspectrum%26hl%3Dfi%26rlz%3D1T4SUNA_enFI268FI319%26um%3D1





Bandwidth Extension

• High peak data rate of 1 Gbps in downlink and 500 Mbps in uplink can beachieved with bandwidth extension from 20 MHz up to 100 MHz.

• Backwards compatibility requirements with Release 8 LTE is achieved withcarrier aggregation

• We combine N Release 8 component carriers, together to form N x LTEbandwidth, for example 5 x 20 MHz = 100 MHz etc.

• LTE terminals receive/transmit on one component carrier, whereas LTE-Advanced terminals may receive/transmit on multiple component carrierssimultaneously to reach the higher bandwidths.





Uplink MIMO

• Uplink single-user MIMO is being introduced in order to increase averageuser throughput and, in particular, user throughput at the cell edge

– UL SU-MIMO was considered already for Release 8 LTE, but compared to the addedbenefit, it was found too expensive for the terminals due to need of multiple poweramplifiers.

– Now, up to 4 TX antenna transmission will be specified for LTE-Advanced uplink.

• The same (type of) schemes will likely be supported as in downlink: – Closed-loop rank-1 phase beamforming and also precoded

spatial multiplexing (frequency selective / non-selective) – Open loop transmit diversity for conditions where instant channel state is not available – In spatial multiplexing the baseline option should have separately encoded layers to

facilitate efficient use of advanced receivers at the eNodeB – Rank adaptation for best matching to the channel conditions

• Key standardization issues for UL MIMO: – Design of precoding vectors and TX diversity

schemes with low PAPR for all channels(data/control)

– Design of reference signal structure allowing efficientlayer separation

– Efficient channel state / precoding informationfeedback versus signaling overhead, for closed-loopoperation.





Downlink MIMO

Downlink MIMO schemes are extended/enhanced from Release 8

LTE

Multi-user MIMO is enhanced by• Improved spatial interference suppression

at transmitter side; improved feedbackand precoding.

• Interference awareness at receiver side,enabling interference cancellation.

• Improved flexibility in frequency domainpacket scheduling.

Single-user MIMO operation is extended to support 8 TXantennas, (instead of 4TX supported by Release 8 LTE).• Eight layer operation not practical and no real need to support





CoMP Techniques

• CoMP = Coordinated Multiple Point transmission and reception

– Coordinated Transmission and reception for multiple cells

• Categories of CoMP:

– Joint Processing (JP): data is available at each cell in CoMP cooperating set

Joint Transmission: U-plane transmission from multiple points (part of or entire CoMP

cooperating set) at a time Dynamic cell selection: U-plane transmission from one point at a time (within CoMP

cooperating set)

• A single point is the transmission point at every subframe; this transmission point can changedynamically within the CoMP cooperating set

– Coordinated Scheduling/Beamforming (CS/CB): data is only available atserving cell (data transmission from that point)

The user scheduling/beamforming decisions are made with coordination among cellscorresponding to the CoMP cooperating set





Cell A

System level CoMP Joint ProcessingA simple example

Cell A (Anchor Cell for the CoMP Cooperative Set)

Cell BCell C

TX MU-MIMO Tx

TX MU-MIMO CoMP Rx

DL/UL Control channelsSU-MIMO CoMP Tx

SU-MIMO CoMP Rx

• A 3-cells CoMP Cooperative/Transmission Set serving 4 UE’s

– Thick DL arrows indicate data radio links; thin DL/UL arrows indicate control/signalingradio links to/from the UEs.

– The inter-cell CoMP signaling is assumed to be ideal!

• In the C-MIMO context the „MU-MIMO‟ term is used to indicate transmission withspatial multiplexing of several UEs on a given time-frequency physical resource

Inter-cell CoMP signaling

DL line style indicates Tx on the same TTI.DL line color indicates Tx on the same PRB.





Relays

Provisioning high data rates ubiquitously is challenging due to

• Higher attenuation at the envisaged new frequency rangesbetween 2 and 4 GHz

• Higher bandwidth for broadband means less power per Hertz

• Data users are often indoors, signals attenuated by walls

Relays can be used for improving the SINR conditions at celledge with low additional infrastructure cost.

• Relays are being considered for LTE-Advanced as a tool toimprove cell edge performance and fill coverage “holes”.

Relays are to be designed in a backwards compatible way!





Nokia Siemens Networks Researchers conducted theworld’s 1st demonstration of LTE-A technology (1.12.08)





LTE-Advanced Relay Demo





LTE-Advanced: 3GPP Work Item

3GPP has decided in May 2009 (TSG RAN#44)

• Changes to LTE-Advanced Study Item Description (RP-09066) – Include heterogeneous network deployments (Het-Net)

Support of heterogeneous network deployments i.e. mix deploymentsconsisting of macro, pico, femto and relay nodes

– Expected time scale for Study Item approval extended to March 2010

• Work Item structure – A work item should be created topic by topic

• Several LTE-Advanced Work Items will be created – Most work items to start in December 2009 and some e.g. Het-Net in

March 2010

– Release 10 functional freeze in December 2010 and ASN.1 freeze inMarch 2011 or in June 2011

Some advanced features could be postponed to Release 11





LTE-Advanced: Summary

• Bandwidth is extended up to 100MHz by using backwards compatible carrieraggregation

• Uplink SU-MIMO up to 4x4 for increasing uplink peak spectral efficiency (up to15bps/Hz) and enhance average cell spectral efficiency• Downlink MIMO enhancements

– Multi-user MIMO enhancements for better interference management usingcorrelated antennas

– Support of up to 8x8 MIMO to increase peak spectral efficiency (up to 30bps/Hz)and average cell spectral efficiency

• CoMP techniques are being studied for avoiding or converting co-channel inter-cellinterference into useful – Many options still on the table & some open issues in implementation and testing

• Relay Nodes using L3 wireless backhaul are being introduced for improving celledge performance.

• Local Area optimized features (in Release 11?)

– Autonomous Component Carrier Selection – Inband Inter-eNB Over-The-Air-Communication

=>With these techniques, the target of reaching a peak data rate of more than 1Gbit/s and improve average cell spectral efficiency by 50% in both UL and DLare achieved.





Thank you!

18 lte-advanced overview - tor leif aarland

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