Leonard Tekes Workshop 15feb 2012

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Department nameRenesas Mobile Corporation

Rev. 0.00

2010 Renesas Mobile Corporation. All rights reserved.

2012/3/28

LTE on Shared Bands (LEONARD)

Kari Rikkinen

TEKES TRIAL seminar 15.02.2012


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Introduction

LTE on Shared Bands (LEONARD)

RME research project in Tekes Trial programme one of the parallel industry projects related to the CORE

project

duration 1.1.2011-31.12.2011 (an extension project included inTekes Trial programme in 2012)

Project focus

LTE technology applicability to shared band operation

LTE and WLAN technology coexistence in same frequency band

2 2010 Renesas Mobile Corporation. All rights reserved.


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LTE on Shared Bands - examples


*) *) ERC Dec 11(06)

IMT possible in 3.4-3.8 GHz


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Possible frequency bands for shared bandoperation with LTE technology

ISM 2.4GHz/ 5GHz Open for use if the regulation requirements are met (example of regulation requirements in Europe in separate

slide)

Unlicensed spectrum also available on frequency band below 1GHz (e.g. 902-928 MHz on ITU-R region 2)

Television White Spaces In general, TVWS spectrum (e.g., within 470-790 MHz band in Europe) can be one of suitable resources to

extend LTE systems operation Currently very diverse spectrum utilization opportunities (e.g. in Europe) Spectrum could be allocated for secondary use in spectrum blocks of N x TV channel bandwidth (N 1)

TV channel bandwidth 6 MHz in US, and 8 MHz in Europe

FCC has defined rules and regulations for operation No secondary system coexistence requirements (yet) Main intention is to protect the incumbent user

OFCOM has decided to make the TVWS license-exempt as long as the primary user is not interfered

Satellite Bands Satellite bands are seemingly an attractive option for shared band operation due to large amount of

spectrum allocated for different satellite systems However the protection of the incumbent users can be difficult in spectrum received for downlink (space-to-

earth) transmission In principle similar problem as with TV WS case (how secondary system would detect the location of

primary system receivers) Secondary operation is not currently allowed in satellite bands ?

New IMT-A Bands WRC-2007 identified new IMT-A bands beyond 3 GHz (3.4-3.6 GHz, 3.6-3.8 GHz) are suitable frequency

bands for local area/femto cell deployments No decision yet how these bands will be allocated to different operators, and thus not clear if there will be

any portion of the spectrum which shared between multiple operators/systems



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LTE on Shared Bands - Motivation

Why LTE technology based solutions for shared bands

Additional capacity to cellular system operation Increased capacity needs and shortage of licensed spectrum Opportunisticuse of additional capacity available on shared (e.g. unlicensed) bands

Using the same technology in licensed band and unlicensed band operationsimplifies system operation

New markets and development opportunities for LTE technology based

radio systems Deployment of LTE local area solutions to shared bands

Wireless broadband internet access, e.g., in rural areas

New applications and communication solutions for LTE modemtechnology

Machine to machine (M2M) communications

Vehicle to vehicle (V2V) or vehicle to infrastucture (V2I) communications

Ad-hoc networking of devices, mesh networks, short range communicationsetc



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Spectrum sharing principles

Spectrum sharing principles can be categorized e.g. as follows 1) :


Collaborative use of

IMT spectrum

(cellular operators)

Authorized spectrum

access (ASA)

ISM band usage Secondary usage of

TV White Space

spectrum

LEONARD focus

1) Peter Anker Cognitive Radio, the market and regulator, presentation, IEEE DySPAN 2010


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Regulations and specifications for devicesoperating in ISM band (Europe)

Additionally, devices operating in 2.4 GHz ISM band need to meet specifications as described in ETSI EN 300328 (latest spec version is V1.8.0, 2011-07), which defines requirements for data transmission equipmentoperating in the 2.4 GHz ISM band and using wide band modulation techniques EN300 328

wideband modulation based systems (other than frequency hopping based systems) need to provide spectrum sharingcapabilities either by non-continuous transmission (duty cycle requirements) or by some detect and avoid mechanism(separate requirements for listen before talk/non-listen before talk based detect and avoid solutions), or

can operate without any specific functional requirements for spectrum sharing if maximum rf output power level is lessthan 10 dBm


Regulatory requirements: ERC RECOMMENDATION 70-03 RELATING TO THE USE OF SHORT RANGE DEVICES (SRD), Annex 3: Wideband

Data Transmission systems


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Local area deployment environment on SharedBand (example case)

8

What modifications are needed to LTE to be able to claim that LTE system can

provide adequate spectrum sharing mechanism to facilitate sharing between variousradio access technologies *)

*) ERC RECOMMENDATION 70-03,


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Possible solutions to enable co-existence

A list of considered solutions to provideadditional capability to LTE technologybased system to coexist with other radio

access technologies Listen Before Talk

Sense the channel with LTE radio prior to thetransmission

Brute Force (Greedy) Operate without any coexistence concern

Detect and Avoid Interference detection, other RAT / same RAT

detection

Dynamic Frequency Agility

DFS (Dynamic Frequency Selection), DCS,Bandwidth scaling, extra carriers, etc..

Frequency Hopping LTE hops over a larger bandwidth and avoids

interfering

Hybrid Framing Use WLAN to reserve channel for LTE

Discontinuous Operation (time division) Transmission gaps to allow other technologies to

operate (different approach than LBT, here nosensing is done )

Higher Layer Coordination802.19.1 like approach where the coordination is left

for higher layers and radio changes are kept inminimum

Carrier Aggregation PCC on licensed band and SCC is used

opportunistically on shared band (ISM)


LTE Coexistence and Operation Features

Listen Before Talk

Brute Force

Detect and Avoid

Dynamic Frequency Agility

Frequency Hopping

Hybrid Framing

Discontinuous Operation (TimeDivision)

Higher Layer Coordination

Carrier Aggregation


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Alternative approaches (1) Higher layer coordination in LTE architecture


In general, central coexistence

unit (CCU) is necessary tocoordinate the RATs on sharedband.

Depending on the coexistencescenario, the central coexistenceunit can be implemented atnetwork management system(NMS) level, or at LTE core

network level. The central coexistence unit

consists of three elements:database, manager and gateway.

The central coexistence unit canprovide the coordinationdecisions for RATs, or justprovide the tunnels for the

coordination informationexchange at higher layer.

A: CCU can obtain the shared band information from external networks.B: CCU can obtain the shared band information through the spectrum sensing from thenodes/UEs.C: Inter/virtual MME connection for multiple LTE CNs (different operators)D: Virtual X2 connection for HeNBs.E: Interworking connection between LTE CN and other RAT network/AP(such as the Wa/Wnconnection for WLAN)F: Interworking connection between LTE CN and other RAT UE (such as Wu for WLAN)G: Connection to the CCU.

LTE CoreNetwork A

LTE UEA

LTE eNBA/shared

Externalnetworks(Internet)

Sharedbandinformation

Other WirelessNetwork(s) onshared band(Network/AP)

Other Wireless applicationUE

LTE CoreNetwork B

LTE UEB

LTE eNBB

A

B

C

D

E

F

G G

CentralCoexistenceUnit (CCU)


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Alternative approaches (2) Listen Before Talk - LTE

Listen-Before-Talk(LBT)or sometimes called Listen-Before-Transmit(orSpectrum OpportunityDetection)

A technique where atransmitter first senses its

radio environment before itstarts a transmission.

LBT in general can be usedby a radio device to find anetwork the device isallowed to operate on or tofind a free radio channel to

operate on Continuous transmission of

control channels requirespecial arrangements

The main principle of LBT-LTE illustrated in the figure



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Alternative approaches (3) Low Power LTE

In the Low Power LTEscheme the maximumtransmit power is limited to10 dBm No need for anyspecific spectrum sharingmechanisms to fulfillregulatory requirements for

ISM band operation.

Spectrum sensing anddynamic channel selectionmechanism is still beneficialto decide optimum spectrumresources for operation

Examples of spectrum usagewith low power LTE isillustrated in the figure



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Analysis Results Summary

In order to utilize current LTE on sharedbands with very minimal modifications

to the LTE radio protocol stack and airinterface the most suitable way wouldbe to use higher layer coordination.

Higher layer coordination would inpractice mean that LTE access point orthe LTE network is connected to acentral entity which allocates andmanages the spectrum utilization in agiven band.

An example of such central coordinationfunction would be 802.19.1 likefunction.

If such approach was taken the mainresearch questions would most probablybe above the radio layers, in LTE case in

the core network of an operator,possibly requiring multioperatorcooperation (connect the coordinationfunctions of different operators).


To complement the LTE with minimalchanges approach, new approaches

have been considered allowinguncoordinated operation on sharedbands while still aiming to utilize LTEphysical layer and protocol elements asfar as possible

Potential schemes include LTE with listenbefore talkfunctionality and a low powerLTE version with dynamic channelselection mechanism

Further work will include

Further development of LTE basedschemes for uncoordinated operation inshared bands

Performance analysis to verify and

demonstrate proper functionality of thenew concepts

Additionally, some of the new LBT/LTEprinciples may be able to verify withCWCs WARP platform as part of theCORE project collaboration

Leonard Tekes Workshop 15feb 2012

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