LTE for critical communications VT Wireless Symposium 05292014 · PDF fileLTE key parameter...

Andreas RoesslerTechnology Manager North [email protected]&Schwarz USA, Inc.

LTE – Fit for critical communications?!

Virginia Tech Wireless Symposium 2014

Outline

ı Who is Rohde&Schwarz and what do we do?

ı Fundamentals and basics of LTE.

ı LTE stands for Long Term Evolution, so what’s the e volution?� Overview of add-ons in LTE Release 9, 10 and 11.

ı LTE Release 12.� Proximity Services (ProSE) or Device-to-Device (D2D) Communication? � Group Communication System Enablers for LTE (GCSE).

ı Outlook Release 13.

ı Related Test & Measurement challenges.

ı Q&A, open discussion.

May 2014 LTE - Fit for critical communications? 2

Rohde & Schwarz at a glance

ı Founded in 1933 and headquartered in Munich, German y.

ı 9300 employees worldwide, 5650 in Germany.

ı FY 2012/13: $2.4 bn revenue.

ı Business fields:� Test & Measurement.� Broadcasting.� Secure Communication. � Radio monitoring.� Service.


Outline









Who is in charge?3rd Generation Partnership Project (3GPP)

5

Dec. 2008[Release 8]

June 2011[Release 10]

� http://www.3gpp.org

May 2014 LTE - Fit for critical communications?

June 2013[Release 11]

Dec. 2009[Release 9]

Rel-8

The LTEvolution pathHow does the standardization process works?

Rel-9Rel-10Rel-11Rel-12

today2014+2013+2015+2016+Commercialproducts

finished (12/2008)finished (12/2009)finished (06/2011)finished (06/2013)12/2014Anticipated completion

date in 3GPP*)

*) ASN.1 freeze

6May 2014 LTE - Fit for critical communications?

FDD versus TDD

Downlink

Uplink

Downlink and Uplink

Guard band required = Paired spectrum needed

Independent resources in uplink + downlink

Timing and DL-UL configuration required

No duplexer required!

Radio channel characteristics same

ı LTE FDD:

ı TD-LTE:


Band# Uplink (UL) operating band Downlink (DL) opera ting band

1 1920 MHz – 1980 MHz 2110 MHz – 2170 MHz

2 1850 MHz – 1910 MHz 1930 MHz – 1990 MHz

3 1710 MHz – 1785 MHz 1805 MHz – 1880 MHz

4 1710 MHz – 1755 MHz 2110 MHz – 2155 MHz

5 824 MHz – 849 MHz 869 MHz – 894MHz

6 830 MHz – 840 MHz 875 MHz – 885 MHz

7 2500 MHz – 2570 MHz 2620 MHz – 2690 MHz

8 880 MHz – 915 MHz 925 MHz – 960 MHz

9 1749.9 MHz – 1784.9 MHz 1844.9 MHz – 1879.9 MHz

10 1710 MHz – 1770 MHz 2110 MHz – 2170 MHz

11 1427.9 MHz – 1452.9 MHz 1475.9 MHz – 1500.9 MHz

12 698 MHz – 716 MHz 728 MHz – 746 MHz

13 777 MHz – 787 MHz 746 MHz – 756 MHz

14 788 MHz – 798 MHz 758 MHz – 768 MHz

17 704 MHz – 716 MHz 734 MHz – 746 MHz

18 815 MHz – 830 MHz 860 MHz – 875 MHz

19 830 MHz – 845 MHz 875 MHz – 890 MHz

20 832 MHz - 862 MHz 791 MHz - 821 MHz

21 1447.9 MHz - 1462.9 MHz 1495.9 MHz - 1510.9 MHz

22 3410 MHz - 3500 MHz 3510 MHz - 3600 MHz

23 2000 MHz – 2020 MHz 2180 MHz – 2200 MHz

24 1625.5 MHz – 1660.5 MHz 1525 MHz – 1560 MHz

25 1850 MHz – 1915 MHz 1930 MHz – 1995 MHz

26 814 MHz – 849 MHz 859 MHz – 894 MHz

27 807 MHz – 824 MHz 852 MHz – 869 MHz

28 703 MHz – 748 MHz 758 MHz – 803 MHz

29 – 716 MHz – 728 MHz

Public Safety (US)

PCS band (e.g. AT&T, Sprint)

AWS band (MetroPCS, T-Mobile,AT&T, Verizon, others)

UMTS850 MHz (e.g. AT&T)

e.g. US Cellular

Source: 3GPP TS 36.101 V11.2.0

Many frequency bands…for LTE FDD…

Lightsquared


…but for TDD too!

E-UTRAOperating

Band

Uplink (UL) BS receive UE transmit

Downlink (DL)BS transmit UE receive Region

FUL_low – FUL_high FDL_low – FDL_high

33 1900 MHz – 1920 MHz 1900 MHz – 1920 MHz Europe, Asia (not Japan)

34 2010 MHz – 2025 MHz 2010 MHz – 2025 MHz Europe, Asia

35 1850 MHz – 1910 MHz 1850 MHz – 1910 MHz US, Russia

36 1930 MHz – 1990 MHz 1930 MHz – 1990 MHz US

37 1910 MHz – 1930 MHz 1910 MHz – 1930 MHz former PCS band (US)

38 2570 MHz – 2620 MHz 2570 MHz – 2620 MHz Europe

39*) 1880 MHz – 1920 MHz 1880 MHz – 1920 MHz China

40 2300 MHz – 2400 MHz 2300 MHz – 2400 MHz China, Europe, India

41*) 2496 MHz – 2690 MHz 2496 MHz – 2690 MHz U.S.

42*) 3400 MHz – 3600 MHz 3400 MHz – 3600 MHz

43*) 3600 MHz – 3800 MHz 3600 MHz – 3800 MHz

44 703 MHz – 803 MHz 703 MHz – 803 MHz

*) LTE band only, no UTRA band

9May 2014 LTE - Fit for critical communications?

LTE key parameter (3GPP Release 8)

Frequency Range UMTS FDD bands and UMTS TDD bands (s ee previous slides)

Channel bandwidth 1 Resource Block (RB)=180 kHz

1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz

6 RB 15 RB 25 RB 50 RB 75 RB 100 RB

Modulation Schemes

Downlink QPSK, 16QAM, 64QAM

Uplink QPSK, 16QAM, 64QAM (� optional for handset)

Multiple AccessDownlink OFDMA (Orthogonal Frequency Division Multiple Access)

Uplink SC-FDMA (Single Carrier Frequency Division Multiple Access)

MIMO technology Downlink

Wide choice of MIMO configuration options for transmit diversity, spatial multiplexing, and cyclic delay diversity (max. 4 antennas at base station and handset)

Uplink Multi-user collaborative MIMO

Peak Data Rate(depending on UE category)

Downlink150 Mbps (UE category 4, 2x2 MIMO, 20 MHz)300 Mbps (UE category 5, 4x4 MIMO, 20 MHz)

Uplink 75 Mbps (20 MHz)


ı LTE is based on Orthogonal Frequency Division Multi plex (OFDM), which is a multi-carrier transmission technique, that divides the available spectrum into many subcarriers, each one being modulated by a low data rate stream.

ı Drawbacks of OFDM(A), the used transmission scheme in downlink:� High peak-to-average power ratio (PAPR).� Sensitive to frequency and clock offsets.

OFDM-based access schemes in LTEOFDMA as downlink transmission scheme (eNB � UE)

5 MHz

Single Carrier Transmission (e.g. WCDMA)

e.g. 5 MHz

180 kHz ��

12 subcarrier form a resource block (RB) = one or multiple RB are allocated to

a device for RX and TX

Typically several 100 sub-carriers with spacing of x kHz

In terms of data these subcarriers could be QPSK, 16QAM or 64QAM modulated

Subcarrier spacing in LTE is defined with 15 kHz

Downlink: 2 subcarrier per RB are used as reference signals (RS; called pilots in WiMAX)

Orthogonal Frequency Division Multiplex (OFDM)

2012 © by Rohde&Schwarz


eNB – LTE base stationUE – User Equipment

� DFT “pre-coding” is performed on modulated data symbols to transform them into frequency domain.

� Sub-carrier mapping allows flexible allocation of signal to available sub-carriers.,� IFFT and cyclic prefix (CP) insertion as in generic OFDM.

� Each subcarrier carries a portion of superposed DFT spread data symbols, therefore SC-FDMA is also referred to as DFT-spread-OFDM (DFT-s-OFDM).

� Advantage: lower PAPR than OFDM, but modulation scheme dependent.

OFDM-based access schemes in LTESC-FDMA as uplink transmission scheme (eNB UE)

Time DomainFrequency DomainTime Domain

……

……

……

……

……

….

..……

……

….

coded symbol rate R

NTX symbols

N-pointDFT

SubcarrierMapping

Parallel/S

erial

M-pointIDFT

CP Insertion

Same as OFDM



E-UTRAN

SLs

S11

Evolved Packet System (EPS)

l The term ‘LTE’ stands for a new air interface (E-UT RAN), where non-radio aspects are covered within the so called ‘Sys tem Architecture Evolution’ (SAE) summarized as Evolved Packet Core (EPC).l E-UTRAN + EPC = Evolved Packet System (EPS). l All interfaces are IP-based and standardized to allow multi-vendor

interoperability.

UE = User Equipment eNodeB = evolved Node B S-GW = Serving Gateway P-GW = Packet Data Network (PDN) Gateway MME = Mobility Management Entity PCRF = Policy Control and Routing FunctionHSS = Home Subscriber Server E-SMLC = Evolved Serving Mobile Location Center GMLC = Gateway Mobile Location Centre IMS = IP Multimedia Subsystem E-UTRAN = Evolved UMTS Terrestrial Radio Access Network

EPC

HSS

GMLCE-SMLC

MME PCRF

SLg S6a

Gx Rx

S1-MME

S1-U S5/S8 SGiUUS-GW P-GWUser

Equipment eNodeBOperator’s IP

services (e.g. IMS)

IP data transportSignaling interface


Non-Access Stratum (NAS)

Evolved Packet System (EPS)

l Functional split between E-UTRAN (eNB) and EPC (foc us: MME).

E-UTRAN = Evolved UMTS Terrestrial Radio Access Network eNB = evolved Node B MME = Mobility Management EntityRRM = Radio Resource Management RB = Radio Bearer RRC = Radio Resource ControlPDCP = Packet Data Convergence Protocol RLC = Radio Link Control MAC = Medium Access ControlPHY = Physical Layer NAS = Non Access Stratum AS = Access Stratum

Access Stratum (AS)

Terminal (UE)


UU S1 S5/S8 Gi

l EPS has been designed to be “All IP”-based, thus su pports only packet switched (PS) services, targeting seamless s ervice continuity. l EPS uses concept of EPS

bearer to route the IP traffic from Packet Data Network (PDN, e.g. internet) to the terminal (User Equipment, UE).

l A bearer is an IP packet flow, with a fully defined Quality of Service (QoS).– Bearers are grouped into 2 categories, due their associated QoS: minimum

guaranteed bit rate (GBR, e.g. VoIP) and non-GBR bearer (e.g. FTP download).– eNodeB’s responsibility to ensure QoS parameters are met over the air interface.– QoS authorization (QoS class identifier, bit rates) is provided by PCRF, which decides

how data flow is treated by Policy Control Enforcement Function (PCEF), that resides in the P-GW.

EPS bearer service architecture


EPS bearer characterization

l QCI = QoS Class Identifier.– Characterized by a priority, packet delay budget, acceptable packet loss rate.– Determine RLC mode (AM, UM), MAC scheduling (priority, queue management).

l ARP = Allocation and Retention Priority.– Shall the bearer be established in case of radio congestion?

QCI Type PriorityPacket Delay Budget [ms]

Packet Error Loss Rate

Example Service

1

GBR

2 100 10-2 Conversational voice

2 4 150 10-3 Video (live streaming)

3 5 300 10-6 Video (buffered streaming)

4 3 50 10-3 Real-time gaming

5

Non-GBR

1 100 10-6 (IMS) Signaling

6 7 100 10-3Voice, video (live streaming),

interactive gaming

7 6 300 10-6 Video (buffered streaming)

8 8 300 10-6TCP-based (i.e. www, email),

chat, FTP, p2p file sharing

9 9 300 10-6


By the way, how is voice supported in LTE?Voice (and SMS) over LTE (VoLTE)

l Voice is key for critical communications! How does it work in LTE? l LTE has been designed as a fully packet-orientated, “all-IP”-based, multi-

service system with a flat network architecture. – Technical challenges offering circuit-switched services (Voice, SMS) via LTE due to

no connection to circuit switched domain (CS domain).

GERAN

UTRAN PS domain PDN

CS domain PSTN / PLMN

E-UTRAN EPC

IMS

??


What is IMS?A high level summary, cont’d.

l IMS is specified by 3GPP, describing an overall arc hitecture and the interaction with Radio Access Networks (RAN); b ased on Internet Engineering Task Force (IETF) defined stan dards and protocols.

l IMS requires direct message/content flow from/to UE , between UEs.l In 3G: UE is assigned with private IP address, traffic is routed by the network.l Problem: UE are not addressable from outside the wireless network.l Solution: IPv6, to assign every network node with an IP address. l IMS originally defined for IPv6 only, then IPv4 support added.

l Introduction of “All-IP” architecture requires IPse c to ensure secured communication.


IMS is an overlay to the existing LTE network

Session management and routing functionality

Databases Services Interworking Support

AccessIndependent!

IMS uses Internet Protocols (IP); protocol structure

UtilitiesMedia TransportSignaling

ApplicationLayer

TransportLayer

NetworkLayer

AccessTechnology LTE

IPv4, IPv6

TCP UDP

RTSPSIP RCTP DNS DHCP

SDP

RTP

MediaEncoding

SDP – Session Description Protocol RTSP – Real-Time Streaming Protocol SIP – Session Initiation ProtocolRTP – Real-Time Transport Protocol RTCP – Real-Time Control Protocol DNS – Domain Name ServerDHCP - Dynamic Host Configuration Protocol TCP – Transport Control Protocol UDP – User Datagram Protocol



Reduce complexity of IMS to enable voice and SMS delivery – Industry agreed on an IMS profile

Source: http://www.gsma.com/newsroom/wp-content/uploads/2013/04/IR.92-v7.0.pdf

Protocol, air interface and radio aspects of VoLTE

ı Support of multiple EPS bearers to support IMS traffic and signaling (SIP).� Dedicated radio bearers for IMS signaling (SIP), voice, video.

ı As all is IP-based there is a need for overall packet size reduction (e.g. packet header) and efficient coding.� Robust Header Compression (RoHC) for compression of IP packets.

� Different RoHC profiles.

ı PHY/MAC features affecting VoLTE.� Transmission Time Interval (TTI) bundling to reduce UL load.

� Device can autonomously retransmit data packets within a bundle of four subframes without awaiting ACK/NACK.

� Semi-persistent scheduling.� Device uses a pre-defined resource for RX and/or TX.� Discontinuous Reception (DRX).


Further reading and information


Outline









eMBMSenhancements

Positioning

Dual LayerBeamforming

Multi carrier /Multi-RAT

Base Stations

Home eNodeB

Self OrganizingNetworks

Public WarningSystem (PWS)

Enhancements for LTE with Release 9Rel-9

LTE Release 8FDD / TDD


eMBMSenhancements

Positioning



Base Stations

Home eNodeB



RelayingSON

enhancements

CarrierAggregation

DL MIMO8x8

EnhancedSC-FDMA

eICIC

UL MIMO2x2

Pimp my LTEBecoming a “True 4G” technology

Rel-10

Rel-9


To achieve peak data rates and spectral efficiencyin Downlink and Uplink based on IMT-Advanced requirements to become a true 4G technology!


And there is Release 11…


Rel-10

Rel-9

Enh. DL Control CH

NetworkEnergy Saving

CoMP UL / DL

In-deviceco-existence

RAN enh. forDiverse DataApplication

RAN overloadcontrol for MTC

feICIC(further eICIC)

Service Continuityfor eMBMS

CAenhancements

NW-based positioning

(UTDOA)

MDT

Rel-11

Relaying

SONenhancements

CarrierAggregation

DL MIMO8x8

EnhancedSC-FDMA

eICIC

UL MIMO4x4

eMBMSenhancements

Positioning



Base Stations

Home eNodeB




Commercial vs. critical communication

ı Standards for commercial and critical communication s have been separate.� Commercial cellular: vast success, economy of scale, high speed (broadband) enables

multimedia, network capacity.

� Critical communications: robust, group operation, priority control, direct mode.

ı Commitment to LTE by authoritiesand industry organizations.� E.g.: MoA between NPSTC

and TCCA in July 2012.

� not optimized for critical communications, no strong coverage obligations.

� Expensive due to limited volume, slower evolution than commercial cellular

CellularIndustry

Source: LTE Standards for Public Safety – 3GPP view , Balazs Bertenyi. Chairman 3GPP TSG SA at Critical Communications World, May 2013

LTE enhancements


OK, let’s built a network…


But seriously, what are the challenges?

ı Commercial mobile networks offer…� Robust support for mobility. � Security.� Quality-of-Service (QoS) and priority

mechanisms, including preemption. � Reliability (shared testing efforts, IOT).� Possibility of shared commercial and

public safety networks. � Shared infrastructure costs for wide-area

coverage.� Public safety traffic could be prioritized.

ı Public safety communication systems require…� Reliability and Resilience. Functioning

satisfactorily over periods and under adverse circumstances.

� Push-To-Talk (PTT) and group call / communication with low call setup time.

� Direct communication between terminals.

� Off network communication.


Study Item, Work Item 3GPP Rel. Status Reference

Public Safety Broadband High Power User Equipment (HPUE) for Band 14 for Region 2

11 FinishedRP-120362RP-130949

Study on Proximity-based Services (ProSe) 12 Finished TR 22.803

Group Communication System Enablers for LTE

12 OngoingTS 22.468TS 23.468

Proximity-based Services (ProSe) 12 OngoingTS 22.278TS 23.303

Study on LTE Device to DeviceProximity Services, Radio aspects

12 Finished TR 36.843

Study on Group Communication 12 Finished TR 36.868

Study on Isolated E-UTRAN operation for public safety 13 Ongoing TR 22.897

Mission Critical Push-To-Talk over LTE 13 Ongoing TS 22.179

Isolated E-UTRAN operation for public safety 13 Ongoing TS 22.278

Proposal: Study on inclusion of Terrestrial Beacon Systems (TBS) in LTE

??? Postponed RP-140446

Public Safety in LTE


Source: http://www.3gpp.org/ftp/Information/WORK_PLAN/Description_Releases/LTE%20for%20Public%20Safety%20(authority-to-authority)%20communications_20140316.zip

High-Power User Equipment (HPUE) demonstration

at Mobile World Congress 2014 Barcelona/SPAIN


R&S®CMW500 Wideband Radio Communication Tester

+ +

6.2.2_1 Maximum Output Power for HPUE

6.2.3_1 Maximum Power Reduction (MPR) for HPUE

6.2.4_1 Additional Maximum Power Reduction (A-MPR) for HPUE

6.2.5_1 Configured UE transmitted Output Power for HPUE

6.3.5_1.1 Power Control Absolute power tolerance for HPUE

6.3.5_1.2 Power Control Relative power tolerance for HPUE

6.3.5_1.3 Aggregate power control tolerance for HPUE

6.6.2.3_1 Adjacent Channel Leakage power Ratio for HPUE

Commercial:+23 dBm

HPUE:+31 dBm[for Bd.14 only]

HPUE live demo and much more…Outside this building, in the parking lot


Real-time spectrumanalysis

Radio monitoringand location

Spectrum capture

Band 14 High-Power

UE demo

Ch68

770

Ch63

Ch52

Ch53

Ch54

Ch55

Ch56

Ch57

Ch58

Ch59

Ch60

Ch61

Ch62

Ch64

Ch65

Ch66

Ch67

Ch69

Why additional RF tests for HPUE?700 MHz Spectrum


A[Uplink]

B[Uplink]

C[Uplink]

D[Uplink]

E[Uplink]

A[Downlink]

B[Downlink]

C[Downlink]

D[Downlink] PSNB

Public Safety

C[Uplink]

704 710 716 722 728 734 740 752 758 764 776 782 788 794 800

787 793 798777757

Lower 700 MHz

Band 17 Band 29 Band 17

Band 12 Band 12

Band 13 Band 13

768

769

763

C[Downlink]

A

805

[Downlink only]

Upper 700 MHz

GB

PSBB

A D[Uplink] PSNB

Public Safety

GB

PSBB

B

775 799

PSBB – Public Safety BroadbandPSNB – Public Safety Narrowband

GB – Guard Band

B

Ch64

775

Ch68

770

Ch63

Ch52

Ch53

Ch54

Ch55

Ch56

Ch57

Ch58

Ch59

Ch60

Ch61

Ch62

Ch65

Ch66

Ch67

Ch69

Why additional RF tests for HPUE?700 MHz Spectrum (cont’d.)


A[Uplink]

B[Uplink]

C[Uplink]

D[Uplink]

E[Uplink]

A[Downlink]

B[Downlink]

C[Downlink] PSNB

Public Safety

C[Uplink]

704 710 716 722 728 734 740 752 764 776 782 794 800

787 793777757

Lower 700 MHz

Band 17 Band 29 Band 17

Band 12 Band 12

Band 13 Band 13

769

763

C[Downlink]

A

805

[Downlink only]

Upper 700 MHz

GB

A

PSNB

Public Safety

GB

BB

PSBB – Public Safety BroadbandPSNB – Public Safety Narrowband

GB – Guard Band

799

Band 14Band 14

758 788

798768

D[Downlink] PSBB

D[Uplink] PSBB

Outline









E-UTRAN

Proximity Services / Device-to-Device communicationUnderlying problem: Current communication flow in LTE


EPCUE #1

UE #2

eNodeB

eNodeBUE – User Equipment (LTE-capable terminal)

eNode B – evolved Node B (LTE base station)EUTRAN – Evolved UMTS Terrestrial Radio Access Network

EPC – Evolved Packet Core (core network)EPS – Evolved Packet System (= EUTRAN + EPC)

Why Proximity Services and Group Call in LTE?Use case and priorities

ı Use cases were outlined by U.S. Department of Comme rce *).� A Public Safety ProSe-enabled UE whether or not it is served by

E-UTRAN shall be capable of receiving a ProSe Group Communications transmission, of which it is a group member, regardless of whether or not it has been discovered by the transmitting Public Safety ProSe-enabled UE.

� Authorised Public Safety ProSe-enabled UEs, whether being served or not by E-UTRAN, shall be able to communicate with other authorised Public Safety ProSe-enabled UEs whether or not ProSe discovery is used.

� Subject to operator policy and/or network authorization, a user of a Public Safety ProSe-enabled UE shall be able to select the ProSe Communication path (direct or routed via local eNb) when the Public Safety ProSe-enabled UE is being served by E-UTRAN. This requirement applies to any ProSe E-UTRA Communication between two Public Safety ProSe-enabled UEs, ProSe Group Communication and ProSe Broadcast Communications. The network authorization shall consider the current traffic condition in the specific area.

ı Covered in 3GPP TS 22.278 V12.4.0 (2013-09).


*) RAN WG1 #74 R1-133186 (August 2013)

Proximity Services (ProSE) and D2D – Just another

acronym?ı Proximity Services (ProSE) is also understood as De vice-to-Device

communication (D2D).� Two sub-features: (1) D2D discovery and (2) D2D communication.� Synchronization of devices is essential and pre-requisite.

ı Feature targets consumer and non-commercial markets (i.e. public safety).� File transfer, advanced social networking, targeted advertising. � Communication between devices, even if w/o network coverage.

ı Initially two slightly different approaches.� “LTE direct” – exclusively using LTE (spectrum) for discovery, communication.� “LTE/WiFi direct” – authentication/authorization for direct communication via i.e. LTE,

communication between devices based on WLAN (WiFi direct). � LTE: working assumption in RAN1 to use uplink spectrum for the D2D link.


Source: RAN WG1#73; 3GPP TS 22.278 V12.4.0, section 7A

Intended communication flowCommercial use case


EPC

Network-assisted discovery

Direct communicationorUE #1

UE #2

eNodeB

eNodeB

1

2

Important: there is interested on the commercial side


What’s the potential interest?Mobile Advertising


Discussed scenarios for ProSE / D2D

1 UE #1, UE #2: no coverage

UE #1 UE #2

2 UE #1 in coverage, UE #2 out of coverage

UE #1 UE #2

3 UE #1, UE #2: in coverage (single cell)

UE #1 UE #2

4 UE #1, UE #2: in coverage (multiple cell)

UE #1 UE #2


! RAN1: scenario only allowedfor public safety use case!

Discovery for in-coverageprioritized by RAN plenary!

UE to UE relayOut-of-coverage scenario, public safety only


UE #1 UE #2 UE #3

Relay

ProSE architecture


UE

ProSe APP

LTE-Uu

E -UTRAN

UE

ProSe APP

EPC

S1

ProSe APP

Server

SGi

ProSe Function

PC4

PC2

PC5 LTE-Uu

PC3

PC1

PC6

The triggerThe trigger

Definition of ProSE discovery and communication

ı ProSE discovery.� Under control by the network operator, authorized on a “per UE” and/or “per UE per

application” basis. Network controls the resources used for discovery.� ProSE discovery is not necessarily followed by ProSE communication.

ı ProSE communication.� Enables communication path between two or more ProSE-enabled UE’s.� The network may switch between an EPC and ProSE communication path; an EPC and

ProSE communication path could also be active at the same time.� For specific public safety use case:

� ProSE communication can start w/o discovery if UE’s are in communication range.� Authorization by operator required. Public Safety ProSE-enable UE’s need to be able to

participate in group and broadcast communication regardless if they are served by NW.� ProSE communication also supports ProSE UE-to-NW relay.

� Single mechanism for 1:1, 1:M communication both for in- and out-of-coverage.

Source: 3GPP TS 22.278 V12.3.0 Service requirements for Evolved Packet System (EPS) (June 2013)


ı Unicast: 1 st UE is transmitter, 2 nd UE is receiver.ı Relay (partial coverage scenario:1st UE without eNB c overage, 2nd UE

within eNB coverage).ı Groupcast: One UE to many (= Y) UE’s within one gro up. ı Broadcast: One UE to all.

Within networkcoverage

Outside networkcoverage

Partial networkcoverage

DiscoveryNon public safety &

public safetyrequirements

Public safety onlyPublic safety only

DirectCommunication

At least publicsafety requirements

Public safety only Public safety only

RAN1 issues: general challengesScenarios, simulation assumptions


Public Safety only!

Added atRAN1#72

General challenges: Physical Channel Design for

ProSe / D2Dı Is D2D link based on today’s LTE physical channel d esign?

ı If yes, Downlink or Uplink (OFDMA vs. SC-FDMA)?� Today’s working assumption in 3GPP: reuse of uplink structure / spectrum.

ı How are the resources scheduled? What about MCS/TBS selection?

ı HARQ: How is feedback managed? Is there any feedbac k at all?

ı Power, power control?

ı Interference coordination/handling?

ı Method of multiplexing between D2D link and U u (= LTE air interface)?


Synchronization Discovery Communication

Align receiver window andfrequency correction when

detecting D2D channels.

Align transmitter timingand parameters when

transmitting D2D channels.

Power efficient mechanism fortwo (or multiple) UE’s in

proximity to detect each other

e.g. Group Call (VoIP)

Way forward: ProSE / D2D Communication steps


Cell 1

Cluster 1

Synchronization is prerequisiteDifferent synchronization sources are possible dependent on scenario

Synchronization Cluster Head (SCH)

Cell 2

eNodeB

eNodeB

Source: R1-135803 Synchronization Procedures for D2D Discovery and Communication, Ericsson [Nov.2013]

D2DSS

D2DSS


Cluster 2

Synchronization Cluster Head (SCH)

? Where to synch too?

Public safety use case a UE out-of coverage may assume the SCH role autonomously.

Synchronization and Timing for D2DCont’d., Qualcomm proposal (one of many contributions!)


Source: R1-133598 Techniques for Synchronization [Qualcomm], RAN WG1#74 (Aug.2013)

1 sec 1 sec 1 sec

Synchronization Radio Frame

10 ms

SF0 SF1 SF2 SF3 SF4 SF5 SF6 SF7 SF8 SF9

0 1 2 3 4 5 6 0 1 2 3 4 5 6

Time Slot0.5 ms

Time Slot0.5 ms

D2D Synchronization Signal (D2DSS), Discussion on Primary D2DSS (Zadoff-Chu sequence), Secondary D2DSS (M sequence)

OFDM symbol

Guard Symbol

PD2DSCH may provide:• Identity of Synchronization Source• Type of Synchronization Source• Resource Allocation for data

and control signaling• Data. other (FFS)

How devices are discovered?Qualcomm proposal: Expressions*) (one of many contributions)

ı Two types of discovery:� Type 1: discovery resources are allocated on a non-UE specific basis. In-coverage

these resources are allocated by the eNB. FFS � Type 2: discovery resources are allocated on a per-UE specific basis.

� Type 2A: allocated for each specific occasion. � Type 2B: semi-persistent allocation.

ı “Expressions” are used to discover services, applicat ions and context in close proximity. They are further used to establish direct communication. � Expression code could be used either ‘public’ or ‘private’:

� ‘Public’ – ShirtSale@FashionShop� ‘Private’ – JohnDoe @Starbucks

� An “Expression” (= MAC PDU) corresponds to 128-bits at the PHY layer (104 for expression, 16 or 24 CRC). Turbo code is used if MAC PDU is not smaller then 104.

ı An UE transmits/receives these “expression(s)” in ‘di scovery resources’.� ‘Discovery resources’ may be assigned via SIB (commercial use case).

*) Sources: Qualcomm presentation, TR 36.843 V12.0.1 (2014-03), section 8.2.1


ı Discovery Resources: LTE uplink spectrum is used i. e. 64 ms every 20 s using 44 RB.

64 ms

Example: device discoverySource: Qualcomm proposal (one of many contributions)

20 s

Direct Discovery Resources (DRID)

LTE Uplink

10 M

Hz

(50

RB

)

Subframe = 1 ms

…..…

….…

.

0

…….………….01

43

…..…

….…

.

63

…..…

….…

.

1

…..…

….…

.

0

………..…..….

…..…

….…

.

63

…..…

….…

.

1

…..…

….…

.

0

…..…

….…

.

63

…..…

….…

.

1

………..…..….

………..…..….………..…..….………..…..….t = 0 t = 1 t = 63

Apply Hopping sequence

*) Source: LTE Direct Overview, Sajith Balraj, Qualcomm Research


D2D communication link

ı Application focus: (Group) voice call (VoIP). � See Traffic Model in TR 36.843, section A.2.1.3

ı Proposal: simplified design similar to TETRA DMO.� Reuse PUSCH architecture as much as possible.� MCS is fixed (e.g. QPSK, RC= ½).� No physical layer feedback (focus on broadcast communication).

� Blind HARQ retransmission to improve reliability.


Group Communication System

Enablers for LTE (3GPP Release 12)


Media traffic with unicast and MBMS on DownlinkUplink unicast only


Cells (eNB) could belong to same MBSFN area

Source: 3GPP TS 23.468 V12.0.0 (2014-02) Group Communication System Enablers for LTE (GCSE_LTE), Stage 2

New functional interfaces are requiredNon-roaming case


UE

GCS AS

BM-SCE-UTRANM1

S/P -GW

MBMS-GW

SGmb

SGimb

MME

HSS

S 6a

Uu

PCRF

Gx

GC1

S1-u

S 1- MME

S- 11

M3Sm

SGi

MB2-C

Applicationdomain

Rx

H-PLMN

MB2-U

GCSE requirements for RAN

ı User may be member of more than one group and commu nicate to several groups in parallel

� e.g. voice to one group, video to other groups� e.g. different hierarchy levels

ı Performance requirements:� End-to-end setup time <= 300 ms

� Provided no ack of group members needed

� Time to join existing group comm. <= 300 ms� End-to-end data delay <= 150 ms

ı Scalability: Max group size FFSı Service continuity when UE moves among cells during communicationı Priority: Support of pre-emption of lower priority communication


Based on reqs for legacyTETRA mission criticalvoice systems

GCSE Transmission Model


DedicatedUL

DL eMBMS DedicatedServiceContinuity?

Many UEs in one cell☺ Scalability

☻ Long setup time☻ pre-configuration

☻Not always available

Few UEs in one cell☺ Fast setup time☺ Always available

☻ Bearer handling on long idle time☻ Keep or stop?

Planned & corrected timeline for 3GPP Release 12

ı Presented by 3GPP at Critical Communications Europe (March 2014).


Outline









Several study items related to public safety in Rel-13

ı Isolated E-UTRAN Operation for Public Safety.� Study on network operation when backhaul link

to the core network is not available. � Locally routed communication.

ı Mission Critical Push To Talk over LTE (MCPTT).� Specify Stage 1 requirements for a PTT functionality to support mission critical voice

communication over LTE that can be used by public safety and commercial (e.g. utility companies, railways).


Anticipated timeline for 3GPP Release 13


ı Presented by 3GPP at Critical Communications Europe (March 2014).

Outline









VoLTE performance is critical for public safetyReliability, audio quality, power consumption



R&S®NGMO2 Power Supply

R&

S®

UP

V A

udio

Ana

lyze

r

RF link To/from head jack

Measure current drain

LTE network emulation, e.g.

Band 14

…incl.IMS …incl. audio

codec (e.g. AMR-WB/NB)

…incl. IPimpairments

…incl.DRX

So is HD voice (AMR-WB) really making a

difference? Oh, yes…


ı AMR-WB defined by 3GPP, adopted for public safety:

Source: http://www.its.bldrdoc.gov/publications/2693.aspx

Where to start for D2D? Physical Layer (PHY/L1) testing!

ı Synchronization. � Verify synchronization/timing principle for D2D.

ı Verify discovery methodology.

ı Verify D2D communication link. � New or modified control channel / signaling procedures?� New or modified data channels?� New or modified DMRS?� Resource scheduling? MCS/TBS selection?� HARQ, feedback…� Power, power control…


Open-loop PHY/L1 testingCheck synchronization


Generate D2DSS, PD2DSCH

Analyze D2DSS, PD2DSCH

R&S®FSW Signal and Spectrum Analyzer

R&S®SMW200A Vector Signal Generator

Pro

SE

-ena

bled

UE

Pro

SE

-ena

bled

UE

Vector Signal generator assumes role of Synchronization

Cluster Head (SCH)

ProSE-enabled DUTassumes role of Synchronization

Cluster Head (SCH)

Open-loop PHY/L1 testingCheck discovery


Generate discovery beacon


Pro

SE

-ena

bled

UE

Vector Signal generator Plays an ARB file that

Simulates multiple discovery beacons?

Open-loop PHY/L1 testingVerify D2D communication link


Provide D2D link / data

Analyze/demod. D2D link

R&S®FSW Signal and Spectrum Analyzer


Pro

SE

-ena

bled

UE

Pro

SE

-ena

bled

UE

“Receive mode”

“Transmit mode”


R&S®CMW500 Wideband Radio Communication Tester Configured as Multi-RAT protocol tester

R&S®CMW500 WidebandRadio Communication Tester

Configured as Call Box for RF parametric testing

Introduction to Rohde&Schwarz R&S®CMW500

Wideband Radio Communication Tester

Closed-loop PHY/L1 testing


Pro

SE

-ena

bled

UE

D2D Discovery, D2D synchronizationD2D communication


Authorization? At this point a minor issue…


LTE RF link

i.e. Bd.14

Develop MLAPI-based testcases for network-assisteddiscovery i.e. authorization,decline authorization, deny access…

ProSE-enabled UE under test

Concurrent D2D link and network link


Integrate device emulation into CMW500; act as a networkemulator and emulate devicefunctionality both in parallel?

Network linki.e. Bd. 14

D2D linki.e. Uplink Bd. 14



Locally routed communication flow with proximity

service


Integrate device emulation into CMW500; act as a networkemulator and emulate UE#1functionality in parallel.

CMW500



UE to network relay (out-of-coverage situation)


“Relay Link”

Bd. 14 Uplink

Emulate UE in coverage toverify communication link toUE out of coverage.

CMW500

ProSE-enabled UE under test R&S®CMW500 Wideband Radio Communication Tester

Summary & conclusion

ı Release 11 adds first feature for public safety: Hi gh-Power UE (HPUE).� Testing today possible using R&S®CMW500 Wideband Radio Communication Tester.

ı With 3GPP Release 12 LTE will be enhanced to suppor t features demanded for critical communications / public safet y. � Proximity Services (ProSe), Device-to-Device (D2D) communication.� Group Communication System Enablers for LTE (GCSE_LTE).

ı However, still a lot of questions to be answered. � Standardization to be “finished” by end of 2014; implementations typically available 18

to 24 months after.

ı More features to come with 3GPP Release 13.

ı Rohde&Schwarz monitors standardization process very c losely and cooperates with key industry players to enable test ing of ProSe, GCSE.


…and don’t forget to spend us a visit


Real-time spectrumanalysis

Radio monitoringand location

Spectrum capture

Band 14 High-Power

UE demo

Thank you for

your attention!

“If you want to go fast, go alone. If you want to go far, go together!”

African proverb


References

[1] 3GPP TR 36.843 V12.0.1 (2014-03), Study on LTE D evice to Device Proximity Services; Radio Aspects.

[2] LTE for Public Safety (authority-to-authority) c ommunications V0.0.2 (2014-02);


LTE for critical communications VT Wireless Symposium 05292014 · PDF fileLTE key parameter...

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Transcript of LTE for critical communications VT Wireless Symposium 05292014 · PDF fileLTE key parameter...