Andreas RoesslerTechnology Manager North Americaandreas.roessler@rohde-schwarz.comRohde&Schwarz USA, Inc.

LTE for critical communications

APCO Broadband Summit 2014

Thanks to Wim – A short reflect to the previous talkHow to ensure VoLTE performance, incl. audio quality, battery life?

May 2014 LTE for critical communications 2

R&S®CMW500 Wideband Radio Communication Tester

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

Commercial vs. critical communication

ı Standards for commercial and critical communications 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 authorities,industry organizations.

� 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

May 2014 LTE for critical communications 3

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

May 2014 LTE for critical communications 4

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

May 2014 LTE for critical communications 5

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

E-UTRAN

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

May 2014 LTE for critical communications 6

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)

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

May 2014 LTE for critical communications 7

General challenges: Physical Channel Design for

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

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 feedback at all?

ı Power, power control?

ı Interference coordination/handling?

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

May 2014 LTE for critical communications 8

Cell 1

Cluster 1

Synchronization is prerequisite Different 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

May 2014 LTE for critical communications 9

Cluster 2

Synchronization Cluster Head (SCH)

? Where to synch too?

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)

May 2014 LTE for critical communications 10

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

May 2014 LTE for critical communications 11

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.

May 2014 LTE for critical communications 12

Thank you for

your attention!

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

African proverb