lte public safety technology evolution and testing...

LTE public safety

technology evolution and testing aspects

Reiner StuhlfauthTechnology Management & Marketing

ı There are different standards for commercial and critical communication.� Commercial cellular: vast success, economy of scale, high speed enables multimedia applications,

network capacity.

� Critical Communications: robust, group communication, priority control, direct mode.

� Commitment to LTE by U.S. authorities & industry organizations.

Commercial vs. critical & tactical communication

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

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

Requirements & Technical InputCellularIndustry LTE enhancements

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

May 2016 LTE public safety: technology & measurement aspects 2

Requirements for public safety in cellular world

Group communication

Video telephony anddatatransfer

Device to devicecommunication, D2D

Define priority rules

3GPP work items:• Direct Mode’ between terminals

(Discovery, Communication).• Group Communication.• Off network communication.• Push-To-Talk (PTT) including

group call / communication withlow call setup time.


Proximity Services ProSe: Direct Discovery, Direct Communication

SynchronizationDiscovery Communication

Align receiver window andfrequency correction whendetecting D2D channels.

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

proximity to detect each other

e.g. Group Call (VoIP)

Public Safety use case only

Source: Qualcomm (2012)


PS-LTE is band specific, e.g. possible bands discussed


E-UTRA ProSeBand

E-UTRA Operating

Band

ProSe UE transmit ProSe UE receive ProSeDuplex Mode

ProSe Direct

FUL_low – FUL_high FDL_low – FDL_high Disc. Comm.

2 2 1850 MHz – 1910 MHz 1850 MHz – 1910 MHz HD Yes

3 3 1710 MHz – 1785 MHz 1710 MHz – 1785 MHz HD Yes Yes







31 31 452.5 MHz – 457.5 MHz 452.5 MHz – 457.5 MHz HD Yes Yes


Source: 3GPP TS 36.101 V12.7.0 (March 2015)possible bands discussed in some regions

Scenarios for ProSe Direct CommunicationWithin network coverage

(Intra- / Inter-cell)Outside network

coveragePartial network

coverageNon-public

safetyDiscovery - -

Publicsafety

Discovery,Communication

Communication Communication

Sidelink

Downlink

UplinkSidelink

Sidelink


LTE Device-to-Device (D2D) Proximity Services (ProSe)

ı Current communication flow in LTE always involves the corenetwork:� Security reasons.� Policy control (Charging!)

E-UTRAN

EPCUE #1

UE #2

eNodeB

eNodeB UE – User Equipment (LTE-capable terminal)eNode B – evolved Node B (LTE base station)

EUTRAN – Evolved UMTS Terrestrial Radio Access NetworkEPC – Evolved Packet Core (core network)

EPS – Evolved Packet System (= EUTRAN + EPC)

ProSe = End to End communicationSidelink = channel structure


Overall LTE D2D ProSe Network Architecture

ı Network is still in charge!ı New interfaces, new

functional entities.� ProSe function, P3

interface: Authorization/ Provisioning, Request, Response.

� PC5 interface: one to many

8

UE B

ProSe

applicationLTE-Uu

E-UTRAN

UE A

S1

ProSe Function

MME

S/PGW

HSS

ProSe

application

HSS SLP

ProSe

Application

Server

S6a

PC3 PC4a PC4b

PC2

PC1

PC3

LTE-Uu PC5

PC1

Triggers use of Direct Discovery, Direct Communication

Authorizes and provision the device for ProSe

User Equipment (UE)

Mobile Equipment(ME)

UICC with USIM

Request

Response

Provision info can be storedon device (public safety, tactical comm.)


Direct Discovery – General PrincipleDiscovery Request and Response

ı Announcing and monitoring is possible in RRC_IDLE and RRC_CONNECTED state.

UE #2[Monitoring Device]

EPC

ProSeFunction

Discovery Request

DiscoveryResponse

DiscoveryResponse

Discovery Request

Transaction ID, Discovery Filter, Filter ID

Transaction ID, ProSeApplication ID, UE Identity (IMSI),

Command: Announce, Application ID

Transaction IDProSe Application Code,

Validity Timer etc.

Transaction ID, ProSeApplication ID, UE Identity (IMSI),Command: Monitor, Application ID

© Rohde&Schwarz 2015

UE #1[Announcing Device]


What is actually being ‘announced’ or ‘monitored’ by a device? Discovery Message

ı Two types of resource allocation for Direct Discovery: Type 1 and Type 2. � Discovery Message is transmitted on Physical Sidelink Discovery Channel (PSDCH), QPSK

modulation, 2 PRBs.

Message Type ProSe Application Code MIC UTC-based Counter LSB

8 bit 184 bit 32 bit 8 bit

232 bit

Open or Restricted discovery?Discovery Model?

(Rel.12 Model A only)


ProSe Security Parameters


PS-LTE has lots of security aspectscovered in the specification, e.g.

• ciphering & authentication• key handling• key negotiation

Device to device D2D: radio communication aspects

LTE direct communication

1 1 2 2 1 1 1 2 2 1

UE1UE2

Uplink LTE frequency band is used for D2DSC-FDMA scheme is used, Duplex mode is TDD

Normal CP

Extended CPCP CP CP CP CP CPOFDMSymbol

OFDMSymbol

OFDMSymbol

OFDMSymbol

OFDMSymbol

OFDMSymbol

1 2 3 4 5 6 7

1 frame à 10 msec

1 subframe à 1 msec

UE can negociateCP length

Last symbol in subframeIs skipped to enableRx-Tx switching


……

Resource Allocation for Direct Discovery, Direct Communication

ı A device is not required to simultaneously transmit D2D and WAN (generic LTE).

D2D D2D D2D D2D Bitmap Prose-SubframeBitmap-r12, e.g. 8 bit

PUCCH

PUCCH

cellular

cellular

e.g. DirectDiscovery

Resource Block Startprb-Start-r12

Resource Block Endprb-End-r12

Number of Resource Blocksprb-Num-r12

2015

©R

ohde

&S

chw

arz

cellular

e.g. DirectDiscovery

Number of Resource Blocksprb-Num-r12

Information provided bynewly introduced SystemInformation Blocks (SIB)

1 ms

Time


Overall process of Resource Allocation by the networkMode 1, eNB directly assigns transmission resources

UE #1

eNode B, EPC withProSe function

UE #2

DCI Format 5 on (E)PDCCH with CRC scrambled with SL-RNTI

SCI Format 0 on PSCCH

Data on PSSCH according to info in SCI Format 0, scrambled with Group Destination ID

SCI Format 0

Frequency hopping flag 1 bitRB Assignment and

hopping allocation

Num. of bits dependent on hopping active or not

Time Resource Pattern 7 bitModulation and Coding Scheme (MCS) 5 bit

Timing Advanced Indication 6 bitGroup Destination ID 8 bit

SIB Type 18 provides reception resource pool

2x

4x

SIB Type 18 acquisition

SidelinkUEInformation

RRCConnectionReconfiguration


ı For both scenarios, in-coverage (IC) and out-of-coverage (OoC), dependent on certain settings an UE can act as synchronization source transmitting synchronization signals and PBSCH.� Sidelink Synchronization Signal (SLSS) consists of Primary SLSS (PSSS), Secondary SLSS

(SSSS), similar to LTE Rel-8 downlink design. Periodicity is 40 ms.� PSBCH has same periodicity as SLSS. QPSK modulated, TBCC, 16-bit CRC.� Multiplexed into same RB as SLSS; see mapping principle, PSBCH carries Master Information Block

Sidelink (MIB-SL):� D2D System Frame Number (DFN), if UE in-coverage,

than DFN = SFN. DFN is 14 bit (10 bit + 4 bit offset). Subframe number [0…9].

� TDD UL-DL configuration [3 bit]. Reserved in case of FDD. � In-coverage bit [1 bit]. Bandwidth [3 bit]. � Reserved field [20 bit]. Set to a SIB-signaled or

preconfigured value in Rel-12.

1313 1313

Sidelink Synchronization Signals (SLSS), Physical Sidelink

Broadcast Channel (PSBCH) for Direct Communication

131211109876543210

Synchronization Subframe [1 ms], configured by higher layers

PSSS PSBCH SSSS GuardDMRS

6 R

esou

rce

Blo

cks


D2D: transmission of sync signals by a UE, 3 possible scenarios

Way 1: UE is instructed by network

please send syncsignal on allocated

ressources

Way 2: UE decision when in coverage

Way 3: UE decision when out of coverage

1. UE listensfor other UEs sync signals

2. UE transmitssync signals onpredefinedressources


Challenging Sidelink Synchronization Signal characteristicsPAPR, CM of Sidelink Synchronization Signals (SLSS)


CCDF, AM/AM and AM/PM of SLSS ID = 288

ı CCDF of measurement of SLSS ID = 288.

ı SLSS ID = 288 in FSW-K18 Power Amplifier measurement.


Outlook for Rel-13ı Mission Critical Push-To-Talk (MCPTT)


Remote

UERelay UE eNB

Public

Safety

ASPC5 Uu

EPC

SGi

Out- of-network

Always in coverage

in / out of coverage for

discovery and

selection

Discovery and (re-) Selection of Relay

UE

Protocol required

Control whether UE may act as a Relay

UE

ı UE as relay definition

ı Priority handling: group priority definition

ı Inter PLMN D2D communication

Testing of D2D/ProSe UEs

Integrate device emulation into CMW500; act as a network emulator and / or emulate device functionality.

Network link Sidelink (ProSe/D2D)

Testing UE signaling performance, protocol testing & application testing

Testing UE RF performance, e.g. Tx power, Rx sensitivity, modulation quality, throughput

Additional testing like e.g. Audio + video quality, battery drain, carrier acceptance tests, in-device interference aspects etc.


PS-LTE Drive Testing aspectsPosition Estimation of Base Stations

Coverage & Best server versus map

Automaticchannel detection


Drive testing aspects: Network performance analysis – statistic results l Network Performance

Analysisl Coveragel Interferencel Cell Problem Spots

l Neighborhood Analysis

l Handover Analysis

l Quality-of-Servicel Call Problem Spotsl Speech Quality

Analysisl Spectrum Analysis


Drive testing aspects: Network performance analysis – realtime results


LTE detailled analysis, e.g. interference detection & subband analysis

S-Synch (Power/SINR)P-Synch(Power/SINR)

72 SC (PBCH)(NB RSRPNB RSRQNB RS-SINR)

1 MHz = 62 SC

10 ms / 3 MHz FDD

5 ms => 200 Hz

Full Bandwidth e.g. 3 MHz � 180 SC (RSSI, WB RSRP, WB RSRQ, WB RS SINR)

Tx Antenna 1 (R0)Tx Antenna 2 (R1)

Interference canbe detected with WB measurements

Source of LTE grid: http://paul.wad.homepage.dk/LTE/lte_resource_grid.html

Subband

0

Subband

1

Subband

14

WB RS measurementsper subband(WB RS SINR)

All RS measurements (NB and WB) separately for R0 and R1

…

The „Achilless heel“ of LTE: Primary & Secondary Sync channel

should be at good SNR


Rohde & Schwarz LTE Test SolutionsCovering the full range of LTE & InterRAT test requirementsı LTE Device Testing

� R&D, Regression, Conformance, Operator Test Plans� RF, RRM, Protocol, IMS/VoLTE, Location Based Services� Over the Air Antenna Performance (TRP/TIS)� Mission Critical Communications

� High Power UE, Device-to-Device, etc.ı LTE Network Testing

� Installation, Maintenance, Drive Test, Benchmarking, Interference Hunting, Network Optimization, IP Analysis

ı Researching LTE Vulnerabilities� Unintentional / Intentional Jamming� Protocol Stack Manipulation

ı Researching Coexistence between LTE and other technologies� 40+ Bands of LTE FDD/TDD; InterRAT Performance� Radar + GNSS� WLAN, BT, GSM, CDMA, WCDMA, LTE


Rohde&Schwarz LTE/LTE-Advanced test solutions (device)

Signaling Conformance

R&S®CMW500including 3GPP

conformance tests

R&

S®T

S89

80S

yste

m

R&S®CMW500

Testing of- Protocol Layers- Operator Scenarios- E2E Application-Max. Throughput- IP4/6- MIMO- Handover

Signal Generator / Fading Simulator

R&S®FSW/FSQ/FSV(R)

R&S®SMW200A

One box Mobile Radio Tester for

Calibration, Verification and Functional Test

R&S®CMW500

RF, RRM Conformance, AGNSS& Data Performance

R&S®RTO

RF Development Protocol Stack Field Conformanceand Production and IOT Testing Testing

R&S®SMBV100

PowerMeter

R&S®NRP

Signal Analyzer

R&

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S-R

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S/P

QA

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SwissQualFreerider III

R&S TSME Ultra-compact Drive Test Scanner

SwissQualBenchmarker II

Field Test / Benchmark


Summary

ı LTE standard is currently extended to support critical and tactical communication.� “Direct Mode”, group control and out of network communication.

ı Stepwise approach, first features (Direct Discovery, Direct Communication) are added with 3GPP Release 12 and are further enhanced/extended with future release of the standard, e.g. Mission Critical Push To Talk (MCPTT) with Release 13.

ı Complexity of features requires new test strategies to verify conformance and performance of devices supporting Direct Discovery, Direct Communication. � Not only OEM’s are impacted, but also component manufacturers.

ı Rohde&Schwarz is your competent partner in solving these problems while offering adequate test solutions, e.g. R&S®CMW500 Wideband Radio Communication Tester.


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

African proverb


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