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“PROXIMITY SERVICE EVALUATION & EXTENSIONS”

IMPROVING BROADBAND DIRECT COMMUNICATIONS

PSCR Grant Funded (Commerce Dept.) 

10 July 2019
2

DISCLAIMER

This presentation was produced by guest speaker(s) 

and presented at the National Institute of Standards 

and Technology’s 2019 Public Safety Broadband 

Stakeholder Meeting. The contents of this 

presentation do not necessarily reflect the views or 

policies of the National Institute of Standards and 

Technology or the U.S. Government.

Posted with permission
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 3 TM

PSIAP ProSe

Key success factors

Description/ key features

Market

• Matching or exceeding the reliability and coverage of existing LMR direct communication 

capabilities

• Enabling new services with ease of use, continuity across network domains, and data services

• Satisfying current and future direct communications requirements for First Responders 

• Direct communication is required for all public safety communication systems

• ProSe is the only broadband direct communication standard designed to address this requirement

• The size of the public safety market has limited enabling hardware (chip sets)
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 4 TM

Group domain types

Network

Extension

Relay

Groups can fragment and reconnect

Network group

Direct group

Hybrid group

Not efficient in good network coverage

Network communications provides:

• Greater efficiency

• Less congestion limitations

• Connections for 

‒ Reporting chain monitoring

‒ Evidentiary recording
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 5 TM

The direct communications use cases

Close communication in hostile situations

• SWAT/ Building fires

No macro network

• Local macro network down

• In-building

• Remote locations: public safety/ wild fire

• Immediate geography: gulley/ obstructions: buildings

LTE direct

LTE direct with relay
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 6 TM

LTE/5G-direct standards development/ releases

R11 High Power UE for B14: March 2013

R12 Study/ Initial ProSe: March 2015

R13 eProSe: March 2016

R14/15 FeProSe: Limited work June 2017 / Sept 2018

R13 V2X March 2016 Feasibility study based on ProSe

R14 V2X June 2017

Release 15 5G September 2018

Sept 2016 RAN announces initial spec 

Sept 2017 Qualcomm announces trials (9150)

High power devices allowed for the service

ProSe

V2X

Multi-carrier aggregation/ 64 QAM / power Class 2/ extended sensors

Support for: platooning, advance driving, remote driving

“it was noted that solutions defined for V2X can also be used for public safety when the service requirement can be met.”

Limited market for public safety only features

R16 V2X March 2020

R17 Direct communications: TBD

Higher throughput, sensor sharing, trajectory sharing

‘Direct Comms’ Study on system enhancement for proximity based services in 5GS

Direct services have commercial and public safety elements

V2X interfaces

Source: 3GPP
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 7 TM

Designed to address direct inter-vehicle 

communications

Uses GNSS for synchronization when available

Proposed relay support

Designed for V2X bands; but extensible

Extensive standards development

• Could include PS requirements

Improved congestion control

Lower latency

Improved selective fading performance

Support for rapidly moving vehicles (radios)

Larger capacity with 5G

ProSe versus V2X

Designed to address public safety off 

network requirement

Distributed sync

Network Relay supported

Band agnostic

Limited 3GPP support for separate PS 

std. 

V2X enhancements

Common waveform: PC5
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 8 TM

Communication methods in challenging environments

Buildings

Remote 

Areas

Direct 

Communications

Satellite 

Communications Mobile Base Stations

LTE/5G Network

Network Coverage

No Network Coverage

Urban 

Canyons Geographic 

Canyons

Major 

Emergencies

(infrastructure 

down)

WiFi

First Response

If available; when not effected by emergency Requires deployment
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 9 TM

Isolated worker

Comparable communications range to P25

• Mixed environments

• Inbuilding – high RF losses

• Remote communications - clear line of site – large signal latencies

“In these situations the employed radios need to work under a potentially very 

large path loss, yet still provide prompt delivery of media. Both network mediated 

and direct device to device communications are envisioned.” TS-22.186
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 10 TM

Signal search limitation

Disadvantage

position Advantaged

position

Line of sight propagation – direct communications

3GPP standards work has focused on short ranges

• Synchronization search windows limit range, but save battery 

life

• Default configurations limit range of protocol: e.g. cyclic prefix

• V2X importance is inversely proportional to distance

Public safety uses can be longer range

Communication by advantaged terrestrial location

Communication by UAV (advantaged aerial location)

(relay)

P25 searches for signals continuously; 

range is limited by signal loss
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 11 TM

Apparent physical distance vs. RF propagation 

ProSe/ V2X have range limitations

• Multipath - protocol

• Distance – implementation/ protocol

Search and rescue

multipath limitations 

Apparent physical

distance

Primary

RF path

Propagation distance dilation 
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 12 TM

BLER as a function of synchronization error & multipath

25

20

10

15

5

0 -5

-10

Receiver performance degrades with time offset

§ Standard cyclical prefix

§ ~40 samples per mile

§ Best performance ~ 3/8 mile with EPA5 fading

Mitigation

• Extended multipath tolerance: not supported in V2X

• Continuously scanning receivers: may not be defined by standards

-5 0

5

10 15

25

20
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 13 TM

V2X limitations

Currently no relay support

No discovery

Communications range

• Support for isolated worker

• Advantaged locations

• Aerial vehicles

• Terrestrial

Communication scenario 

description

Req # Payload 

(Bytes)

Tx rate 

(Message 

/Sec)

Max 

end-toend

latency

(ms)

Reliability 

(%)

Data rate 

(Mbps)

Min required 

communication 

Scenario Degree range (meters)

Sensor 

information 

sharing 

between UEs 

supporting V2X 

application

Lower 

degree of 

automation

[R.5.4-001] 1600 10 100 99 1000

Higher 

degree of 

automation

[R.5.4-002] 10 95 25

(NOTE 1)

[R.5.4-003] 3 99.999 50 200

[R.5.4-004] 10 99.99 25 500

[R.5.4-005] 50 99 10 1000

[R.5.4-006]

(NOTE 2) 10 99.99 1000 50

Video sharing 

between UEs 

supporting V2X 

application

Lower 

degree of 

automation

[R.5.4-007] 50 90 10 100

Higher 

degree of 

automation

[R.5.4-008] 10 99.99 700 200

[R.5.4-009] 10 99.99 90 400

NOTE 1: This is peak data rate.

NOTE 2: This is for imminent collision scenario. 3GPP TS 22.186
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 14 TM

Networking bridging relay

Fire fighters in building may use direct comms

Potential relays should:

• Provide automatic operation

• Monitor for relay requests

• Coordinate with other proximate relays

• Multiple relays may be active

• Minimize and mitigate harmful interference

• Maximize relayed coverage

• In-building

• Remote location extension 

R

R

R

R

R

R

R

R

R

R

R

R - Relay capable equipment

R
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 15 TM

Direct communications extension relay

(A)

(B)

relay

(E)

(D)

Obstacle

Obstacle

(C)

Benefits

§ Extended range

§ Reduces obstruction effects

§ Improve delivery reliability

Disadvantages

§ Twice as many radio resources

§ Quasi-static deployment

§ MIMO capabilities not fully utilized
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 16 TM

Cooperative communication (example)

Benefits

§ Higher effective transmitter power

§ Diversity: M x 2

§ Dynamic cooperative communications

§ Improves communication with obstructions 

Challenges

§ Managing congestion with many groups

Obstacle

Obstacle

Cooperative devices: (B,C,& D)

synchronously echo messages

during re-sends

(F)

(G)

(E)

(A)

(D)

(C)

(B)

Application level forwarding or lower level coverage enhancement
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 17 TM

Cooperative support algorithm

Each device acts independently

CSA

(Cooperative

Support

Algorithm)

Configuration

§ System policy

§ Local policy

Priority

• Protocol

• Application

Radio Metrics

§ Signal quality

§ Signal loading

Transmission

Support

Decision

Originating

device

Benefiting

device

Support

devices
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 18 TM

Relative coverage

Basis for coverage comparison between P25 and ProSe

• Represents best case scenario

• Coverage decreases with increasing throughput for data services

P25, 1

HP-UE, 0.1 HP-UE, 0.29

UE, 0.05 UE, 0.11

15

20

25

30

35

40

Effective Radiated Power (dBm)

Relative coverage

Data Voice services

P25 

Portable Portable

HP-UE 

Portable

Nominal Tx Power 35 23 31

MIMO 1x1 1x2 1x2

Rx Effective IF Bandwidth (kHz) 6 360 360

Rx Noise Figure (dB) 6 7 7

Faded Performance Threshold DAQ3.4 

(dB) 17.7 -2.2 -2.2

Maximum RF Coupling Loss (dB) 147.5 136.6 144.6

Antenna Efficiency. (dB) 0 -4 -4

Maximum Link Loss 147.5 128.6 136.6

Radial Coverage Relative 1.00 0.34 0.53

Area Coverage Relative 1.00 0.11 0.29

Internal 

antenna
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 19 TM

Improving direct coverage

Staying within the standards

• High power UE (standardized for band 14 & others)

• High efficiency antennas

§ Integrated antennas generally have much lower efficiencies

• Singular transmission schemes in time (configuration)

§ For example: single service per ProSe period (40 msec.)

§ Counter example: Video, Text, and Voice as separate physical 

packets

• Lower rate voice CODECs

§ For example: P25; maybe required for end to end encryption

§ Or negotiated by a device in limited coverage

Push the standards forward

• Linking PS requirements to other verticals

• Extended coverage range

§ Rural & in-building

VS.
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris | 20 TM

Interim solutions

LMR/ proprietary for direct voice communications

When available ProSe/ V2x for direct services at closer range

Broadband for network communications

Carry direct and broadband devices

Carry device with integrated capabilities

Field qualified broadband direct solution

Direct mode sleeve

Proprietary airlink

Separate devices

Integrated device P25 network/direct

P25 network/direct
Technology to Connect, Inform and Protect Stakeholder Meeting 2019 ProSe Harris 

| 21 TM

dericson@harris.com
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