istanbul, 01.-03. april.2014gsm-r packet switched technology ingo wendler / uic project manager -...

Istanbul, 01.-03. April.2014GSM-R Packet Switched TechnologyIngo Wendler / UIC Project Manager - ETCS over GPRS

GSM-R Packet Switched Technology

Introduction of GPRS/EGPRS for ETCS


France Germany

Switzerland

High Density Area-Border Region

(1) Packet Mode for ETCS Motivation

Status GSM-R Air-Interface CapacityETCS data application widely used in low density areas (track)What about high density areas like stations?

Voice capacity demand increases! ETCS in stations demands additional

Circuit Mode channels! Border regions have to share the

limited number of frequencies Capacity demand conflicts with the limited GSM-R(EIRENE) frequency band resources Increase radio channel multiplexing – keep QoS requirements transition towards packet switched modeCircuit Mode-

Dedicated ChannelPacket Mode- Shared

Channel

Track High Density AreaStations


(2) GSM-R ETCS Bearer Circuit Switched (CS) versus Packet Switched

Circuit Mode (CS-Mode) Dedicated transmission resource per

ETCS session Sufficient transmission robustness

(Radio Network design) Low traffic channel capacity utilisation (10-

20%)

Packet Mode (PS-Mode GPRS/EDGE) Shared transmission resource(s) between

several ETCS sessions Bearer Service bandwidth depends on:

Channel Coding (more/less robust against transmission errors caused by Doppler and Delay spread)

Radio Network design

Improved protection algorithms against transmission errors

Multiplexing of several ETCS sessions improves resource utilisation

PS ETCSPS ETCS

PS ETCS

PS ETCS

CS ETCS

CS ETCS

CS ETCS

CS ETCS


(3) GSM-R ETCS Bearer Circuit (CS) versus Packet Switched (PS) Mode

CS-Mode Resource

PS-Mode Resource

Demand

Release

Demand

Release ETCS - «LOW» Delay

Other «Best Effort»Applications


(4) GSM-R GPRS/EDGETest Cases(O-3023v0.73)

User Area - ETCS traffic emulationTraffic Model 1 - Limit•Reflects high radio traffic channel utilisation•Message frequency

every 3 seconds Train RBC every 6 seconds RBC Train

Traffic Model 2 - Typical•Reflects medium traffic channel utilisation•Message frequency

every 6 seconds Train RBC every 20 seconds RBC Train

Mixed Traffic – Application dependent bandwidth allocation•Traffic Model 1/2 + non-ETCS data Network Registration

Boundary Test Conditions

Var

iatio

n of

Ch

ann

el

Co

din

g

(GP

RS

/ED

GE

)

Var

iatio

n of

Rad

io T

raff

ic

Ch

ann

el

qua

ntity

Var

iatio

n in

ET

CS

Se

ssio

n

qua

ntity

sh

arin

g on

e R

adio

T

raff

ic C

han

nel

Variation of Radio Channel Conditions (Optimum 320km/h)

GSM System3GPP Features to improve PS-Mode: •Radio Resources Allocation respecting ETCS application•Mobility behaviour (Cell Change)•Ensure ETCS application precedence over non-ETCS traffic

Specific Test Conditions

Test Case Focus

GSM Feature Gain

Multiplexing Gain of one Radio Traffic Channel

GPRS/EDGE robustness

CS-Mode and GPRS/EDGE co-existence

IP-performance for transport layer parameterization


Track (Ø 50km/h up to 320km/h

LAB Phase 2(Optimum Radio)

LAB Phase 1(Optimum Radio)

(5) GPRS/EDGE Bearer Optimisation - Testing Procedure

Measurement Tool

GSMFeature Activation

Performance Reference “Best Effort”

Feature GainIP-Performance

Final-LABParameter Timer

RobustnessParameter Timer

GSMFeatureQualification

Radio AccessTechnology Independent

Timestampgeneration

Transfer Delay Computation

Traffic ModelEmulation

Control of min. 4 concurrent Mobile Modules

Reporting

FinishedFinished

Mixed Traffic (ETCS/Non-ETCS)

Automated Cell Change

ETCS Traffic Model •Traffic Model 1 •Traffic Model 2

Tool Qualification


(6) GSM-R GPRS/EDGE Results: Feature Gain

PS-Mode Resource

Demand

Release ETCS - «LOW» Delay

Other «Best Effort»Applications


(7) GPRS/EDGE - ETCS Bearer Results:

• 4 concurrent ETCS sessions @320km/h• 6 concurrent ETCS sessions under static conditions

Mu

ltip

lexi

ng

Gai

no

ne

GS

M-R

T

raff

ic C

ha

nn

el

Imp

act

Cir

cuit

P

acke

t M

od

e

• Co-existence guaranteed- matter of GSM-R capacity planning• Requires min. one dedicated Packet Mode Traffic Channel

• 3GPP GSM features improves transfer delay significantly• (TTD) equal/better than Circuit Mode for ETCS • Recovery of erroneous packets faster than in Circuit Mode

Tra

ns

mis

sio

n

Tra

ns

fer

Del

ay

/R

ob

ust

nes

s

CS ETCS

PS ETCS PS-Mode

CS-Mode

PS ETCS

PS ETCS

PS ETCS

PS ETCS


• Operation of the required features• Planning recommendation (Min. Packet Switched capacity, Channel Coding)

(8) GPRS/EDGE - ETCS BearerRelated Documents

0

200

400

140

200

260

350

500

560

620

680

740

800

860

950

1200

1800

• Transport Channel qualification Transfer Delay (Transmission Interference – Transport Protocol impact)• Multiplexing Gain –New!

Su

bs

et09

3B

eare

r S

erv

ice

Qo

SP

S-M

od

eE

ng

inee

rin

g

• 3GPP GSM feature specification MRM/Network• PS-Mode functions• Full Qualified Domain Name(s) RBC / OBU Identification• IP Addressing SchemeE

IRE

NE

SR

S/F

RS

GPRS CS2 EGPRS MCS2 GPRS CS2 EGPRS MCS2subset093 95%subset093 99%

Requirements

1 Traffic Channel 2 Traffic ChannelTransfer Delay


(9) GPRS/EDGE - ETCS Bearer Conclusion(s)

Transformation Best Effort “QoS Transmission System ”

3GPP Features Standard features are sufficientto fulfil application QoS requirements

Robustness Faster detection and retransmissionof erroneous radio blocks with less impactto higher layers

PS-Mode (GPRS/EDGE) providesa capacity improvement especially in high density - railway traffic areas!

Radio Access Technology Independent Measurement ToolETCS / non-ETCS Traffic EmulationTransport Channel – System Qualification (i.e. Transfer Delay/Multiplexing Gain)