2_lienhart_presentation_hspa_performance_fh_osnabr_ck-30-05-2007.pdf

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1 Nokia Siemens Networks Performance of VoIP and Mixed Traffic over HSPA / Johann Lienhart / 30.05.2007

For internal use

Performance of VoIP and Mixed Trafficover HSPAJohann Lienhart, Siemens AG, Vienna, AustriaMnir Askar, Martin Kuipers, Nokia Siemens Networks GmbH&Co. KG, Berlin,Germany


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Overview

Motivation for VoIP over HSPA investigations

Dynamic System Level Simulation

Simulation Strategy HSPA Parameters

VoIP over HSDPA in Downlink

QoS, Scheduling Algorithm Results for VoIP and mixed traffic over HSDPA

VoIP over E-DCH in Uplink

QoS, Scheduling Algorithm Results for mixed traffic over E-DCH

Conclusions


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HSPAdesigned for efficient transport of

traditional data traffic due to

AMC Fast Scheduling

HARQ

interesting whether efficiency is alsoachievable for VoIP small packet sizes

delay requirements

Motivation for VoIP over HSPA investigations

VoIPVoice over Internet Protocol (VoIP) is

a technology allowing the routing ofvoice conversations over the Internetor any IP packet-switched network

VoIP over cellular network stands forthe support of VoIP packets over anymobile infrastructure based on thePacket Switched (PS) domain

expected to become increasingimportance for future mobile networkgenerations

Investigation of VoIP over HSPA feasibility andperformance

under Rel-5/6 constraints


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Dynamic System Level Simulation - Simulation

Strategy MoRSE Mobile Radio

Simulation Environment

Fully dynamic simulation with57 cells mobility, handover, etc.

12 inner cells are referencecells

Real interference from interfererrings

Control channels (Rel5 & Rel6)with power control and soft

handover Session based traffic model and

satisfied user criterion

QoS based dropping

Link Level-Performance:Actual Value Interface implemented

Site/Node B

Reference Area

UE


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VoIP over HSPA - Simulation Parameter

HSPASite to site distance 1.5 km, PL according UMTS 30.03

Fast-fading models (PedA 3 km/h)

Max Node B power 43 dBmMax UE power 21 dBm

TTI 2ms for HSDPA and E-DCH

HS-PDSCH just HHO; E-DPDCH also SHO

HSDPA Rel5 and E-DCH Rel6 features

VoIPROHC with initial full header, partly and fully compressed header

VoIP payload 31 byte per 20 ms, SID frames 6 byte per 160 msPacket discarding according to delay budget


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VoIP over HSDPA Scheduler Principle VoIP User

VoIPPFSYes

FIFO(RR)No

YesNo

Delay-aware

Link-

adaptive

h = channel stateT = throughput

HOL = waiting time of first packet in queue

PFS metric: SM = T(h) / T

FIFO metric: SM = HOL

VoIP metric: SM = w(HOL) * h2/h2

VoIP metric weight function

0

1

2

3

4

0 20 40 60 80 100 120

weighting time HOL

weightvaluew

80ms

120ms

some implicitdelay awarenessin forgetting factor

Packet aggregationsmall weight value in initial 40ms

Link adaptation

constant weight value 1

until final 30ms

Delay awareness

fast increasing weight value,when approaching delay threshold


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VoIP over HSDPA Results for VoIP only traffic

VoIP Performance, Ped A, 3km/h, 2% packet loss rate

55

60

65

70

75

80

85

90

95

100

40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115

VoIP Users per Cell [-]

RSU[%]

VoIP, 80ms

VoIP, 120ms

FIFO, 80ms

FIFO, 120ms

PFS, 80ms

PFS, 120ms

71

83

102

64

72

83

47

56

0

10

20

30

40

50

60

70

80

90

100

110

60ms 80ms 120ms

VoIPUserspercell

VoIP

FIFO

PFS

Capacity:Number of users inref. cells when 95% of users aresatisfied

delay aware

link adaptive

delay aware

PFS FIFO VoIP

link adaptive

VoIP user is satisfied if:

user is not droppedor blocked

not more than 2% ofpackets are lost ordiscarded


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In real systems VoIP users have toshare radio capacity with other userstherefore VoIP user and web trafficuser are served within the samescenario

Optimized scheduling and properprioritization of services will be crucialto maintain the radio capacity

100% VoIP load is taken as referencevalue (PedA3 channel, VoIP specific

scheduler with 80ms delay budget) Several VoIP load levels are kept

constant (82%, 47% and 24%) in ascenario

Web user load is stepwise increased

The overall capacity of the system isdetermined if the threshold is reachedwhere both user groups are justsatisfied

VoIP over HSDPA Mixed service simulation

VoIP load level

83

67

39

20

0

10

20

3040

50

60

70

80

90

100 82 47 24

Percentage of pure VoIP capacity

VoIPUserpercell


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WWW and VoIP Users arescheduled in a single step butdifferent metric weight functionsare used - special scheduler metriccalculation for data user

SM of data is intended to bedirectly comparable with VoIP SM

Throughput aware component aswell as channel conditioncomponent

w is a general screw to weight theentire data SM

w(r) increases if the averagethroughput falls below a threshold(rmin) and decreases if throughputbecomes higher than the threshold

VoIP over HSDPA Scheduler Principle data user

kbpsr 64min =

2

2

)(

h

hrwwSM Data =

r

rrw

min)( =

1=w

general weight:

datarate dependend weight:


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Traffic Model HTTP traffic proposal follows widely web

traffic model of TS 25.848

Session consists of 10 packet calls

(representing web page download) Pareto distributed packet call sizeMean size 25kbyte(UL mean size 5kbyte)

Geometric distributed reading timemean: 5 sec

t

packet service session(10 packet calls)

Packet call

reading time

VoIP over HSDPA Traffic model for Data user &

QoS QoS Mean user throughput of each session is

collected/drawn in a CDF

Capacity of scenario is reached if at most

5% of the sessions have a average userthroughput


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Overall capacity if both user groups are satisfied

Web traffic users will be earlier unsatisfied as VoIP user Only RSU of web traffic users are determining the overall capacity Very high VoIP load dont allow any satisfied web user

VoIP over HSDPA Mixed service simulationResults

0 0

12

26

33

0

5

10

15

20

25

30

35

VoIP 100% VoIP 84% VoIP 47% VoIP 24% VoIP 0%

Percentage of pure VoIP capacity

WWWU

serpercell


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VoIP traffic

276 bit VoIP payload (incl. RoHC) every 20ms+ 16 bit RLC header + 18 bit MAC Header

VoIP packet fits into TBS of E-TFC 1 (354 bit)

Scheduling type

VoIP traffic is transported in unscheduled mode (signaling overhead reduced).

UE doesnt care about grants since in principle only one TBS is necessary.every UE can send as soon as VoIP data is available

VoIP over E-DCH Scheduling Principle VoIP

26460666

26433775

22220344

224102632246902

2143541

TTI [ms]No. CodesSFTBS [bits]E-TFC


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VoIP user transmits in unscheduled mode.Remaining UL capacity is scheduled for datausers.

NodeB scheduler:RTWP (received at NodeB) is managed.NodeB scheduler grants resources to UEbased on the estimated available E-DCHpower and RTWP.Users are ranked according fair throughput

metric.Available E-DCH power depends on inter/intracell interference and on the RTWP target.

UE selection procedure:UE selects E-TFC which fits to the granted

resource.Max. UE TX power and buffer fill level is alsotaken into account.

P(noise)

I(oc)

P(1)

P(2)

P(n)

P(E-DCH_data)

RTWP target

Available power for E-DCH

Power used for any otherphysical channelse.g. E-DCH VoIP user

Other cells interference

Thermal noise

UL Interference Management:

VoIP over E-DCH Scheduling Principle Data


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VoIP over E-DCH QoS Satisfied User Criterion

Final capacity is the minimum of RSU & NR capacity

WWW satisfied user criterion

the same like for DL butdifferent throughput threshold

32kbps instead of 64kbps

WWW scenario capacity (RSU)

Capacity of scenario isreached if at most 5% of the

sessions have an average userthroughput below 32kbps

VoIP satisfied user criterion

the same like for DL

VoIP scenario capacity (RSU):

Capacity of the scenario is reachedif at least 95% of the speech usersare satisfied

RSU capacity

additional aspect in UL compared to DL

Radio network capacity is reached if 95th percentile of Noise Rise at theNodeB exceeds 6 dB.

Noise Rise capacity


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All mix combinations below curve can be served

E-DCH: Smooth characteristics of the capacity region

HSDPA: Non ideal at high share of VoIP users

VoIP over HSPA Mixed service simulationCapacity RegionPercentage of VoIP user load over percentage of web user load

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100

Perc. of VoIP capacity [%]

Perc.

ofhttpcapacity[%]

HSDPA

EDCH


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Delay-aware and Link-adaptive scheduling metric performsbest

VoIP specific scheduler causes packet aggregation whichleads to higher capacity

Principally possible to schedule different user groups withHSDPA

No general capacity breakdown at mixed traffic

Exception at high VoIP load levels, where no web user can bescheduled

The transmit power is not the limiting resource in the mixed scenario

The amount of possibly scheduled user per TTI is one of the limitingfactors

VoIP over HSDPA Conclusions


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VoIP over E-DCH Conclusions

Principally possible to serve unscheduled VoIP user grouptogether with scheduled web user group

Regarding RSU criterion, web user satisfaction is the limitingfactor in mix scenarios (VoIP User are preferred due tounscheduled mode)

VoIP users always satisfied as long as the Data scheduler

suceeds in Noise Rise restriction UL VoIP capacity limited by Noise Rise


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Thanks a lot for your attention

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