VoIP over 1xEv-DO Revision ACDG VoIP SummitRobert Kerr – Nortel

Sr. Manager – Access Product EvolutionSan Diego, Feb 8 ‘05

2

Presentation Topics

1. Why VoIP

2. Elements of a successful VoIP offering

3. VoIP capacity over DO Rev A

4. Voice Quality considerations

5. Signaling Analysis

6. Optimizing for VoIP deployment

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Added value of VoIP over 1xEv-DO RevA> VoIP is just one practical application – solving the VoIP

challenge allows support of other revenue generating real time applications/services• Rich Services (gaming, video conferencing, etc.)

> Following the trends from the wireline industry• Ability to offer seamlessly integrated and easy to use real time

data services such as VoIP Strengthens competitive position among wireless operators

> Enables a standalone 1xEv-DO RevA network with both broadband data and voice.• Reduced Complexity in the network by duplication of functions

> Enables a single carrier to support voice & data versus a dedicated voice & dedicated data carrier.

> Simplified Network maintenance, seamless services integration & a richer end user experience

VoIP is a leading practical real time data application Paving the way for other new revenue generating services

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Key Challenges in Commercializing VoIP

> End to End QoS and Policy Enforcement between access and core• Must be able to correlate billing records with QoS and service

authorization

> Network Performance• Capacity • User experience: Call setup times, voice quality • In network vs. out of network performance

> Security Management• Firewall Traversals, Denial of Service attacks, Virus Protection,

VPN Management

> Regulatory Issues• CALEA, E911, WPS, etc…

VoIP over DO 1xEv-DO RevA requires an End-to-End solution extending all the way through the network

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1xEv-DO RevA VoIP Enablers

> Key enablers are low E-2-E network latency and FL/RL capacity

> DORA network enhancements well suited to support VoIP> Forward Link Enhancements

• Improved FL packing efficiency (Short physical layer packets, multi-user packets)

> Reverse Link Enhancements• Increased reverse link throughput / capacity• Support of reverse link hybrid ARQ, Support of sub-frames• Reverse link MAC enhancements to reduce latency• Flow specific MAC layer attributes

> Flow specific attributes / QoS: Scheduler in BTS> Call set up enhancements

Increased capacity and reduced latency supporting VoIPIncreased capacity and reduced latency supporting VoIP

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VoIP requires End-2-End Network analysis

D. Network Latency Identify existing Network nodal bottlenecks, provide latency guidelines for leased or home network resources

E. Handoffs Analyze / document required handoff mechanisms

F. Core interactions Billing considerations Security (Net. Addr. translation, Firewall traversal)

G. Quality of ServiceDefine E-2-E network QoS flow, QoS negotiation mechanisms

Nortel Analysis A. VoIP Capacity

End-2-End capacity analysis Packet Data network capacity, congestion, bottlenecks analysis

B. VoIP QualityAssess impact on VoIP Voice quality Recommend optimizations, acceptable tradeoffs

C. Signaling assessmentMessaging obstacles (# mess., length)Standards based optimization Call set up delay too long

Nortel has completed VoIP analysis and is focusing on required standards based optimizations

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Overall Capacity Summary 2% per-user outage in FL, No PPP overhead

VoIP capacity is Reverse link limited – Projected capacity of ~40 Users per Carrier-sector

50-6030-3520-2510-15

110110110110 30303030Airlink delay (ms)

10-20~ 10< 10< 10Capacity

YesNoYesNo1/8-rate frame blanking

Dual receive antennaSingle receive antenna

50-6030-3520-2510-15

110110110110 30303030Airlink delay (ms)

10-20~ 10< 10< 10Capacity

YesNoYesNo1/8-rate frame blanking

Dual receive antennaSingle receive antenna

FL (Land-to-Mobile)

RL (Mobile-to-Land)

38

60

Yes

30

60

No

12-Slot Termination

90904040Airlink delay (ms)

39322921Capacity

YesNoYesNo1/8-rate frame blanking

16-Slot Termination8-slot Termination

38

60

Yes

30

60

No

12-Slot Termination

90904040Airlink delay (ms)

39322921Capacity

YesNoYesNo1/8-rate frame blanking

16-Slot Termination8-slot Termination

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Call Quality / Delay Analysis

> Delay is not only parameter to consider in Voice quality analysis

> ITU-T G.107 incrementally looks at MOS score to understand user experience

Voice quality impact of delayDO to landline

DO-DO calls: In a closed DO network

DO to 1x: Requires TrFO* to mitigate delay. 2 wireless links + vocoding

optimize delay

Need to optimize delay

Acceptable

Network delay ranges from “acceptable” to “Needs optimization”for the various call models. Delay critical to voice quality

DO toLand

DO toDO

DO to1x

DO to1X trfo*

Mobile call model

DO Rev A1xRTT

74 76

5963

5561

4045

5055

60

6570

75

80

DO toLand

1x toLand

DO to DO 1x to 1x DO to 1xwithout

TrFO

DO to 1xwith TrFO

-4

0

11

Del

ay

Tolerable delay threshold

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Signaling Assessment Overview> The assessment examines the call setup delays that can be

anticipated for VoIP calls in a 1xEv-DO Rev A based Multimedia Domain (MMD) network.

> Our analysis is focused on 3 particular end to end call types1. AT Handset to AT handset (i.e. Mobile to Mobile)

• AT implies DORA handset with a VoIP client2. AT Handset to Landline (PSTN)3. At Handset to 1xRTT phone (inter-technology Mobile to Mobile scenario)

> Two 1xRTT based call types are included for comparative purposes.

1. 1xRTT MS to 1xRTT MS (i.e. Mobile to Mobile)2. 1xRTT MS to Landline (PSTN)

> In looking at call setup delays, the focus is on the time from the caller pressing “Send” to the caller hearing ring-back. This ringing provides assurance that the call is working and effectively restarts their mental timer.

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I-CSCF

Visited2Home2Home1Visited1Message Flow example – AT to AT

UserBPDSNPDSN

+ RNBTSDOM RN+

BTSDOMHA

Route Update (ACH)AC Ack (CC)

Connection Request (ACH)

Traffic Channel Assignment (CC)

Traffic Channel Complete (RTC)RTC Ack (FTC)

Pilot + DRC (RTC)

ASHSS

P-CSCF S-CSCF I-CSCFS-CSCF

P-CSCF

TCP:SYNC – (port 5060)

HA

(A)Dormant

ToActive

TCP:SYNC – (port 5060)TCP:SYNC+ACK – (port 5060)TCP:ACK – (port 5060)

TCP**Connection 1

SIPINVITE

TCP**Connection 2

TCP:SYNC+ACK – (port 5060)TCP:ACK – (port 5060)

TCP:SYNC – (port 5060)

SIP INVITE(Cont’d)

Traffic Channel Assignment (CC)

RTC Ack (FTC)Pilot + DRC (RTC)

Traffic Channel Complete (RTC)

(B)D to A

TCP**Connection 2

(Cont’d)

*

Preconditions: Both User A and User B terminals have been powered on, and have registered with the DO & Packet Data Core Networks and the SIP Server. Neither terminal has an RF link at the time of the call.

UserA

* For clarity, reverse direction “100 Trying” messages, in response to “Invites”, are not shown.** TCP signaling shown. If UDP is chosen, there is no equivalent UDP messaging.

verification of session ownership

I-CSCF gets S-CSCF from HSS(2)

AS access for “A”would occur here if included in timings.

S-CSCF determines correct Home2 I-

CSCF from HSS(1)

If UDP is used, the SIP Invite reaching the RNC triggers the

Traffic Channel setup.**The Invite then proceeds to the AT.

AC Ack (CC)Route Update (ACH)

Page

AS access for “B”would occur here if included in timings.

Example of extensive invite

messaging from terminal

A to terminal B

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I-CSCF

SIP 200 OK(to INVITE)

SIP ACK

Message Flow - AT to AT - continuedUser

AUser

BPDSNPDSN+ RN

BTSDOM RN+

BTSDOMHA

ASHSS

P-CSCF S-CSCF I-CSCFS-CSCF

P-CSCF HA

SIP 180Ringing

SIP PRACK

Example: Messaging leads to 8.5 sec call set up delay

SIP 183

SIP UPDATE

SIP PRACK

SIP 200 OK

SIP 200 OK

SIP 200 OK

Authorize QoSResources

Authorize QoSResources

UE Resource Reservation

Visited2Home2Home1Visited1

Ring-back

Alerting

UE Resource Reservation. Messaging between UE and P-CSCF.

Answer

Media FlowMedia FlowP-CSCF enables

Media flow at PDSN.

P-CSCF enables Media flow at PDSN.

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Example Result for Post Dial Delay

5.4

8.0

4.23.7

2.5

0.4

0.5

0.20.3

0.1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

AT to 1x AT to AT AT to Land 1x to 1x 1x to Land

Call Types

Sec

onds

(PAD) Post Answer Delay

(PDD) Post Dial Delay

Local/National IPv4/v6 TCP/UDP ROHC SIP CompressionNational 4 UDP Yes Yes

Target ITU PDD for

National call.

Targeted interval

Industry Benchmark 1x CS voice

today

5.4

8.0

4.23.7

2.5

0.4

0.5

0.20.3

0.1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

AT to 1x AT to AT AT to Land 1x to 1x 1x to Land

Call Types

Sec

onds

(PAD) Post Answer Delay

(PDD) Post Dial Delay

Local/National IPv4/v6 TCP/UDP ROHC SIP CompressionNational 4 UDP Yes Yes

Target ITU PDD for

National call.

Targeted interval

Targeted interval

Industry Benchmark 1x CS voice

today

Industry Benchmark 1x CS voice

today

Post Dial delay currently excessive due to signaling

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Contributions to Post Dial Delay> In most cases, transport of the SIP messages over the air link

is the single largest contributor to PDD.

Local / NationalNationalIPv4/v6

4TCP/UDP

UDPROHC

YesSIP Compression

Yes

Post Dial Delay Breakdown

0.71.6

0.7

2.0

3.9

2.0

2.7

2.5

1.6

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

AT to 1x AT to AT AT to LandCall Type

Sec

onds

Core Network

Signaling over RF Link

Traffic Channel Setup

ITU reference

Target

Post Dial delay optimization opportunities are understood and being worked for future standards contributions

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MMD based Signaling assessment Conclusions

> Post dial delays for VoIP calls using SIP based signaling are projected to be from 3 to 6.5 seconds longer than the accepted targets

> Expected call set up target of 3 seconds increases required optimization to between 5 and 8.5 seconds

> The actual call set up delay will vary depending on the call type and network assumptions.

> Of the AT originated call types, no network options achieved PDD targets for VoIP over DOrA calls with the exception of AT to Land calls.

> Nortel is making good progress internally on proposals to optimize the signaling and reduce the signaling delay.

Optimization of signaling should target maximum optimization while preserving SIP extensibility. How Signaling is

optimized/implemented has yet to be resolved.

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Conclusions> Nortel VoIP Capacity simulations demonstrate VoIP over 1xEv-DO

RevA can provide 1X or greater capacity, and continued industryfocus is justified.

> Voice quality is challenged by network delay• Additional bearer path delay optimization would further enhance Voice Quality,

specifically for DO to 1x and DO to DO call models.

• Nortel has identified Key areas for delay improvement

> Signaling analysis: Problem areas requiring industry effort to resolve• Post dial delays for VoIP calls using MMD SIP based signaling are projected

to be from 0.1 to 8 seconds longer than the accepted targets

• None of the call types (e.g. AT to AT, AT to Land) or network options (e.g. IPv4 vs. IPv6) achieved Post Dial Delay targets for VoIP over DO RevA calls.

• Nortel is committed to defining Standards changes, or additions to the MMD SIP signaling architecture to support VoIP over DO RevA using an MMD architecture

VoIP over DO Rev A is a valid evolution path, meriting further industry focus to support over 1xEv-DO RevA

Thank you