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1 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 Las Vegas

Enablers for VoIP in CDMA

Poornima LalwaneyTechnology [email protected]: +1 858 831 4727

2 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas

Outline

• VoIP introduction• Enabler components

• MMD (Multimedia Domain)/IMS(IP Multimedia Subsystem)• Codecs (VMR-WB)• Header Compression• Mobility management

• Summary


Voice over IP Drivers

Cost SavingsCost Savings

Coverage Expansion for WirelessCoverage Expansion for Wireless

Rich Communication ServicesRich Communication Services


VoIP over CDMA - Requirements

• CDMA leads other cellular technologies in the intent to deploy VoIP (while trailing cable and WLAN VoIP deployments).

• The following points should be addressed to ensure mass VoIP uptake in CDMA

• Interoperability with fixed line VoIP (cable, DSL, enterprise and consumer WLAN) and other cellular (3GPP) VoIP deployments.

• CDMA and other cellular technologies need to address mobility management for the VoIP session.

• Enhancing the CDMA system to provide VoIP service on-par with current circuit switched voice presents new technology challenges from physical layer to applications layer.


VoIP Protocols

SIP is an IETF application layer protocol for establishing, manipulating, and tearing down sessions. Through session registration and management, it provides a framework to develop new services.

Consumer IP TelephonyEnterprise IP Telephony

SIP

Media Gateway Control Protocol is an IETF protocol used on cableaccess for VoIP. Cable VoIP core uses SIP.

Cable Consumer IP Telephony

Megaco (MGCP)

DescriptionDeployment Signaling Protocol

Enterprise IP Telephony H.323 is an ITU standard for video conferencing in fixed enterprise. Initially designed for use on ISDN networks.

H.323

DescriptionDeployment Bearer Protocol

All above signaling use RTP for the bearer

Real time protocol defines a framework in which codec specific RTP payload formats are inserted. Both RTP base protocol and codec payload formats standardized at the IETF.

RTP

• Signaling protocols will converge to SIP (Session Initiation Protocol).


Common VoIP Connectivity Layer

NG Border Elements

NG Border Elements SIP Border

ElementsSIP Border Elements

H.323Border

Elements

H.323Border

Elements

MGCP Border

Elements

MGCP Border

Elements

H.323 endpoints

SIP endpoints

MGCP endpoints

PSTNLocal, International

Application ServersApplication Servers

Call Control Element

VoIP Functional Architecture

SIP

Fixed Enterprise Cable/DSLWLAN, 3GPP, 3GPP2

CALEA Server

E911 ServerMedia Gateway

SIPSIP

Service CreationService CreationEnvironmentEnvironment

SIP

SIP

Access Layer

Applications Layer

Common network functions: admission control, network routing engine


Nokia’s VoIP component leadership

•Over CDMA2000•Over 1xEV-DV and 1xEV-DO Rev A

•Over WLAN

Header Compression VMR-WB

IPv6/Mobile IPv6 Seamless Handoffs

MMD/IMS Research and standards(3GPP2, IETF, OMA)

VoIP ties together key Nokia technology initiatives


MMD (Multimedia Domain) IMS (IP Multimedia Subsystem)


Standards based IMS (IP Multimedia subsystem)/ MMD (Multimedia Domain)• The IMS provides an industry-wide opportunity to achieve services

convergence using Session Initiation Protocol (SIP)• Single, standardized subsystem that supports services across multiple

terminals & network technologies • MMD Rev A (to be published 1H2005) provides support for VoIP in

CDMA.The IP Multimedia Subsystem (IMS) provides centralized registration, session control and charging mechanisms for operators and application developers.

IMS Supports Multiple Packet Core Networks

(CDMA2000 1X, WLAN,GPRS…)

SIP

SIP

SIP

IP Connection

Game data

Streaming

video

IP

…

IMS Supports Multiple Radio Access Networks(CDMA2000 1X, 1xEV-DO, 1xEV-DV, WLAN,

GSM, WCDMA…)


VMR-WB codec


Overview of VMR-WB Standard

• VMR-WB is the first 3GPP2 standard wideband speech codec that enables both multimode wideband and narrowband voice services in the same package.

• VMR-WB supports both continuous and discontinuous transmissions.

• VMR-WB is fully compliant with CDMA2000 system requirements in all modes of operation.

• VMR-WB Rate-Set 1 mode 4, that has been recently developed and is being standardized, is fully compliantwith cdma2000 system requirements in Rate-Set I, with no capacity impact as compared to EVRC.

• VMR-WB is the first 3GPP2 wideband speech codec and is interoperable with 3GPP/AMR-WB.


Advantages of VMR-WB Standard for VoIP

• Robust performance

• DTX/Discontinuous mode ideally suited to Internet applications.

• VoIP interoperability with AMR-WB through IETF based RTP payload format for VMR-WB.

• Transcoder-Free MMS and VoIP interoperable interconnectionswith 3GPP network with no media format conversion

• Lower end-to-end delay by eliminating transcoding.• Improving quality of service by avoiding quality degradation due to

transcoding• Reducing the complexity and cost of the gateways

• Multiple revenue-generating applications including MMS, voice recording, audio streaming, VoIP, and in conjunction with video for high-end users.


VMR-WB 3GPP2 Standards and Dependencies

• VMR-WB Specification: 3GPP2 C.S0052-0 v1.0 (Service Option 62) published in July 2004

• VMR-WB MPS: 3GPP2 C.S0053-0 v1.0 (Service Option 62) to be published in September 2004.

• VMR-WB Rate-Set I Extension: 3GPP2 C.S0052-A v1.0 (Service Options 62 and 63) to be published in April 2005.

• VMR-WB Rate-Set I Extension MPS: 3GPP2 C.S0053-A v1.0 (Service Options 62 and 63) to be published in May 2005.

• VMR-WB is the default wideband speech codec in 3GPP2 C.S0046-0 and proposed as the default wideband speech codec and optional narrowband speech codec in 3GPP2 C.S0045-A.

• VMR-WB support in “.3g2” and “.cmf” file formats has been approved for the next release of C.S0050-A (file formats).


Header Compression:Data path and Signaling path compression techniques


ROHC RTP Compression (RFC3095)(compress IP/UDP/RTP headers to 1 byte)

• Most of the IP/UDP/RTP header fields can easily be compressed away since they never or seldom change or can be inferred.

• In cellular terminals, the main RTP header field that need to becommunicated between the compressor and decompressor is the Sequence number.

• ROHC RTP compression • Establish header compressor-decompressor context • Reliably send sequence number only on successive packets

• The sequence number can be encoded so that only few least significant bits are sent.

• Could be used over any packet based transport ( e.g. in CDMA: SO33, HRPD) and other wireless (e.g. WLAN) and wireline networks.


Comparison of CDMA2000 1X Header Compression Schemes (both 0-byte)

SO61(LLASO61(LLA--ROHC) ROHC) Pros:Pros:

•Based on IETF HC scheme: LLA-ROHC which compresses the 1 byte to 0-byte.

•Provides synchronization of voice and video streaming based on RTP timestamp

Cons:Cons:•Implementation complexity of Header de/compressor in MS.

SO60 (Header Removal)SO60 (Header Removal)Pros:Pros:

•• Easier to implement compared to SO61 as it uses the synchronous nature of CDMA to transmit only voice samples..

Cons:Cons:•Can not be used for non-voice IP application (RTP header is needed for synchronization)

• SO60 and SO61 limited to circuit switched channel

• SO61 preferred as it preserves timestamps for synchronization


SIP Compression

• SIP based VoIP call setup requires several roundtrips of SIP signaling.

• This can take several seconds (>5 sec) in CDMA.• Compressing the SIP signaling is absolutely essential to

minimize this initial delay.• IETF based Signaling compression (Sigcomp) should used

for ASCII protocols like SIP.• Mandatory to implement but optional to use, in both 3GPP

and 3GPP2 IMS.

• Use Sigcomp with VoIP to avoid creating vendor specific signaling compression – one of the factors that has lead to PTT fragmentation in CDMA.


Mobility ManagementFast handoffs and Context Transfer -Mobile IPv4 and Mobile IPv6

Current CDMA networks manage inter-PDSN mobility using MobileIPv4Voice over IP service requires always-on, global reachability.MobileIPv6 provides better mobility management as compared to MobileIPv4. IPv6/Mobile IPv6 very relevant technologies to be used with Voice over IP as

they may have similar timeframes for mass deployment.


Smooth/Fast/Seamless Handoff• Smooth handoff== low loss• Fast handoff == low delay• Seamless handoff == smooth and fast

Internet

Router-1

Router-2

AccessNetwork

AccessNetwork

Rich Media (Video, Audio)

• Learn New Router Information• Authorize traffic redirection

New route establishment

Announce attachment


Seamless Handoff Protocols

• Fast Handoffs allows a Mobile Node to circumvent latencies due to • IP address configuration change and • location update • Mobile IP handoff delay

• Context Transfer • avoids the need to re-create context (such as header compression,

QoS) on the network• allows smooth operation of applications

• Together, Fast Handoffs and Context Transfers provide the necessary support for seamless user experience

• This is critical for voice applications to eliminate jitter and delay


•IPv4 only: many seconds, have to tear down/rebuild with new IP address

•Mobile IPv4 only, tuned best case scenario: 650ms

•Mobile IPv6,FHOv6: 75ms

•Mobile IPv4,FHOv4: 80ms

Handoff latency

0200400600800

1000120014001600

IPv4 MIPv4 FHOv6 FHOv4

mse

c

Fast handoffs and context transfers are absolutely essential for VoIP


P-P Interface handoffs: Fast Handoff and Context transfer alternative for CDMA

Data from/to CN PPP tunneled over GRE

•Establish P-P interface between the serving PDSN and target PDSN for each R-P connection

•During handoffs, serving PDSN bi-casts the data traffic

Serving PDSN

Target PDSN

Serving PCF

P-P

Target PCF

R-P(A10/A11)

R-P(A10/A11)

Bicasting

•P-P interface handoffs optimized for CDMA; cannot handoff to other access technologies for which MobileIPv4/v6 fast handoffs are required.


Summary

• Interoperability at many levels (Protocols, Codecs, header compression, mobility management) required to make VoIP service successful in CDMA.

• Summarizing the enabler technologies presented• Recommend adopting MMD Rev A for VoIP.• VMR-WB robustness, quality and support for DTX mode

makes it ideal for VoIP.• Recommend ROHC/LLA-ROHC based HC schemes for

packet data services.• Sigcomp essential for end to end signaling compression.• Mobility management ( IPv4 and IPv6 based) should be

used for seamless handoffs across access routers.


Thanks!

Questions?

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