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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
3 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
Voice over IP Drivers
Cost SavingsCost Savings
Coverage Expansion for WirelessCoverage Expansion for Wireless
Rich Communication ServicesRich Communication Services
4 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
5 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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).
6 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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
7 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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
8 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 Las Vegas
MMD (Multimedia Domain) IMS (IP Multimedia Subsystem)
9 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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…)
11 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
12 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
13 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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).
14 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 Las Vegas
Header Compression:Data path and Signaling path compression techniques
15 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
16 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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
17 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
18 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 Las Vegas
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.
19 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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
20 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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
21 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
•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
22 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.
23 © NOKIA 2004 CDG Technology Forum on VoIP November 4, 2004 – Las Vegas
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.