delivering video services over 3g-324m mobile networks

CONTENTS EXECUTIVESUMMARY............................................2

THENEEDFOR3G-324MVIDEOIN3GMOBILENETWORKS........................................2

THE3G-324MPROTOCOLANDSTANDARDS....................................................3

3GMOBILENETWORKINTEGRATIONWITHIPSERVICESCORE.........................................3

ADDINGCONVERSATIONALVIDEOSERVICESTOA3GMOBILENETWORKINFRASTRUCTURE...............5

ELIMINATINGTHE3G-324MVIDEOMEDIAGATEWAY....................................................6

GETTINGREADYFORMOBILEVIDEO.........................7

CONSOLIDATIONLOWERSMOBILENETWORKCOST......................................................7

REFERENCES.........................................................8

DELIVERINGVIDEOSERVICESOVER3G-324MMOBILENETWORKS

HOWANINTEGRATEDMOBILEMEDIASERVERIMPROVESTHEECONOMICSFOR3G-324MMOBILEVIDEOSERVICES

VERSION 1.0 | jaNuaRy 2010

RADISYSWHITEPAPER|DELIVERINGVIDEOSERVICESOVER3G-324MMOBILENETWORKS

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EXECUTIVESUMMARY“Can you hear–and see–me now?” Many mobile phone users want to see the person at the

other end, whether it’s a friend celebrating a birthday, a grandchild saying hello or a healthcare specialist providing treatment. Like many traditional audio-only conversational services, mobile telephony is getting a facelift with the incorporation of two-way mobile conversational video services. Other audio services are also getting upgrades such as interactive voice video response (IVVR), video conferencing and video ringback, which are on the verge of mass market adoption. In fact, almost 64 percent of the world’s mobile traffic is forecasted to be video by 2013, growing at a CAGR of 150 percent between 2008 and 2013. Of all geographic regions in 2013, Western Europe will have the most mobile video traffic, or roughly three-quarters of its overall mobile data traffic.1

While one-way video streaming services are increasingly delivered across mobile packet access networks to 3G devices, conversational two-way or N-way video services have more stringent requirements for delay and packet loss, making it difficult to deliver conversational video services to mobile subscribers expecting a high quality of service. In response to these challenges, many mobile service operations deploy video services based on 3G-324M standards in order to offer reliable quality of service (QoS) over a 3G mobile access circuit compared to an IP-based packet access service.

In the core of a 3G mobile network, operators are well on their way to migrating to cost-efficient IP-based service delivery architectures including IP Multimedia Subsystem (IMS). For voice calls, a 3G mobile voice circuit gets converted to IP audio packets using voice media gateways. However, most voice gateways don’t support 3G-324M protocols, driving the need for operators to deploy separate, specialized 3G-324M video media gateways, which convert 3G mobile video circuits into IP-based audio, video and signaling packet streams. The business challenge is 3G-324M video media gateways can cost up to ten times the price per port of a voice media gateway, resulting in a significant economic barrier for mobile service providers wanting to offer conversational video services at pricing levels that will achieve mass market adoption.

Another approach is to provide 3G-324M mobile access from directly inside the IP media server, which is already in the core service delivery architecture providing IP-based audio and video media processing for a broad range of 3G mobile services. This alternative approach of integrating 3G-324M within the IP media server eliminates the need for expensive, dedicated 3G-324M video gateways and improves the economics for 3G conversational video services.

This whitepaper explains how mobile operators can deploy video services on the RadiSys Convedia® Media Server, which is easier to manage and reduces system cost by eliminating the need for an additional dedicated video gateway. This solution is part of a broader framework, called RadiSys Integrated Mobile Media Server (IMMS), designed to enhance the mobile service provider’s ability to generate profitable 3G mobile revenues across a complete spectrum of content streaming and conversational mobile services.

THENEEDFOR3G-324MVIDEOIN3GMOBILENETWORKSToday’s 3G mobile networks use a combination of circuit-switched and packet-switched wireless access technologies. Members of standards bodies, like the Third Generation Partnership Project (3GPP), expect mobile networks will eventually become exclusively packet-switched. Packet-based mobile networks work effectively today for one-way video services, like playing back video clips or streaming video content from the Internet to a 3G mobile device. However, packet-based mobile access networks are also susceptible to performance issues like varying availability of mobile bandwidth, packet delay, jitter, packet loss or audio-video synchronization (i.e., lip-sync), which can wreak havoc on delivering reliable conversational video services. Hence, circuit-based mobile access technology continues to be the preferred approach for supporting reliable, high-quality interactive or conversational mobile video services.


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3G-324M was designed to deliver reliable, high quality two-way conversational mobile video services. The 3G-324M protocol has been broadly adopted across mobile access networks as a solution to the QoS limitations of packet networks across a wireless air interface. This is achieved by sending media content, in two directions, across a dedicated 64 Kbps circuit-switched connection. As a result, each call has a guaranteed level of service for both video and audio components, enabling a higher quality video call experience.

THE3G-324MPROTOCOLANDSTANDARDSWidespread compliance with the 3G-324M standard is a key ingredient in the growth of 3G conversational video services. Developed under the auspices of the 3GPP (GSM) and 3GPP2 (CDMA) networking standards organizations, 3G-324M is not just one standardized communications protocol, but is a suite of protocols that synchronizes the interaction of voice and video communications in a deterministic fashion between the circuit-switched 3G wireless radio access network and the core network.

THE3G-324MPROTOCOLSUITEThe 3G-324M protocol suite, depicted in Figure 1, provides for multiplexing and demultiplexing of audio, video and H.245 signaling on a 64 Kbps circuit-switched connection. Along with the compression efficiencies inherent in codec technology today, this minimal bandwidth can deliver multiplexed audio, video and control information over the same channel while delivering a quality, interactive video experience for the user.

H.223The key functions of the H.223 protocol include:

Interleaving video, audio, data and control streams into a combined bit stream.

Dynamic allocation of bandwidth within a single 64 Kbps channel amongst the individual streams.

Error detection and correction.

H.2453G-324M uses H.245 as a terminal control protocol and performs the following key functions:

Master-slave determination is provided to determine which terminal is the master at the beginning of the session.

Capability exchange is provided to exchange terminal capabilities, such as optional modes of multiplexing, type of audio/video codecs, data sharing mode and its related parameters, and/or other additional optional features.

Logical channel signaling is provided to open/close the logical channels for media transmission.

Round-trip delay measurement is provided to enable accurate quality characteristic measurement.

VOICECHANNEL—THEAMRCODECThe 3G-324M specifications define the Adaptive Multi-Rate (AMR) codec as mandatory, but also include the use of G.723.1. The AMR codec was originally developed and standardized by ETSI for GSM cellular systems. Optimized for mobile networks, it dynamically adjusts the number of bits allocated to voice coding and error control, providing the best possible voice quality based on radio conditions.

THEVIDEOCHANNELThe 3G-324M standard specifies the H.263 codec as mandatory, with H.264 as a recommended video processing codec that is commonly supported in 3G-324 deployments. H.263 is a legacy video codec that is used by many existing H.323 wireline video devices. However, resiliency and high efficiency make the H.264 codec particularly well suited for 3G-324M mobile environments. MPEG-4 is much more flexible and offers advanced error detection and correction services, which is beneficial when delivering video over a wireless network.

3GMOBILENETWORKINTEGRATIONWITHIPSERVICESCOREToday, IP packet networking technology is increasingly deployed in the core of a 3G mobile network. However, true end-to-end IP connectivity that reaches out from the core across the wireless radio network to an IP-enabled mobile handset is still quite rare in today’s networks, even in 3G UMTS and CDMA2000. More common is the 3GPP Release 99 architecture representation shown in Figure 2, composed of three functional areas: the Radio Access Network (RAN), Core Network (CN) and 3G Services Architecture.

The RAN is essentially the “wireless” part of the mobile network. These components are dispersed geographically to provide radio network coverage for subscribers using mobile handsets. Although the RAN has some packet data paths (for Internet access or SMS services), it is still primarily a circuit-switched domain with the Mobile Switch Controller (MSC) and Home Location Register (HLR) representing the heart of call processing in the network. These components switch voice circuits, identify subscribers with the services they have signed up for, plus manage roaming and provide connectivity to the

3G-324M OVER 64Kbps Circuit (DS-0)

3G-324M PROTOCOL PROCESSING

H.223 AUDIO/VIDEO/

CONTROL MULTIPLEXING

AMR AUDIO

H.263 VIDEO

H.245 CONTROLSIGNALING

3G CIRCUIT-SWITCHED

RADIO ACCESS NETWORK

3G-324MHANDSET

Figure 1. 3G Video Services using the 3G-324M Protocol


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PSTN off-network calls. For example, if an inbound call is requesting a conferencing service, the CN would hand-off the call to the 3G services architecture where conferencing-specific service processing is performed.

The Core Network integrates with a centralized 3G Services architecture using the following service elements:

Softswitch, orchestrating service requests.

Voice media gateway, performing voice circuit to packet conversion.

Application server, running the service application (service logic).

Media content server, staging audio content inside the mobile operator’s network.

IP media server, interfacing with above elements to deliver IP audio (and video) packet processing under the control of the application server.

Starting on the left of Figure 2, voice signals from mobile handsets are aggregated across circuit-switched connections into Mobile Switch Controllers. Many enhanced services are then handed off to voice media gateways, where the circuit is converted into Real-Time Protocol (RTP) audio packets. Once in the cost-efficient IP services core, the RTP audio packets aggregate on the IP media server, specifically designed to provide scalable and highly-efficient media processing functions such as

media play, record, mixing and tone detection. These functions are applied to the RTP media streams based on control commands from the softswitch or application services to support numerous enhanced audio services including network announcements, ringback tones, conferencing, audio advertising, messaging and prepaid calling cards, along with all the Interactive Voice Response (IVR) sessions for a mobile user to subscribe to and utilize all these services.

In traditional networks, each new service typically required its own dedicated service processing element, which integrates circuit termination, control logic and media processing hardware in a single, monolithic product. When a mobile operator added a new service or feature, a new piece of service processing equipment was often required. Over time, the end result is a room full of service nodes, often from different vendors, with the associated integration challenges, operational headaches and limited flexibility to rapidly add the next new service.

An important take-away from this section is that all the network elements described in this architecture are commonly accepted, yet functionally distinct components that form the foundation for a scalable next-generation IP services architecture for supporting a broad range of real-time, high-quality interactive audio services. This is also the baseline architecture from which a mobile operator would need to add capabilities for supporting conversational video services as well.

RADISYS CONVEDIA

MEDIA SERVER

NETWORK VIEW

FUNCTIONAL VIEW

MOBILE ACCESS NETWORK

3G CORENETWORK

3G SERVICESARCHITECTURE

AUDIO RTP

MOBILE SWITCH

CONTROLLER (MSC)

HOME LOCATION REGISTER

(HLR) APPLICATIONSERVER(S)

2G/3G AUDIOHANDSET

2G/3G AUDIOHANDSET

VOICE MEDIAGATEWAY

MEDIA CONTENTSERVER(S)

SIPSOFTSWITCH

RTSP,NFS3G CIRCUIT-

SWITCHEDRADIO ACCESS

NETWORK

RADISYS CONVEDIAMEDIA SERVER

VOICE MEDIA GATEWAY

3G AUDIO CIRCUIT

AUDIO CIRCUIT TO

RTP PACKETCONVERSION

AUDIO OVER RTP

MEDIA PROCESSING – MEDIA PLAY – MEDIA RECORD – MEDIA MIXING – TONE DETECTION

SIGNALING PATH 3G AUDIO CIRCUIT (AMR) RTP AUDIO PACKETS (AMR)

Figure 2. Today’s 3G Mobile Architecture with VoIP Services Core


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ADDINGCONVERSATIONALVIDEOSERVICESTOA3GMOBILENETWORKINFRASTRUCTUREEarlier, this whitepaper described how 3G-324M is an accepted industry standard for delivering 3G conversational video services using a 3G circuit-switched radio access network.

Since the vast majority of voice media gateways don’t support 3G-324M protocol or video circuit terminations, many mobile operators are adding G-324M video media gateways to their 3G Services Architecture, as shown in Figure 3. This dedicated network element converts 3G-324M video circuits in the RAN into IP-based signaling streams shared with the softswitch or application servers, as well as audio and video RTP media streams.

Most IP media servers can support RTP video packet processing alongside audio processing on the same platform, so just a simple capacity or software feature upgrade on the IP media servers introduced in the baseline architecture is all that would be required to add video media processing to the 3G services architecture.

Although a 3G-324M video media gateway offers a straightforward way to enable video-capable mobile networks, it’s a relatively expensive solution. These gateways can cost up to ten times the price per port compared to voice media gateway equipment, requiring mobile network operators to make sizable investments as video goes mainstream. Another architectural drawback is a new element in the call path, which introduces another source of network delay. Network operators may experience video quality and signaling delay problems caused by exceeding the network delay budget when both video gateways and media servers are in the call path.

If this architecture prevails, 3G-324M video media gateways may replace voice-only gateways and preclude many TEMs from selling their existing VoIP products into the growing mobile video opportunity. However, another architectural approach is to divide the tasks performed by the 3G-324M video media gateway between the existing

voice media gateway and the IP media server.

RADISYS CONVEDIA

MEDIA SERVER

NETWORK VIEW

FUNCTIONAL VIEW

3G-324MVIDEO MEDIA

GATEWAY


3G CORENETWORK


AUDIO RTP

AUDIO RTP

VIDEO RTPMOBILE SWITCH

CONTROLLER (MSC)



2G/3G AUDIOHANDSET

3G VIDEOHANDSET

VOICE MEDIAGATEWAY


SIPSOFTSWITCH

RTSP,NFS3G CIRCUIT-

SWITCHEDRADIO ACCESS

NETWORK

RADISYS CONVEDIAMEDIA SERVER3G-324M VIDEO MEDIA GATEWAY

3G-324M OVER 64Kbps

DS0 CircuitAUDIO OVER

RTP

VIDEO OVER RTP


H.223 AUDIO/VIDEO/

CONTROL MULTIPLEXING &DEMULTIPLEXING

AMR AUDIO

H.263 VIDEO

H.245SIGNALING

MEDIA PROCESSING – MEDIA PLAY – MEDIA RECORD – MEDIA MIXING – TONE DETECTION – VIDEO TEXT OVERLAY

3G-324MHANDSET

RTP VIDEO PACKETS (H.263)SIGNALING PATH

3G AUDIO CIRCUIT (AMR) 3G VIDEO CIRCUIT (3G-324M, AMR, H.263)

RTP AUDIO PACKETS (AMR)

Figure 3. Today’s 3G Mobile Architecture Including 3G-324M Video Gateways


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ELIMINATINGTHE3G-324MVIDEOMEDIAGATEWAYMoving forward, the 3G-324M video gateways can be eliminated altogether. This can be achieved by configuring a pass-through or “clearmode” on the voice media gateway and performing 3G-324M protocol processing on the IP media server, as shown in Figure 4. Clearmode,2 which is already available on most voice media gateways, ignores the content of the 64 Kbps bitstream and simply converts the H.223 data stream inside the 3G-324M circuit to H.223 inside an RTP media stream. The RTP stream carrying the H.223 payload is forwarded to the IP Media server, which now interprets the H.223 into an H.245 signaling stream, as well as H.263 video and AMR audio media streams. The audio and video media streams are then handed over and processed by the existing IP media processing functions in the exact same network element. This network architecture has the same network elements—no more, no less—as the baseline voice-only architecture, shown in Figure 2.

Doing away with traditional 3G-324M video media gateway provides significant cost, performance and network management advantages. Moving the 3G-324M protocol processing to the IP media server significantly reduces the cost per port for supporting conversational video services, because this approach essentially reuses the exact same architecture deployed for the baseline voice-only IP services architecture. Fewer network elements in the call path also increases performance by reducing call path delay, hence leading to higher video quality. Consolidating network elements also simplifies network management and lowers ongoing operations costs.

This novel and cost-effective solution also presents commercial advantages to TEMs competing for mobile video business with their existing VoIP voice gateway products.

RADISYS CONVEDIA

MEDIA SERVER

NETWORK VIEW

FUNCTIONAL VIEW

3G-324MVIDEO MEDIA

GATEWAY


3G CORENETWORK


AUDIO RTP

MOBILE SWITCH

CONTROLLER (MSC)



2G/3G AUDIOHANDSET

2G/3G AUDIOHANDSET

3G VIDEOHANDSET

VOICE MEDIAGATEWAY


H.223 OVERRTP

SIPSOFTSWITCH

3G CIRCUIT-SWITCHED

RADIO ACCESS NETWORK

3G-324M OVER 64Kbps DS0 CIRCUIT

3G AUDIOCIRCUIT

AUDIORTP

RADISYS CONVEDIAMEDIA SERVER

VOICE MEDIAGATEWAY


H.223 AUDIO/VIDEO/

CONTROL MULTIPLEXING & DEMULTIPLEXING

AMR AUDIO

H.263 VIDEO

H.245SIGNALING

MEDIA PROCESSING – MEDIA PLAY – MEDIA RECORD – MEDIA MIXING – TONE DETECTION – VIDEO TEXT OVERLAY

AUDIO CIRCUIT TO RTP PACKET CONVERSION

PASSTHRU“CLEARMODE”

H.223OVERRTP

3G-324MHANDSET

RTSP,NFS

RTP VIDEO PACKETS (H.263)SIGNALING PATH

3G AUDIO CIRCUIT (AMR) 3G VIDEO CIRCUIT (3G-324M, AMR, H.263)

RTP AUDIO PACKETS (AMR)

Figure 4. Alternative 3G Audio Video Architecture with Integrated 3G-324M Support in the Media Server


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GETTINGREADYFORMOBILEVIDEOAvailable today, the RadiSys 3G-324M Services Solution allows mobile network operators to cost-effectively upgrade their existing networks to handle video. The RadiSys Convedia CMS-9000 Media Server, with integrated 3G-324M support, interprets and splits the H.223 bitstream into audio RTP media stream, video RTP media stream and signaling channel. This functionality is seamlessly integrated in the same hardware platform with the full complement of existing audio, video, fax and speech media processing functions supported by RadiSys Convedia Media Servers (Figure 5).

The RadiSys 3G-324M Services Solution is part of a larger framework, called RadiSys Integrated Mobile Media Server (IMMS), that delivers a consolidation of disparate service processing equipment into a single, cost-efficient carrier-class network element. This framework better positions mobile operators to generate new service revenues at lower cost, which is critical for successful mass market deployments. IMMS supports both circuit-based and packet-based mobile video networks, RTSP (Real-Time Streaming Protocol) streaming and interactive RTP services. In addition to savings from equipment consolidation, the IMMS framework lowers deployment and operations costs by delivering interoperability between various mobile access technologies, codecs and file formats.

CONSOLIDATIONLOWERSMOBILENETWORKCOSTService providers are adding video to traditional audio-only mobile networks and offering enhanced video service offerings, such as two-way conversational video, interactive voice video response (IVVR), video conferencing and video ringback. Today’s solutions often dictate the requirement for separate, dedicated 3G-324M video media gateways, which add costs and complexity to the mobile services infrastructure. Fortunately, mobile operators now have a better approach to respond to the growing demand for mobile video services. It’s no longer necessary to deploy traditional 3G-324M video gateways, because it’s possible to consolidate the necessary functions onto existing voice media gateways and IP media servers. Most of today’s VoIP voice gateways only require a straightforward configuration change, while 3G-324M protocol processing is integrated with existing RTP media processing functions in the IP media servers.

The solution summary and benefits of integrated 3G-324M support includes:

Elimination of traditional 3G-324M video gateways.

Termination of 3G-324M video circuits alongside audio circuits on existing VoIP voice gateways.

– The voice gateway is configured into a “pass-through” mode that simply converts the H.223 bitstream from the mobile access circuit to an RTP media stream carrying H.223.

Consolidation of 3G-324M protocol processing and IP media server functionality.

– Adding 3G-324M protocol processing alongside existing Video RTP media processing functions makes for a cost-efficient architecture.

Simplification of network management through network element consolidation.

Improved video quality due to fewer network elements in the call path, which reduces call path delay.

It is estimated that the RadiSys IMMS solution, with integrated 3G-324M support on a Convedia CMS-9000 media server, will offer mobile service providers over 50 percent capital cost and ongoing operational cost savings compared to existing video service delivery architectures using dedicated and separate 3G-324M mobile video gateway equipment.

For more information about the RadiSys Integrated 3G-324M Solution on the new Integrated Mobile Media Server (IMMS), please visit http://www.radisys.com/Products/Media-Servers.html.

Figure 5. RadiSys Convedia® CMS-9000 Media Server

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CorporateHeadquarters5445 NE Dawson Creek Drive

Hillsboro, OR 97124 USA Phone: 503-615-1100

Fax: 503-615-1121 Toll-Free: 800-950-0044

www.radisys.com [email protected]

©2010 RadiSys Corporation. RadiSys is a registered trademark of RadiSys Corporation. Convedia, Microware and OS-9 are registered trademarks of RadiSys Corporation.

Promentum, and Procelerant are trademarks of RadiSys Corporation. *All other trademarks are the properties of their respective owners.

10-189-00 January 2010

REFERENCES:1 Source: Cisco Visual Networking Index: Forecast and

Methodology, 2008-201 from June 9, 2009 found at http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11-520862.html.

2 See http://www.faqs.org/rfcs/rfc4040.html for more details on RFC4040 and Clearmode.

delivering video services over 3g-324m mobile networks

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