By Greg Blumenthal, Principal Engineer, Communications Platforms
The following is an excerpt of the application note, Mobile TV and Video: Real-World Experiences .
Mobile phones are not just for talking anymore. Today’s tech-savvy consumers view their phones as an entertainment center, as well as a communication device.
As a result of the build-out of 3G networks, which is fueling mobile video use, IDC analysts expect that revenues from mobile TV and mobile video in Western Europe alone will reach nearly $2 billion by 20091. In fact, Yankee Group has found that as soon as consumers switch to a 3G phone, their usage of non-messaging mobile data applications, such as video, increases by 70 percent2. This growth presents mobile operators with a ripe opportunity to deliver live TV right into the hands of their waiting subscriber base.
3G-324M and Mobile TV
Widespread compliance with the 3G-324M standard is a key ingredient in the growth of the mobile TV market. The 3G-324M standard provides multiple benefits for mobile TV deployment, including:
- Ubiquity—Almost all W-CDMA-based 3G handsets on the market today support the 3G-324M protocol. There is no need to wait for more handset vendors to introduce this feature or to roll out the service on only a few handsets that can support mobile TV.
- Infrastructure Costs—The 3G-324M protocol uses the existing 3G network for all audio and video. There is no need to build a costly parallel network solely for transmitting mobile TV data.
- Interactivity—The 3G-324M protocol includes a specification for sending dual-tone multi-frequency (DTMF) style information from the handset. For mobile TV, these key presses can be used to change the channel; control pause, fast forward, and rewind; as well as to provide interactive services, such as televoting. Latencies over the TDM connection are kept to a minimum, so the reaction to a user’s input typically will be seen in about 0.5 seconds.
In a 3G mobile TV application, a mobile subscriber simply keys in a short access number and uses the video-calling feature of the handset to call in to the 3G mobile TV system. After the system answers the call, the user is presented with a choice of channels. Channels are selected using the telephone keypad, and the user can change the channel whenever desired. The number of channels offered by a 3G mobile TV system is limited only by the imagination of the system developer and the availability of video content.
Tools Needed to Deploy 3G Mobile TV
A mobile TV application should include the following components for a fully functional system:
- 3G-324M gateway function, which forms a bridge between 3G-324M video calls from the mobile handset to the IP network that hosts the media components. On the 3G network side, the interface will be E1 or T1, using either Integrated Services Digital Network (ISDN) or Signal System 7 (SS7) ISDN User Part (ISUP) signaling. On the IP side, there will be separate audio and video streams, using the Real-Time Transfer Protocol (RTP) for transport.
- Video-enabled IP media server, which plays stored video clips across the IP network. The output of the server is separate audio and video RTP streams, which are sent to the 3G-324M gateway to deliver video to the end user’s handset. The media server uses an IP interface to enable integration with stream servers (used for live video streams) and to allow for IP-based video in the future. If the IP media server has a high level command interpreter, it can interface to the application server using a high-level language such as Voice Extensible Markup Language (VoiceXML). Otherwise, the interface to the application server could be a low-level media control protocol or direct application programming interface (API) control.
- Application server, which implements the actual user experience of the system by controlling the IP media server component. The definitions of channels, how to react when the user presses a key, and any interactive applications are handled here.
- Content server, which stores the video clips to be played and offers an interface for the content owners to upload their video clips. The clips are sent to the IP media server as requested by the user. The content server and application server often will be combined into one physical system. In some architectures, the content server, application server, 3G-324M gateway, and IP media server all will be combined.
- Video transcoder, which converts a wide variety of possible video formats into one of the specific video formats that can be used for 3G-324M. This component is required when a video source is not in a format suitable for sending directly to a 3G-324M mobile handset.
- Video stream server, which is used to transmit a live video stream to each viewer of that stream via the 3G-324M gateway.
- Live video encoder, which takes audio and video signals from a locally connected microphone and camera, or from an external source, and encodes them into audio and video RTP streams. These RTP streams are then sent to the video stream server for further distribution to each user.
NMS Offerings
NMS Communications offers two product families that can be used to create a 3G mobile TV system.
Vision VoiceXML Server
Vision VoiceXML Server gives application providers the ability to rapidly develop and deploy new, innovative VoiceXML-controlled voice and video applications in IP, public switched telephone network (PSTN), and 3G- 324M networks.
The Vision VoiceXML Server is fully compliant with W3 Consortium (W3C) VoiceXML 2.0 and 2.1 specifications. The Vision VoiceXML Server includes the 3G video gateway and video-enabled IP media server components in a single carrier-grade platform. It supports either ISDN or SS7 ISUP on the interface to the mobile network. The application server controls the Vision VoiceXML Server using industry-standard VoiceXML 2.1, which is extended to play video clips and make Real-Time Streaming Protocol (RTSP) connections to a stream server to play live video content. Figure 1 shows a typical architecture for a 3G mobile TV system using the Vision VoiceXML Server. (See the Product News section of this newsletter for information on the latest release of this product.)
Figure 1: 3G Mobile TV Using NMS Vision VoiceXML Server (click to view larger)
Video Access Toolkit and CG Series Boards
Video Access is the ideal development environment for meeting the demand for flexible, scalable, and cost-effective 3G mobile video solutions. Developers can rapidly implement new video solutions using the Video Access APIs in conjunction with NMS’s renowned Natural Access™ development environment and the CG Series of PCI and cPCI boards.
A developer creating a 3G mobile TV system uses the Video Access 3G-324M Gateway API to create the 3G-324M gateway component, and the Video Access Messaging API to create the video-enabled IP media server component. In most cases, these functions will share the same physical system and will use a single CG board. The same system may also be used as an application server and content server, if desired. The NMS Software Video Transcoder optionally may be added to the system to ensure that both video clips and live streaming video conform to the strict video encoding requirements of the 3G-324M protocol. (See the Product News section of this newsletter for information on the latest release of these products.)
Figure 2 shows a typical architecture for a 3G mobile TV system using Video Access software and CG Series hardware.
Figure 2: 3G Mobile TV Using Video Access (click to view larger)
A Growing Opportunity
The rising demand for mobile video services, such as mobile TV, has created major revenue opportunities for network operators and application developers. The advent of 3G networks worldwide provides an opportunity for mobile operators to open up new revenue streams and increase subscriber adoption rates by delivering unique and innovative applications and services. Mobile TV is not a simple medium, however, and developers face stringent performance requirements, multiple interoperability issues, and a variety of other technical challenges. Fortunately, they do not have to face these challenges on their own. Advanced platforms and toolkits available from industry leaders like NMS alleviate the technical complexities of mobile TV and give developers the resources they need to produce compelling and profitable applications.
1 IDC, “Western Europe Consumer Mobile Data Applications: Forecast and Analysis, 2004–2009,” November 2005.
2 Yankee Group, “European 3G Market Gains Momentum,” August 2005.