Applications and Supporting Technologies of 3G Services

Along with the development of mobile communications technology, mobile service applications have become a new focus. However, the application of new technologies lags behind the development of technologies. Solutions to the problems of how to satisfy customers´ individualized demands, how to build effective commerce modes, and how to make a perfect value chain of network operators, Internet content providers, value-added service providers and terminal providers become actually more urgent.

  The launch of 2.5G systems and 3G systems and the interworking of the Internet and mobile networks bring along more demands on basic voice communication, mobile data communication and multimedia communication.

  Mobile data communication includes SMS (Short Message Service), EMS (Enhanced Multimedia Service), MMS (Multimedia Messaging Service), email service and Web browsing, while multimedia communication refers to picture transmission, animation transmission and video transmission.
Handsets are gradually changing from simple talk tools into data and information terminals. People in some particular regions have begun to use GPRS (General Packet Radio Service) handsets to buy metro tickets and Coke.

  In the future, people may finish the online shopping and daily payment by their handsets. According to relevant market investigation, about 24% of the existing mobile users will become the main user group of the future mobile data services. The mobile data services they are interested in most include communication (e.g. SMS and email service), entertainment, information services(e.g. shopping, business and investment information), interactive programs
(e.g. chat) and mobile business services (e.g. product/service purchase). It can be said that people´s life style, culture and customs are changing along with the development of mobile services.

1 Mobile Multimedia Messaging  Service
MMS is a multimedia communication mode based on the store-and-forward mechanism. Different from SMS and EMS, MMS has no restriction on the amount and complexity of information contents. So MMS can be used to transmit short messages in texts, as well as pictures, videos and audios.

  MMS makes it possible for operators to develop various new mobile services. So, it is generally regarded as a key impetus for the opening and development of GRPS and 3G markets. It is forecasted that MMS income will exceed 5 billion US dollars in 2004. In 2006, the figure will reach 15 billion US dollars, and mobile subscribers using MMS handsets will account for 50% of the global handset users.
Entertainment, pictures and point-to-point applications are three main applications of MMS. The application and popularization of MMS depend on strengthening terminal users´ will to share entertainment and graphic information with others, to DIY multimedia messages with information on hand, and to download all kinds of MMS information.

  The initial development of MMS was focused on end-to-end services, which is similar to the present SMS. Along with the application of value-added services, simple pictures began to be transmitted. Though the present 2G and 2.5G networks can support MMS applications, only the future 3G network can bring the application of MMS into full play. The future handsets will support real-time services such as news, entertainment and games, and what users see will be animations and videos.
At present, on the existing GPRS network, the size of a MMS message, according to relevant 3GPP specifications, is limited in 30 000 bytes, and can reach 100 000 bytes in the future. This determines that MMS on a GPRS network cannot offer such applications as playing an MP3 song and a movie.

  Therefore, the main applications of MMS are limited to forwarding pictures, playing animated Gifs less than 10 frames and playing video contents within 5 seconds.

  The following problems should be resolved for the application of MMS and its development on 3G networks:

• The Interfaces between the MMS system and the value-added service system are not yet standardized, which hinders the service development.
• Problems in interworking, channel jam, roaming and inter-operation have impact on the quality of services.
• The information contents, handset prices, customer habits and charges influence the cultivation of the MMS market.
  

It´s commonly accepted that the well-developed MMS technology should support all kinds of information formats available now, such as images (JPEG, GIP89a, WBMP), videos  (ITU-TH.263, MPEG-4) and audios (MP3, MIDI, WAV, AMR/EFR).

2 Streaming Media
Different from the traditional multimedia, streaming media is characterized by using the variable bandwidth technology to run data media in the form of "stream". It can now support playing high-quality audio and video programs online at the speeds of from 28 kb/s to 1 200 kb/s. As a typical 3G service, streaming media represent animated images and information services.

  Apple, Cisco, Lasenna, Philips, Sun and several other companies jointly founded the Internet Streaming Media Association (ISMA) in December 2000. They intended to promote the streaming media market and constitute relatively open standards and implementation protocols. However, it is a long way for streaming media to realize its application on 3G networks. First of all, it´s hard to determine a dominant media compression technology out of Real, WMT and ISO MEPG-4. Besides, IETF´s open standards for stream transmission network protocols, such as HTTP, FTP, RTP, RTSP and RTCP, are the only choice for cross-platform applications, but they can´t support intelligent stream as well as Microsoft´s MMS protocol does.

  As to 3G networks, the existing WCDMA network has not yet adopted the R5 standard, so it will take quite a long time for the mobile network to become an all-IP network. On one hand, the QoS of the network layer is hardly possible to meet the demands of streaming media transmission. On the other hand, the network congestion model of the TCP protocol is not suitable for the wireless channel of mobile networks, so the application of all the streaming media transmission carrier protocols based on TCP/IP protocol stacks is blocked.

  Meanwhile, the cost and complexity of terminals supporting the streaming media transmission may increase since the MPEG-4 decoding component should be added to these terminals to send wireless video data in MPEG-4.
Except for the available server cluster, there are no other better methods for 3G networks to solve the flexibility of streaming media value-added service system and support users´ increasing concurrent access.

  The successful application of streaming media technology on 3G networks definitely requires the complete cooperation of technology developers, content providers, network operators and users.
3 Supporting Technologies for 3G Services According to the general development trend of mobile communications, operators´ focuses have shifted from subscriber growth to service quantity and new service growth, and from technology development to market development such as service and application development.

  Establishing relevant open standards are the key point to make full use of 3G network advantages, to promote the development of mobile data services, to satisfy more personalized user demands, and to bring operators actual profits. To build standard interfaces between network layers on the basis of open standards is beneficial for operators to choose equipment for transport layer, access layer, core control layer and service layer among vendors. It also benefits the service interworking and user roaming between operators using the same 3G system.

3.1 Open Service Architecture
The concept of Virtual Home Environment/Open Service Architecture (VHE/OSA) has been put forward for WCDMA R99. OSA, proposed by 3GPP, is an open service platform for rapid service deployment. It separates the service deployment from the carrier network in order for the third party to have a chance to provide services. It has advantages in network interworking and in the rapid deployment of new services. OSA adopts an open, standard and uniform network Application Program Interface (API), which allows the third party to effectively upload services.

  OSA API referred to JAIN and PARLAY protocols, and keeps consistent with them. OSA supports the CAMEL service environment. An OSA platform not only fully supports existing CAMEL services, but also helps to deploy new CAMEL services.

  Different from 2G, the 3G network enables the service function standardization. Based on services, 3G develops the concepts of Service Capability and Service Capability Feature.

  Service Capability is an aggregation of interfaces needed for special service functions, which consists of network and terminal functions (e.g. the standard toolkit, the application and protocol interface and the basic transmission and control mechanism).

  Service Capability Feature is the logic abstract of capabilities needed to realize services, such as the information capability feature that includes information receiving, storing, transfering, forwarding, uploading, downloading and browsing, which are necessary for realizing an information service. The logic entity that provides service capability is called as Service Capability Server.

  Since the standardization is directly imposed on services themselves on 2G networks, one service can only be realized by one standard implementation measure, which impedes the rapid introduction of services from the third party and new service creation. So it is difficult to create new services and fully satisfy users´ individualized service demands.

  On a 3G network, a special service can be abstracted as an aggregation of some service capacity features, and each service capacity feature can be concretely realized by different service capabilities according to different carrier networks. This manifests the diversification and flexibility of 3G service creation.

3.2 Open Mobile Architecture (OMA)
The situation that services are only developed by content providers doesn´t meet abundant service demands anymore. WCDMA networks in R5 version will be all-IP networks, and the network convergence and service generalization will be a new focus, though the service is mainly presented by end-to-end IP multimedia services. Involved in realizing mobile applications and framing service standards that are independent of mobile interfaces and core network technologies, OMA may become a common standard of 3GPP and 3GPP2.

  OMA Organization was found in June 2002, and proposed OMA, aiming at attracting more participation in making game rules. Its basic tenets are as follows:

• The development of mobile products and services should be based on global and open standards and interfaces, rather than on incompatible ones.
• The application layer should be independent of carrier networks such as GSM, GPRS, CDMA 2000 and WCDMA networks.
• The application architecture  and service engine should be independent of any operation systems.
• Applications and platforms should be interworking, supporting the seamless roaming among different regions and supporting different technologies.
  

OMA is rather user-oriented in order to make applications and services independent from operators and operation systems and realize network interworking through seamless roaming. At present, the main OMA service applications are the mobile multimedia short message, JAVA and XHTML services.

Manuscript received: 2003-09-16