IPTV Mobile IPTV Approaches, Challenges, Standards, and QoS Support IPTV is defined as multimedia services, such as TV, video, audio, text, graphics, and data, delivered over IP-based networks managed to support quality of service (QoS), quality of experience, security, interactivity, and reliability. Mobile IPTV extends those services to mobile networks. The authors discuss mobile IPTV standardization’s status, related approaches in the field, and technical challenges to enhancing mobile IPTV services. Given the critical role of QoS in the technology’s widespread adoption, the authors also propose an efficient signaling scheme to support QoS for seamless mobile IPTV services. obile IPTV lets mobile users In this article, we describe the cur- Soohong Park transmit and receive multi- rent status of mobile IPTV standardiza- Samsung Electronics M media traffic, such as TV sig- tion as well as mobile IPTV approaches nals, video, audio, text, and graphics, and technical challenges. Addition- Seong-Ho Jeong through IP-based networks with the ally, we propose an efficient signaling Hankuk University support of quality of service (QoS) and scheme to support QoS for seamless of Foreign Studies quality of experience (QoE), security, mobile IPTV services. QoS support is mobility, and interactivity. In short, critical for video delivery systems, es- mobile IPTV extends many IPTV ser- pecially in the mobile environment, and vices to mobile users. a requirement for viewer satisfaction. To coordinate and promote develop- ment of global IPTV standards, the ITU- Architectures and Approaches T in 2006 formed a focus group called ITU-T defines the IPTV architecture1 FG IPTV, which took into account the and further classifies it into next- existing work of ITU-T study groups and generation-network (NGN)-based and other standards development organiza- non-NGN-based architectures. In this tions. Then, in January 2008, the IPTV article, we address non-NGN-based ar- Global Standards Initiative (IPTV-GSI) chitectures for mobile IPTV services. In took over the IPTV standardization role. future work, we’ll incorporate the NGN- MAY/JUNE 2009 1089-7801/09/$25.00 © 2009 IEEE Published by the IEEE Computer Society 23 Authorized licensed use limited to: University of Texas at Arlington. Downloaded on April 24,2010 at 22:39:32 UTC from IEEE Xplore. Restrictions apply. IPTV Network Sender Receiver Wired equipment Wireless Digital Video Broadcasting’s Convergence of Broadcast and Mobile Services (DVB-CBMS; • Non-NGN-based architecture www.dvb.org/groups_modules/technical Network Sender • NGN IMS-based architecture _module/tmcbms), DVB IP Infrastructure (DVB- Wireless equipment • NGN non-IMS-based architecture IPI; www.dvb.org/groups_modules/technical_ module/tmipi), and the World Digital Multimedia The network includes IPTV access routers or Broadcasting (WorldDMB) Forum (www.world source generator points of attachment Mobile terminal dab.org) are key standards groups in this area. DVB-CBMS is developing protocol specifications Figure 1. Mobile IPTV architecture. In the first stage, a wireless for bidirectional, IP-based broadcasting over interface enables communication between the access network and DVB-H, the specification for bringing broadcast the receiver. In the second stage, the wireless section extends to the services to battery- powered handheld receivers sender, giving the sender’s and receiver’s devices mobility. (NGN: (www.dvb.org/groups_modules/technical next-generation network; IMS: IP-based Multimedia Subsystem) _module/tmh). DVB-IPI specifies technologies on the interface between an IP network and retail receivers, enabling the end user to receive DVB based mobile IPTV approach, which considers services over IP-based networks. The WorldDMB the IP-based Multimedia Subsystem (IMS). Forum is enhancing and extending Eureka 147, Figure 1 shows an overall mobile IPTV originally developed for digital radio applica- architecture. In the first stage, a wireless in- tions, to support IP-based and video services. terface enables communication between the Although this mobile TV plus IP approach access network and the receiver (mobile IPTV is classified as mobile IPTV, the use of broad- terminal). Because IPTV is access agnostic ac- casting networks might cause loss of IP indi- cording to ITU-T’s definition, various wire- viduality, such as point-to-point interactive less access networks, such as wireless LAN communication and personalized services. (WLAN),2 WiMAX,3 and cellular networks,4 can exist. Each wireless technology has its IPTV Plus Mobile own characteristics, which service providers Is networked TV the future of television? A lot should carefully consider when deploying mo- of services similar to IPTV are already on the bile IPTV. market, and more are in progress. Telco giants In the second stage, the wireless section ex- say IPTV is the new source of revenue. IPTV tends to the sender so that both the sender’s services originally targeted fixed terminals and receiver’s devices can be mobile. Moreover, such as set-top boxes, but mobility possibili- user-created content is becoming more popular ties have grown out of the fixed mobile con- in the Internet community; any mobile user can vergence trend. create IPTV content and provide it to other mo- The Alliance for Telecommunications In- bile IPTV users. dustry Solutions (ATIS) in the US and ITU-T Some of the approaches for mobile IPTV ser- IPTV-GSI internationally are primary standards vices we’ll discuss in this section are already in organizations in the IPTV plus mobile field. use. From the users’ perspective, no big func- Mobile IPTV specifications development is a tionality differences exist among the approach- relatively new effort. ITU-T FG IPTV has col- es, but the detailed technologies differ. lected requirements for IPTV, including mobile IPTV. ATIS, however, has yet to show interest in Mobile TV Plus IP mobility support. The main problem of this ap- Using traditional digital broadcast networks, proach is slow development, even for fixed wire- mobile TV plus IP delivers IP-based audio, less IPTV only. video, graphics, and other broadband data to mobile users.5 This approach aims to build an Cellular environment in which stable broadcasting facil- The Open Mobile Alliance’s Broadcasting Work- ities and content combine with diverse Internet- ing Group (OMA BCAST) is working on technol- based services. Additionally, mobile TV plus IP ogies for providing IP-based broadcast ser vices uses wide area wireless networks, such as cel- in the mobile environment. The technique’s lular networks, to support interactivity. main goals are to define an end-to-end frame- 24 www.computer.org/internet/ IEEE INTERNET COMPUTING Authorized licensed use limited to: University of Texas at Arlington. Downloaded on April 24,2010 at 22:39:32 UTC from IEEE Xplore. Restrictions apply. Mobile IPTV work for mobile broadcast and compile the set of the mobile terminal’s screen size when sending necessary enablers. A key feature of the cellular a video stream. approach is the bearer agnostic, which means it can adopt any broadcast-distribution network Bandwidth as its transport means. Although the wireless link’s effective band- OMA BCAST currently applies only to mo- width is growing rapidly, it won’t be suffi- bile terminals, but its specification might ex- cient for mobile IPTV until the 4G wireless pand to cover fixed terminals. network’s full deployment. Only then will the wireless link bandwidth become broad enough Internet to accommodate high-definition video ser- A product of the entertainment business, In- vices. Even when the 4G wireless network is ternet or Web TV comprises numerous Internet available, the bandwidth might not be suf- video services worldwide. With the Internet ap- ficient if bandwidth-greedy services such as proach, the model form depends on the business ultra-definition (UD) video emerge and the types and infrastructures it will support. number of users increases rapidly. The wire- Anyone can use this approach to play a role less link will always have less bandwidth than in the value chain; the user can be a content the wired link, and the number of high-band- provider, service provider, or consumer. This width applications will continue to increase. flexibility enables a universe of highly diversi- Therefore, bandwidth-aware solutions are al- fied and dynamically independent production, ways desirable for mobile IPTV services in the as well as a global reach. wireless environment. However, QoS isn’t guaranteed because the approach is based on the best-effort service Wireless Link model. Nevertheless, through its rapid adapta- The wireless link is vulnerable to physical fac- tion to customer needs, the Internet approach tors. When the mobile IPTV terminal moves might become dominant in the near future. around, packets can suffer quality degradation from such factors as shadowing and fading as Technical Challenges they travel through wireless channels. Even Mobile IPTV services must overcome several when mobile IPTV terminals are stationary, obstacles to a successful launch and wide use. temporal reflectors and obstacles in the wire- Because of a lack of consensus, we don’t pres- less environment can affect the received sig- ent detailed solutions to each technical issue in nal quality and cause burst packet losses. Such this section. quality degradation is intrinsic in the wireless Mobile IPTV implies at least one wireless link. So, the mobile IPTV servers and terminals link between the source, such as a streaming should react adaptively to the wireless link’s server, and the destination, such as a mobile varying conditions. terminal. Therefore, most of the technical chal- lenges are related to the wireless link. Service Coverage The purpose of mobile IPTV devices is to pro- Terminal Capabilities vide anytime, anywhere access to IPTV servic- Moving IPTV content from a standard home es. However, it’s virtually impossible to deploy display to a mobile terminal with a small screen a wireless network that covers all geographi- raises various concerns.