2010 International Conference on Data Storage and Data Engineering
Multimedia Distribution over IPTV and its Integration with IMS Mohammed Abdul Qadeer, Afaq Hasan Khan Department of Computer Engineering Zakir Hussain College of Engineering & Technology Aligarh Muslim University, Aligarh, India
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built on vendor- specific platforms without integration with Next-Generation Network (NGN) subsystems. Integration of IPTV with IMS platform can be a useful method of reducing the operating cost and investment costs. There is a growing standardization effort on the use of the 3GPP IP Multimedia Subsystem (IMS) as architecture for supporting IPTV services in carrier networks. The IP multimedia subsystem (IMS) was introduced by the Third Generation Partnership Project (3GPP) initiative as the architectural subsystem dedicated to control and provide multimedia services over a packet-based core network. Both ITU-T and ETSI are working on so-called "IMS-based IPTV" standards. This paper focuses on the various services, features of IPTV and how all these things can be blended with the IMS platform. Technical challenges also are discussed.
Abstract—Digital television has been evolving for several years. Recent evolutions in the technology have made it possible to deliver digital television services over fixed and mobile broadband network, which is commonly known as IPTV. IPTV is a system in which digital television services are provided using internet protocol over a network. The deployment of Internet Protocol-based television (IPTV) over different broadband access networks is made possible by the new types of broadband access networks and improved media coding algorithms. Many service providers have started to deploy triple play services over DSL including IPTV as an essential service component. However, each service in the triple play bundle (e.g. IPTV, VoIP) has its own unique servicecontrol framework and operations and billing support systems, increasing the complexity of the overall triple play service architecture therefore, there is a need of flexible network architecture. In this paper we discuss about the features of IPTV along with the integration of IMS and IPTV service platforms to reduce network complexity and provide a flexible network for new services. Keywords: IPTV, IMS, VoIP, DSL, NGN, 3GPP, VoD, triple play.
I.
INTRODUCTION
IPTV is an integration of voice, video, and data services using high bandwidth and high speed Internet access. Internet Protocol television (IPTV) provides digital television services over Internet Protocol (IP) for residential and business users at a lower cost. These IPTV services include commercial grade multicasting TV, video on demand (VoD), triple play, voice over IP (VoIP), and Web/email access, well beyond traditional cable television services, ref. fig 1. Internet Protocol Television (IPTV) will be the killer application for the next-generation Internet and will provide exciting new revenue opportunities for service providers. IPTV has a totally different infrastructure from conventional TV services which use a “push” approach in which contents are pushed to the users. IPTV is based on user’s choice, their needs and interests, thus following the “push and pull” approach. Therefore it has two way interaction between the operator and the user with the functions like forward, rewind and pause which are absent in the traditional cable TV networks. Although the IPTV standardization is ongoing, currently no real solutions are based on IPTV standardization from the relevant standard bodies. The current IPTV services are
978-0-7695-3958-4/10 $26.00 © 2010 IEEE DOI 10.1109/DSDE.2010.64
Fig 1: Various services provided by IPTV
II.
A BRIEF HISTORY
In 1994, ABC’s World News Now was the first television show to be broadcast over the internet, using the CU-SeeMe video conferencing software. Internet radio company AudioNet started the first continuous live webcast in January, 1998 [1]. The term IPTV first appeared in 1995 with the founding of Precept Software by Judith Estrin and Bill Carrico. Precept designed and built an internet video product named "IPTV". IPTV was an MBONE compatible Windows and UNIX based application that moved single and multi-source audio/video traffic, ranging from low to DVD quality, using both unicast and IP multicast RTP/RTCP. Precept was acquired by Cisco Systems in 1998.Cisco retains the "IPTV" trademark. Kingston Communications, a regional telecommunications operator in UK, launched KIT (Kingston Interactive Television), an IPTV over DSL broadband interactive TV service in 101
• TV programs are stored in local storage devices so that users can watch them anytime. • Gaming. • Yellow pages (local directory) and advertisements. • Photo albums.
September 1999 after conducting various TV and VoD trials. Kingston was one of the first companies in the world to introduce IPTV and IP VoD over ADSL [2]. III.
FEATURES/SERVICES OF IPTV
Worldwide interest shown by telecom operators is a direct result of the various rich facilities provided by IPTV. IPTV offers virtually limitless programming and on-demand content because only those channels which are selected by consumers are delivered over last-mile and broadband networks. IPTV brings together the benefits of broadband, the rapid adoption of home networking technology and the magic of software to give customers content where, when and how they want it. IPTV has unique features in addition to simply broadcasting ordinary TV programs over the Internet. IPTV can be incorporated with high-speed DSL access technologies, such as ADSL2, ADSL2+, and VDSL, as well as high-speed carrier-grade Ethernet and the emerging high throughput IEEE 802.11n wireless LAN. The advantages of Internet Protocol Television (IPTV) are vast as compared to its limitations, which is the main reason behind its rapid success. Its key features include:
IV.
HOW IT WORKS ?
IPTV covers both live TV (broadcasting) as well as stored video (Video on Demand). User requires either a personal computer or a set top box connected to a TV. Video content is typically compressed using either a MPEG2 or a MPEG-4 codec and then sent in an MPEG transport stream delivered via IP Multicast in case of live TV or via IP Unicast in case of Video-on-Demand. The broadcaster encodes the TV program into MPEG2 and sends the stream to the satellite uplink; ref fig. 2 .This video stream is up linked to the service provider’s satellite in DVB format. At the national head end, the video signals are pulled from satellites and encoded if necessary. The video stream is broken up into IP packets and sent into the provider’s network. The video streams are received by a local office, which delivers them out to the subscribers. Here local content like advertisements and video on demand can be added. Also the user authentication, channel change requests, billing, Video-on-Demand requests are done at the local office. At the user’s side, a set top box (STB) or a computer, connecting to the home DSL, fiber or wireless line, reassembles the IP packets into a coherent video stream and then decodes the contents [3].
A. Video on demand Video on Demand (VoD) make it possible for the users to choose and see video as well as the clip content. As far as the functionality of the video on Demand or VoD is concerned , the download as well as the streaming video on demand systems offer the user a huge subset of VCR functionality which includes fast forward , slow forward , pause , slow rewind , fast rewind, jump to previous frame or jump to future frame, and many other like options.
V.
WHERE IS THE DIFFERENCE ?
Cable TV architecture is designed to deliver all the broadcast content channels from their head-end locations simultaneously over a single transport feed with a defined bandwidth capability to large serving areas such as an entire city. On cable TV, the consumer is receiving the entire lineup of broadcast content channels all the time which requires huge amounts of bandwidth being delivered all the time into the home. IPTV delivers only the requested channel to the customer. Therefore, with IPTV the infrastructure needed to support huge amounts of bandwidth being delivered all the time is not needed.
B. Interactivity The television as we knew it (without a remote) was once an excellent example of interactivity. Then came sophisticated remote devices to television sets with far advanced features. After that, the focus shifted to high speed desktops, the World Wide Web, video conferencing, video chat, live web casts. The TV did not wish to lag behind and there came the advantages of IPTV. In IPTV, a new level of interactivity among Internet, voice, and video can be established.
As more and more advanced applications and services, requiring more bandwidth, are becoming available to the consumers, problems of legacy cable TV operators are also getting intensified. Their present single transport feeds will not have the needed bandwidth to deliver these services. They have two options either to grow their infrastructure to accommodate these greater bandwidth needs to meet consumer demands or converting their existing cable systems to IPTV based architecture systems. Either way, they are going to face huge amounts of capital investment in order to stay in the competition.
C. Convergence The IPTV based converged services implies interaction of existing services in a seamless manner to create new value added services. The examples can be On-Screen Caller ID, getting Caller ID on your TV and the ability to handle it and send it to voice mail, etc. Within businesses and institutions, IPTV eliminates the need to run a parallel infrastructure to deliver live and stored video services. D. Some more features • Users are able to select their TV programs with fast channel selection and short channel changing time.
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VI.
label switched paths (LSPs). Major applications of MPLS are traffic engineering and the virtual private network (VPN). Generalized MPLS (GMPLS) extends MPLS to add a signaling and routing control plane for devices in packet domain, time domain, wavelength domain, and fiber domain, providing end to-end provisioning of connections, resources, and QoS. GMPLS is a better protocol for broadband and IPTV services, controlling all the layers, including packet layer, time division multiplexing layer, lambda layer, and fiber layer [4].
IPTV ARHITECTURE OVERVIEW
Three building blocks of the IPTV network are: customer end, video headend and the transport network. A. Customer end On the customer side a set top box (STB) is the key player. It interfaces with the user terminal (e.g., a television, a PC, or a laptop) with DSL or cable wiring. STB is usually installed with middleware client software to obtain the program guide data, decode MPEG2, MPEG4 video data, and display on the screen.
Fig 2: IPTV architecture [3]
B. Video headend The video headend is composed of the following components: • Video encoder It encodes real-time video analog signals from a content provider or a live event location to a digital format based on a given video compression technology such as MPEG2/4. • Live video broadcast server This is in charge of reformatting and encapsulating video streams for ex. video steams with different formats from a video encoder. The server also interfaces the core network and transmits the video signal over the core network toward the access network. • VoD server This ‘video- on- demand’ server houses “on demand” content with streaming engines. It also has large storage capacity.
Fig 3: IPTV network.
• IP multicast Multicast delivers information to a group of destination stations. IP multicast sends voice, video, and data to multiple receivers using RTP/TCP/IP protocols, with a multicast address. There are three kinds of multicast delivery: dense multicast, sparse multicast, and source specific multicast. Dense multicast is to construct a tree for sending packets to the multicast users. A source node broadcasts to all routers and all nodes, which in turn send pruned packets if they do not want the multicast so that the routers do not send corresponding packets to these nodes or routers. Reverse-path forwarding is used for preventing loops. Sparse multicast does not depend on any particular unicast routing protocol and is to construct a tree for sending packets to the multicast users. If a node wants to join/prune a multicast group, it sends a join/prune message via Internet Group Management Protocol (IGMP) to a router, which forwards data packets to the multicast group. Join/prune messages are sent periodically to a group-specific rendezvous point (RP) by a designated router (DR) for each active group. Source-specific multicast delivers multicast packets originating in a specific source address to those that request them [4].
C. Transport networks Trasport network consists of two major parts namelycore networks and access networks. Here we give a brief introduction of GMPLS/MPLS and IP multicast as the core network technologies. MPLS/GMPLS MPLS provides better IP traffic engineering. Connectionless IP behaves more like connectionoriented so that a path between a source and a destination is pre-determined and labeled. The labels are used to establish end-to-end paths that are called
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• Session initiation and service control for IPTV services. • Selection of the relevant IPTV media control/delivery functions. • Credit control.
VII. IMS BASED IPTV Currently, IMS is widely accepted as one of the key platforms for future NGN service composition and delivery. In the ongoing ETSI TISPAN NGN R2, IMS also is used to support IPTV services. ETSI TISPAN extends its NGN R1 architecture to include non-IMS, as well as IMS-based IPTV concepts in its NGN R2 specifications [5]. In TISPAN NGN R2, several specifications address IPTV regarding service requirements and architectures with a nonIMS IPTV subsystem [3], as well as IMS-based IPTV. ETSI TISPAN IMS-based IPTV architecture is focused in this paper. IMS-based IPTV architecture specifies IPTV functions based on the IMS subsystem and enables reusing of IMS functionality and SIP-based service initiation and control mechanisms.
B. IPTV media functions IPTV media functions include MCFs and MDFs. Main tasks of MCFs are: • Selection of relevant MDFs. • Applying policy for the content distribution and management. • Mapping of content ID and content location to the corresponding MDF. • Storage management in the distribution and delivery networks. • Interaction with the UE (e.g., handling of videorecorder-like RTSP commands). • Collection of statistical information about service usages. MDFs are responsible mainly for the delivery of media (video, voice, and data) to the user equipment. Main tasks of MDFs are: • Handling media flow delivery. • Handling media flow delivery. • Processing, encoding, or transcoding (if required) media to various media formats. • Storage of most frequently accessed content or user specific content [5]. VIII. IMS CORE NETWORK The IMS core is used to forward the complete SIP signaling used in the IMS for session management. A number of Call Session Control Functions (CSCF) are introduced to establish a multimedia session between subscribers and to prepare delivery of the demanded services according to the session characteristics required by users. IMS core consist of these components:
Fig 4: IMS-based IPTV architecture for delivery of multimedia services [5]
As shown in Fig. 6, the user equipments can communicate with the IPTV application servers (including service control functions) over various interfaces for different purposes, namely, over a Gm interface via the IMS core for the session management purpose, directly over a Ut interface for the service profile configuration purpose, or over the Xa interface to interact with service selection functionalities.
A. HSS The Home Subscriber Server (HSS), or User Profile Server Function (UPSF), is a master user database which contains the subscription-related information (user profiles), performs authentication and authorization of the user, and can provide information about the user's physical location, ref fig 4.
A. IPTV service control functions IPTV SCFs handle IPTV-related requests and execute service and session control for all IPTV services. These functions are also responsible for interworking with the IMS core on the service control layer. Major functions of SCFs are: • Interaction with the IMS core and S-CSCFs to receive, validate, and perform IPTV service requests from users.
B. Proxy-CSCF (P-CSCF) First contact point within the IMS Core network subsystem is the Proxy Call State Control Function. C. Interrogating-CSCF (I-CSCF) I-CSCF queries the HSS using the diameter Cx interface to retrieve the user location and then routes the SIP request to its assigned S-CSCF, ref. fig. 4.
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D. Serving-CSCF (S-CSCF) The S-CSCF performs the session control services for the subscriber device. It is also a SIP server but performs Session control too. Since, it has no local storage of the user, it uses diameter Cx and Dx interfaces to the HSS to retrieve or send user profiles. IX.
The introduction of IPTV has made TV market an important area for telecom operators. For telecom operators, the standardization of IPTV solutions and the development of IPTV services in a unified service platform to reduce OPEX and CAPEX and to introduce new services and service features are extremely important. IMS seems to have been adopted by most operators as the unified service platform for NGNs. To support the evolving IPTV service, the broadband network must be able to scale in several dimensions, the most important of which are service penetration, network capacity, and service mix. By adding an IMS control layer to the broadband network infrastructure, operators can accelerate the introduction of new services, efficiently combine the TV service with communication services, and offer the service over multiple access networks [6].
ADVATAGES OF IMS BASED IPTV
By deploying and reusing existing IMS functionality to support IPTV services, there is a chance to optimize and reuse NGN concepts for following issues: • User subscription management, user profile centralization, and flexible user policy and service personalization. • Session management, routing, service trigger, numbering. • Quality of service (QoS) and bearer control. • Unified charging and billing. • Interaction with NGN service enablers (presence, messaging, group management, etc.) • Roam and nomadic support. X.
CONCLUSION
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CHALLENGES AND LIMITATIONS OF IPTV [4]
The way IPTV network handles data gives birth to a major problem. In an IP network, data is broken up into small packets and then sent off separately. At its final destination all the data packets are reassembled again. When video is put on an IP network that video is also broken up into small packets and sent from the source, the broadcaster, through the network, to eventually be reassembled into video that TV viewer gets to watch. Sometimes all packets do not arrive at the same rate or even in the correct order. This problem is known as jitter. However this problem can be solved by using a buffer.
[5]
[6] [7]
Successful deployment of IPTV services requires excellent QoS for video, voice, and data. QoS metrics for video include jitter, number of out-of-sequence packets, packet-loss probability, network fault probability, multicast join time, delay, and so on. QoS metrics for voice includes Mean Opinion Score (MOS), jitter, delay, voice packet loss rate, and so on. QoS metrics for IPTV services include channel availability, channel start time, channel change time, channel change failure rate, and so on. Before system deployment, accurate testing should be performed to test high-quality IPTV services for TV service, video, voice, as well as interactive service [4].
[8] [9] [10] [11]
[12]
Among the limitations of IPTV the most significant ones are packet loss and no support for HDTV. There is always a high chance of packet loss or delays. The service delivery can suffer significant clarity loss and the timing of the program delivery might get delayed from time to time.
[13]
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