Internet Protocol television (IPTV), also called TV over broadband, is the service delivery of television over Internet Protocol (IP) networks. Usually sold and run by a telecom provider, it consists of broadcast live television that is streamed over the Internet (multicast) — in contrast to delivery through traditional terrestrial, satellite, and cable transmission formats — as well as video on demand services for watching or replaying content (unicast).
IPTV broadcasts started gaining usage during the 2000s alongside the rising use of broadband-based internet connections. It is often provided bundled with internet access services by Internet service providers (ISPs) to subscribers and runs in a closed network. IPTV normally requires the use of a set-top box, which receives the encoded television content in the MPEG transport stream via IP multicast, and converts the packets to be watched on a TV set or other kind of display. It is distinct from over-the-top (OTT) services, which are based on a direct one-to-one transmission mechanism.
IPTV methods have been standardised by organisations such as ETSI. IPTV has found success in some regions: for example in Western Europe in 2015, pay IPTV users overtook pay satellite TV users. IPTV is also used for media delivery around corporate and private networks.
Definition Historically, many different definitions of IPTV have appeared, including elementary streams over IP networks, MPEG transport streams over IP networks and a number of proprietary systems. One official definition approved by the International Telecommunication Union focus group on IPTV (ITU-T FG IPTV) is:
IPTV is defined as multimedia services such as television/video/audio/text/graphics/data delivered over IP-based networks managed to provide the required level of quality of service and experience, security, interactivity and reliability.
Another definition of IPTV, relating to the telecommunications industry, is the one given by Alliance for Telecommunications Industry Solutions (ATIS) IPTV Exploratory Group in 2005:
IPTV is defined as the secure and reliable delivery to subscribers of entertainment video and related services. These services may include, for example, Live TV, Video On Demand (VOD) and Interactive TV (iTV). These services are delivered across an access agnostic, packet switched network that employs the IP protocol to transport the audio, video and control signals. In contrast to video over the public Internet, with IPTV deployments, network security and performance are tightly managed to ensure a superior entertainment experience, resulting in a compelling business environment for content providers, advertisers and customers alike.
History Up until the early 1990s, it was not a concept that a television programme could be squeezed into the limited telecommunication bandwidth of a copper telephone cable to provide a video-on-demand (VOD) television service of acceptable quality, as the required bandwidth of a digital television signal was around , which was 2,000 times greater than the bandwidth of a speech signal over a copper telephone wire. VOD services were only made possible as a result of two major technological developments: motion-compensated DCT video compression and asymmetric digital subscriber line (ADSL) data transmission. Motion-compensated DCT algorithms for video coding standards include the H.26x formats from 1988 onwards and the MPEG formats from 1991 onwards. Motion-compensated DCT video compression significantly reduced the amount of bandwidth required for a television signal, while at the same time ADSL increased the bandwidth of data that could be sent over a copper telephone wire. ADSL increased the bandwidth of a telephone line from around to , while DCT compression reduced the required bandwidth of a digital television signal from around down to about . The combination of DCT and ADSL technologies made it possible to practically implement VOD services at around bandwidth in the 1990s.
The term IPTV first appeared in 1995 with the founding of Precept Software by Judith Estrin and Bill Carrico. Precept developed an Internet video product named IP/TV. IP/TV was an Mbone compatible Windows and Unix-based application that transmitted single and multi-source audio and video traffic, ranging from low to DVD quality, using both unicast and IP multicast Real-time Transport Protocol (RTP) and Real time control protocol (RTCP). The software was written primarily by Steve Casner, Karl Auerbach, and Cha Chee Kuan. Precept was acquired by Cisco Systems in 1998. Cisco retains the IP/TV trademark.
Telecommunications company US West (later Qwest) launched an IPTV service called TeleChoice in Phoenix, Arizona in 1998 using VDSL technology, becoming the first company in the United States to provide digital television over telephone lines. The service was shut down in 2008.
Internet radio company AudioNet started the first continuous live webcasts with content from WFAA-TV in January 1998 and KCTU-LP on 10 January 1998.
Kingston Communications, a regional telecommunications operator in the UK, launched Kingston Interactive Television (KIT), an IPTV over digital subscriber line (DSL) service in September 1999. The operator added additional VOD service in October 2001 with Yes TV, a VOD content provider. Kingston was one of the first companies in the world to introduce IPTV and IP VOD over ADSL as a commercial service. The service became the reference for various changes to UK Government regulations and policy on IPTV. In 2006, the KIT service was discontinued, subscribers having declined from a peak of 10,000 to 4,000.KIT Kingston Interactive Television . Kitv.co.uk. Retrieved on 12 March 2014.
In 1999, NBTel (now known as Bell Aliant) was the first to commercially deploy Internet protocol television over DSL in Canada using the Alcatel 7350 DSLAM and middleware created by iMagic TV (owned by NBTel's parent company Bruncor). The service was marketed under the brand VibeVision in New Brunswick, and later expanded into Nova Scotia in early 2000 after the formation of Aliant. iMagic TV was later sold to Alcatel.
In 2005, Bredbandsbolaget launched its IPTV service as the first service provider in Sweden.
In 2010, CenturyLink – after acquiring Embarq (2009) and Qwest (2010) – entered five U.S. markets with an IPTV service called Prism. Later in 2010, Bell Canada (a major division of BCE) announced it would begin offering residential and business/commercial customers in Montreal, Quebec and Toronto, Ontario IPTV over a number of different modalities, including fibre to the home, fibre to the node and DSL.
Architecture
Elements An IPTV head-end is a place where live TV channels and AV sources are encoded, encrypted, and delivered as IP multicast streams. Meanwhile, a video on demand (VOD) platform stores on-demand video assets and serves them as IP unicast streams when a user requests them. Sometimes, the VOD platform is located within the IPTV head-end. An interactive portal allows users to navigate within the different IPTV services, such as the VOD catalogue. A delivery network is a packet-switched network that carries IP packets, including unicast and multicast streams. Endpoints refer to user equipment that can request, decode, and deliver IPTV streams for display to the user. This can include computers, mobile devices, and set-top boxes. At a residential IPTV user's home, the home TV gateway is the piece of equipment that terminates the access link from the delivery network. Lastly, the user set-top box is the piece of endpoint equipment that decodes and decrypts TV and VOD streams for display on the TV screen.
Architecture of a video server network Depending on the network architecture of the service provider, there are two main types of video server architecture that can be considered for IPTV deployment: centralised and distributed.
The centralised architecture model is a relatively simple and easy-to-manage solution. Because all media content is stored in centralised servers, it does not require a comprehensive content distribution system. Centralised architecture is generally good for a network that provides relatively small VOD service deployment, has adequate core and edge bandwidth or has an efficient content delivery network (CDN).
A distributed architecture has bandwidth usage advantages and inherent system management features that are essential for managing a larger server network. Distributed architecture requires intelligent and sophisticated content distribution technologies to augment effective delivery of multimedia content over the service provider's network.
Residential IPTV home networks In many cases, the residential gateway that provides connectivity with the Internet access network is not located close to the IPTV set-top box. This scenario becomes very common as service providers start to offer service packages with multiple set-top boxes per subscriber.
Networking technologies that take advantage of existing home wiring (such as power lines, phone lines or coaxial cables) or of Wireless hardware have become common solutions for this problem, although fragmentation in the wired home networking market has limited somewhat the growth in this market.HomeGrid Forum Blog – Why do we need a unified standard at all?
In December 2008, ITU-T adopted Recommendation G.hn (also known as G.9960), which is a next-generation home networking standard that specifies a common PHY/MAC that can operate over any home wiring (power lines, phone lines or coaxial cables).New global standard for fully networked home , ITU-T Press Release
Groups such as the Multimedia over Coax Alliance, HomePlug Powerline Alliance, Home Phoneline Networking Alliance, and Quasar Alliance (Plastic Optical Fibre)Quasar POF alliance each advocate their own technologies.
IMS-based architecture There is a growing standardisation effort on the use of the 3GPP IP Multimedia Subsystem (IMS) as an architecture for supporting IPTV services in telecommunications carrier networks. Both ITU-T and ETSI are working on so-called "IMS-based IPTV" standards (see e.g. ETSI TS 182 027). Carriers will be able to offer both voice and IPTV services over the same core infrastructure and the implementation of services combining conventional TV services with telephony features (e.g., caller ID on the TV screen) will become straightforward.
Protocols IPTV supports both live TV as well as stored video-on-demand. Playback requires a device connected to either a fixed or wireless IP network in the form of a standalone personal computer, smartphone, touch screen tablet, game console, connected TV or set-top box. Content is compressed by Video and audio codecs and then encapsulated in MPEG transport stream or Real-time Transport Protocol or other packets. IP multicasting allows for live data to be sent to multiple receivers using a single multicast group address.
In standards-based IPTV systems, the primary underlying protocols used are: Service-provider-based streaming: IGMP for subscribing to a live multicast stream (TV channel) and for changing from one live multicast stream to another (TV channel change). IP multicast operates within LANs (including VLANs) and across WANs also. IP multicast is usually routed in the network core by Protocol Independent Multicast (PIM), setting up correct distribution of multicast streams (TV channels) from their source all the way to the customers who wants to view them, duplicating received packets as needed. On-demand content uses a negotiated unicast connection. Real-time Transport Protocol (RTP) over User Datagram Protocol (UDP) or the lower overhead H.222 transport stream over Transmission Control Protocol (TCP) are generally the preferred methods of encapsulation.
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