IPTV ( INTERNET PROTOCOL TELEVISION)

Internet Protocol television (IPTV) is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats.

IPTV services may be classified into three main groups:

• live television, with or without interactivity related to the current TV show;
• time-shifted television: catch-up TV (replays a TV show that was broadcast hours or days ago), start-over TV (replays the current TV show from its beginning);
• video on demand (VOD): browse a catalog of videos, not related to TV programming.
IPTV is distinguished from Internet television by its on-going standardization process (e.g., European Telecommunications Standards Institute) and preferential deployment scenarios in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes or other customer-premises equipment.

Definition

Historically, many different definitions of IPTV have appeared, including elementary streams over IP networks, 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 more detailed definition of IPTV is the one given by Alliance for Telecommunications Industry Solutions (ATIS) IPTV Exploratory Group on 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."




In 1994, ABC's World News Now was the first television program to be broadcast over the Internet, using the CU-SeeMe videoconferencing software.
The term IPTV first appeared in 1995 with the founding of Precept Software by Judith Estrin and Bill Carrico. 

Elements

• TV head-end: where live TV channels are encoded, encrypted and delivered in the form of IP multicast streams.
• VOD platform: where on-demand video assets are stored and served when a user makes a request in the form of IP unicast stream.
• Interactive portal: allows the user to navigate within the different IPTV services, such as the VOD catalog.
• Delivery network: the packet switched network that carries IP packets (unicast and multicast).
• Home gateway: the piece of equipment at the user's home that terminates the access link from the delivery network.
• User's set-top box: the piece of equipment at the user's home that decodes and decrypt TV and VOD content and displays it on the TV screen.

Advantages

The Internet protocol-based platform offers significant advantages, including the ability to integrate television with other IP-based services like high speed Internet access and VoIP.

A switched IP network also allows for the delivery of significantly more content and functionality. In a typical TV or satellite network, using broadcast video technology, all the content constantly flows downstream to each customer, and the customer switches the content at the set-top box. The customer can select from as many choices as the telecomms, cable or satellite company can stuff into the “pipe” flowing into the home. A switched IP network works differently. Content remains in the network, and only the content the customer selects is sent into the customer’s home. That frees up bandwidth, and the customer’s choice is less restricted by the size of the “pipe” into the HOME This also implies that the customer's privacy could be compromised to a greater extent than is possible with traditional TV or satellite networks. It may also provide a means to hack into, or at least disrupt (see Denial of service) the private network.

Interactivity

An IP-based platform also allows significant opportunities to make the TV viewing experience more interactive and personalized. The supplier may, for example, include an interactive program guide that allows viewers to search for content by title or actor’s name, or a picture-in-picture functionality that allows them to “channel surf” without leaving the program they’re watching. Viewers may be able to look up a player’s stats while watching a sports game, or control the camera angle. They also may be able to access photos or music from their PC on their television, use a wireless phone to schedule a recording of their favorite show, or even adjust parental controls so their child can watch a documentary for a school report, while they’re away from home.

In order that there can take place an interaction between the receiver and the transmitter, a feedback channel is needed. Due to this, terrestrial, satellite, and cable networks for television do not allow interactivity. However, interactivity with those networks can be possible by combining TV networks with data networks such as the Internet or a mobile communication network.

Video-on-demand

IPTV technology is bringing video-on-demand (VoD) to television, which permits a customer to browse an online program or film catalog, to watch trailers and to then select a selected recording. The playout of the selected item starts nearly instantaneously on the customer's TV or PC.

Technically, when the customer selects the movie, a point-to-point unicast connection is set up between the customer's decoder (set-top box or PC) and the delivering streaming server. The signalling for the trick play functionality (pause, slow-motion, wind/rewind etc.) is assured by RTSP (Real Time Streaming Protocol).




 The most common codecs used for VoD are MPEG-2, MPEG-4 and VC-1.

In an attempt to avoid content piracy, the VoD content is usually encrypted. Whilst encryption of satellite and cable TV broadcasts is an old practice, with IPTV technology it can effectively be thought of as a form of Digital rights management. A film that is chosen, for example, may be playable for 24 hours following payment, after which time it becomes unavailable.

IPTV-based converged services

Another advantage of an IP-based network is the opportunity for integration and convergence. This opportunity is amplified when using IMS-based solutions. Converged services implies interaction of existing services in a seamless manner to create new value added services. One example is on-screen Caller ID, getting Caller ID on a TV and the ability to handle it (send it to voice mail, etc.). IP-based services will help to enable efforts to provide consumers anytime-anywhere access to content over their televisions, PCs and cell phones, and to integrate services and content to tie them together. Within businesses and institutions, IPTV eliminates the need to run a parallel infrastructure to deliver live and stored video services.

Limitations

IPTVIPTV is sensitive to packet loss and delays if the streamed data is unreliable. IPTV has strict minimum speed requirements in order to facilitate the right number of frames per second to deliver moving pictures. This means that the limited connection speed and bandwidth available for a large IPTV customer base can reduce the service quality delivered.

Although a few countries have very high-speed broadband-enabled populations, such as South Korea with 6 million homes benefiting from a minimum connection speed of 100 Mbit/s, in other countries (such as the UK) legacy networks struggle to provide 3–5 Mbit/s and so simultaneous provision to the home of TV channels, VOIP and Internet access may not be viable. The last-mile delivery for IPTV usually has a bandwidth restriction that only allows a small number of simultaneous TV channel streams – typically from one to three – to be delivered.

Streaming IPTV across wireless links within the home has proved troublesome; not due to bandwidth limitations as many assume, but due to issues with multipath and reflections of the RF signal carrying the IP data packets. An IPTV stream is sensitive to packets arriving at the right time and in the right order. Improvements in wireless technology are now starting to provide equipment to solve the problem.

Due to the limitations of wireless, most IPTV service providers today use wired home networking technologies instead of wireless technologies like 802.11. Service providers such as AT&T (which makes extensive use of wireline home networking as part of its U-Verse IPTV service) have expressed support for the work done in this direction by ITU-T, which has 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).

Latency

The latency inherent in the use of satellite Internet is often held up as reason why satellites cannot be successfully used for IPTV, but in practice latency is not an important factor for IPTV. An IPTV service does not require real-time transmission, as is the case with telephony or videoconferencing services.