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IPTV (Internet Protocol Television)
   

IPTV (Internet Protocol Television) Network ArchitectureIPTV (Internet Protocol Television) is a system where a digital television service is delivered using Internet Protocol over a network infrastructure, which may include delivery by a broadband connection. A general definition of IPTV is television content that, instead of being delivered through traditional broadcast and cable formats, is received by the viewer through the technologies used for computer networks.

For residential users, IPTV is often provided in conjunction with Video on Demand and may be bundled with Internet services such as Web access and VoIP. The commercial bundling of IPTV, VoIP and Internet access is referred to as "Triple Play" service (adding mobility is called "Quadruple Play"). IPTV is typically supplied by a service provider using a closed network infrastructure. This closed network approach is in competition with the delivery of TV content over the public Internet, called Internet Television. In businesses, IPTV may be used to deliver television content over corporate LANs.

   
 

IPTV (Internet Protocol Television) Network Architecture


 

 
Architecture of IPTV

Architecture of a Video Server Network

Depending on the network architecture of the Service Provider, there are two main types of Video Server architectures that can be considered for IPTV deployment, Centralized, and Distributed.

The Centralized Architecture model is a relatively simple and easy to manage solution. For example, as all contents are stored in Centralized servers, it does not require a comprehensive content distribution system. Centralized Architecture is generally good for a network that provides relatively small VOD service deployment, has adequate core and edge bandwidth and has an efficient Content Delivery Network (CDN).

A Distributed Architecture is just as scalable as the Centralized model, however it has bandwidth usage advantages and inherent system management features that are essential for managing a larger server network. Operators who plan to deploy a relatively large system should therefore consider implementing a Distributed Architecture model right from the start. Distributed Architecture requires intelligent and sophisticated content distribution technologies to augment effective delivery of multimedia contents over service provider's network.

Key Areas of an End-to-End IPTV Technology Solution

When considering deploying a telco IPTV service, understanding the technical implications of delivering the solution should be of paramount importance. Within the overall technical parameters of an IPTV service rollout, there are four key areas that need to be addressed to ensure a robust and scalable service delivery: content distribution, middleware, transport infrastructure and customer premise equipment.

The content distribution module contains live encoding platforms, video file repository and IPTV video servers which are the key elements enabling video feeds for an IPTV service.

In general, content distribution (in the headend), processing and adaptation are all part of the functions of a TV headend.

While the live video encoder and IPTV video server are conceptually considered to be part of the TV [headend], they not necessarily need to be placed at the same physical location. Multicast video sources are usually located at the top level of the core network for better bandwidth efficiency, whereas unicast IPTV video sources are commonly installed at the local PoP level to minimize core bandwidth usage.

IMS architecture for IPTV

There is a growing standardization effort on the use of the 3GPP IP Multimedia Subsystem (IMS) as an architecture for supporting IPTV services in carriers networks. Both ITU-T and ETSI are working on so-called "IMS-based IPTV" standards (see e.g ETSI TS 182 027[12]). The benefits of this approach are obvious. 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 straigthforward.


 

   
Protocols

IPTV covers both live TV (multicasting) as well as stored video (Video on Demand VOD). The playback of IPTV requires either a personal computer or a set-top box connected to a TV. Video content is typically compressed using either a MPEG-2 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. IP Multicast is a method in which information can be sent to multiple computers at the same time. The newly released (MPEG-4) H.264 codec is increasingly used to replace the older MPEG-2 codec.

In standards-based IPTV systems, the primary underlying protocols used are:

• Live TV uses IGMP version 2 for connecting to a multicast stream (TV channel) and for changing from one multicast stream to another (TV channel change).
• VOD is using the Real Time Streaming Protocol (RTSP).
• NPVR (network-based Personal Video Recorder)

Network Personal Video Recording is a consumer service where real-time broadcast television is captured in the network on a server allowing the end user to access the recorded programs on the schedule of their choice, rather than being tied to the broadcast schedule. The NPVR system provides time-shifted viewing of broadcast programs, allowing subscribers to record and watch programs at their convenience, without the requirement of a truly personal PVR device. It could be compared as a "PVR that is built into the network" -- however that would be slightly misleading unless the word "Personal" is, of course, changed to "Public" for this context.

Subscribers can choose from the programmes available in the network-based library, when they want, without needing yet another device or remote control. However, many people would still prefer to have their own PVR device, as it would allow them to choose exactly what they want to record. This bypasses the strict copyright and licensing regulations, as well as other limitations, that often prevent the network itself from providing "on demand" access to certain programmes.

Currently, the only alternatives to IPTV are traditional TV distribution technologies such as terrestrial, satellite and cable. However, cable can be upgraded to two-way capability and can thus also carry IPTV.


 
   
Advantages

The IP-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 telecoms, 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 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.

Note that this is all possible, to some degree, with existing digital terrestrial, satellite and cable networks in tandem with modern set top boxes.


VoD

VoD stands for Video on Demand. VoD permits a customer to browse an online programme or film catalogue, to watch trailers and to then select a selected recording for playback. The playout of the selected movie 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 (SetTopBox 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 good example is On-Screen Caller ID, getting Caller ID on your 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

Because IPTV requires real-time data transmission and uses the Internet Protocol, it is sensitive to packet loss and delays if the streamed data is unreliable. If the IPTV connection is not fast enough, picture break-up or loss may occur. This problem has proved particularly troublesome when attempting to stream IPTV across wireless links. Improvements in wireless technology are now starting to provide equipment to solve the problem. Because of its high latency Satellite Internet Access is not ideal for IPTV. This is because the data has to travel so far to reach the satellite and then come back to earth. A cable, DSL, or FiOS internet connection is much more reliable for IPTV.


 
   
Vendors

A small number of companies supply most current IPTV systems. Some, such as Imagenio, were formed by telecom operators themselves, to minimise external costs, a tactic also used by PCCW of Hong Kong. Some major telecoms vendors are also active in this space, notably Alcatel-Lucent (sometimes working with Imagenio), Ericsson (notably since acquiring Tandberg Television), NEC, Thomson, Logic Innovations, and ZTE, as are some IT houses, led by Microsoft. California-based UTStarcom, Inc. and Tennessee-based Worley Consulting also offer end-to-end networking infrastructure for IPTV-based services, and Hong Kong-based BNS Ltd. provides turnkey open platform IPTV technology solutions. Global sales of IPTV systems exceeded 2 billion USD in 2007.

Many of these IPTV solution vendors are participating in the biennial Global MSF Interoperability 2008 (GMI) event which is coordinated by the MultiService Forum (MSF) at 5 sites worldwide and runs from 20- to 31-October 2008. Test equipment vendors including Empirix, Ixia, Mu Dynamics and Spirent are joining solution vendors such as the companies listed above in one of the largest IPTV proving grounds.
 
   

Read More:

  • 'IPTV Deployment Challenges and Opportunities', Anurag Srivastava & Swarup Acharya, Bell Laboratories, Lucent Technologies, IEEE Tutorial

    IEEE Tutorial Summary
    IPTV is generating huge interest in the telecom industry lately. By offering video over their access infrastructure, Telcos hope to match the voice, video and data ("triple-play") offering of Cable providers. However, unlike Cable TV systems that are typically analog broadcast transmissions, IPTV uses IP-multicast over point-to-point hybrid Fiber/DSL infrastructure that while enabling more efficient networks, is also causing Telcos growing pains in field deployments.
    In this tutorial, we will provide an overview of the network architectures and will highlight the various tradeoffs (e.g., channel change latency vis-a-vis compression technology). We will focus on hardware and software technologies from the service provider core to the home --- multicast transport, DSL technologies, MPEG standards and home-networking requirements such as the IPTV set-top box. Finally, we will also review the regulatory issues faced by Telcos, and describe the various lifestyle services such as "CallerId-on-TV" and converged voice-video applications that provides IPTV its cutting-edge differentiation.
  • Presentation Slides for IPTV Deployment Challenges and Opportunities
   
   
 

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