Sunday, October 20, 2013

1. Introduction

In the 21st century, the access with broadband internet and downstream data rates of several Megabit per second (Mbit/s) is making a steady progress. With the increasing number of households are getting used to video streaming and download, use of the Internet Protocol (IP) to enable interactive retrieval of video content from the Web. This type of IP based television service is known as WebTV. However WebTV does not provide a guaranteed quality of service (QoS). Therefore now the telecommunication companies are making an attempt to overcome the deficiencies of WebTV and launched the so-called IPTV.

1.1 What is IPTV
Internet Protocol Television (IPTV) is a system where a digital television service is delivered over Internet Protocol network. Werner describes that “IPTV is not a welldefined term and may be a source or ambiguity and sometimes confusion”.
IPTV works on the TV with a set-top box that accesses channels, subscription services, on demand and other interactive multimedia services over a secure, end-to-end operator managed broadband IP data network with desired QoS to the public with a broadband Internet connection.

2. Current IPTV and Its Evolution

2.1 IPTV Deployment
IPTV is a system of delivering television content to consumers over the infrastructure of the Internet. With the proliferation of broadband networks set up by telephone companies to offer broadband Internet to consumers, IPTV has overcome the problem of having limited bandwidth that was once a major barrier to deployment.
Currently there are two different ways consumers can get IPTV. They can buy a "set topbox" which will convert an IPTV signal and play it on their television. The other option is to watch on a PC. Many IPTV service providers also offer voice and data capabilities with the IPTV service, making it a true "triple play" use of the broadband network. In the market of broadband applications IPTV is a major upset. With the advent of IPTV, many cable television companies are being expelled from the market of providing low cost television, data and voice broadband applications to consumers.
Business applications are also in development. Services such as streaming video are widely available on IPTV due to the scalability of the medium. The categories within IPTV are still gel, but possibilities are still wide open as to which of the many versions of IPTV will become standard. Companies are in the initial struggle to become leaders of the market, but at this point it is anyone's game. There is no doubt that IPTV is the next generation for television content, but it has yet to be determined which companies will be the benefactors of the innovations that are now taking place.

3. IPTV Building Blocks

The home gateway has to have powerful processing power and enough network bandwidth to provide networking service and to cope with various customers. In order for a system operator to deliver IPTV, it would require encoding, broadcast, and do the appropriate management before the end user can connect their set-top-box.
 
IPTV Basic Building Blocks

4. IPTV Architecture


A typical IPTV architecture is comprised of the following functional blocks:
• Super head-end: Where most of the IPTV channels enter the network from national broadcasters
• Core network: Usually an IP/MPLS network transporting traffic to the access network
• Access network: Distributes the IPTV streams to the DSLAMs
• Regional head-end: Where local content is added to the network
• Customer premises: Where the IPTV stream is terminated and viewed

Typical IPTV System Architecture

For a very large IPTV delivery system, there is often a hierarchy of facilities constructed to deliver video signals across a large expanse of territory. One Super Head-end can serve millions of customers by processing the video channels that are common to all subscribers across the serving area. A Video Serving Office is located in each region as required to handle local programming and channels specific to a single city or geographic area. The Remote Terminal can serve as a Regional Head-end that contains the equipment needed to actually deliver the programming to customers in local area.

Broadcast information coming from an antenna or a satellite dish at the Super Headend is mainly distributed using MPEG-2 multi-program transport stream (MPTS) to the video service node. The distribution of the actual SDTV or HDTV channel content is performed using various devices on the access network, such as digital subscriber line access multiplexers (DSLAM) and other technologies like fibre-to-the-home (FTTH) can be used to interface with the user’s STB. For IPTV, each channel is distributed using a multicast IP address.

5. IPTV Networking Technologies

IPTV technology is part of a new breed of services designed to facilitate access to video entertainment. It provides access to digital TV over the IP transport medium from a head-end device to the end user’s TV set-top box (STB). Most service providers use a dedicated transport network to support IPTV.

5.1 IP Distribution to the STB via DVB IPI
DVB has had a technical ad-hoc committee (TM-IPI) dedicated to IP distribution to the STB since 2000. It has a responsibility to provide a standard for the IP interface connected to the STB. The special feature about this technology in contract to the other standard bodies and traditional broadcast methodology is that it starts at the STB and then works to outwards.
The standards bodies of TM-IPI are shown in figure below.
 
IPTV related activities of selected standardisation bodies
  

6. IPTV Standards and Solutions

Setting standards for IPTV would be difficult at best. There are multiple areas to cover, as IPTV is very broad subject, and the medium was not intended to transport audio and video when it was created. Moreover, some specific features of this medium allow some services while outdating some of the former schemes based on broadcast.
Standardization is important in the telecommunications industry. Especially when talking about such a complex and large system as IPTV. So it requires many standards for the user’s vote to be securely recorded when pressing the red button on the remote control. The main standards body for IPTV has emerged to be ETSI (European Telecommunications Standardization Institute), through the branch that develops standards for the “next generation networks”, which many telecom operators are deploying.
Table 1: The standards organisations driving IPTV


7.Set-top Boxes

An IP set-top box is a dedicated computing device that serves as an interface between a television set and a broadband network. In addition to decoding and rendering broadcast live TV signals, a set-top box provides functionality that includes video-on-demand (VOD), electronic program guide (EPG), digital rights management (DRM), and a variety of interactive and multimedia services. Set-top boxes can support additional features such as Web browsing, e-mail and viewing e-mail attachments, advanced multimedia codecs, home networking and PC connectivity including playback and rendering of content stored on the PC (photos, music, and personal videos), gateway functionality, instant messaging (IM), and real-time voice over IP (VoIP). These types of advanced functionality are in demand by end-users, enable incremental network operator service opportunities, and allow set-top box manufacturers to easily offer a large range of differentiated devices.
Also to provide secure delivery of satellite data in IPTV systems, service providers charge subscribing fee by scrambling the program in conditional access system using control words. At the receiver end, smart card is used to decrypt the control words and transfer them back to set-top box to descramble the scrambled program. Therefore, secure communication between set-top box and smart card is closely related with the benefit of service providers and the legal rights of users.
Current set-top box development is driven by service provider requirements and customer demand for new features. Priorities for service providers include the capacity to deploy, using minimal capital expenditures, new revenue-generating services and multimedia and entertainment-oriented applications on a set-top box to meet changing customer requirements over time. Service providers also need to ensure that copyrighted content is protected from unauthorized distribution. To accommodate these expectations, the set-top box operating system platform must be extensible and remotely upgradeable, and include both rich multimedia technologies and fundamental security features, such as access control.

8. Control Technologies and solutions

8.1 Encryption of video and audio data
Encryption provides secure connections and protects data from unexpected modification by other outsiders. Encryption is the first step taking the raw video and audio and encoding it in a systematic way so as to become unreadable to anyone without the necessary key. Decryption is the reverse process which is taking the key and the encrypted file and decoding it to produce an exact copy of the original signal. The decoder needs to have exactly the same key for decryption that the encoder used for encryption.
Many different encryption systems have been designed that embody these core traits.
Some of the more common ones are listed below.

Smart Cards:
This is one of the common forms of key distribution for STBs. These cards are called “smart” because they incorporate a processor and memory that can be used by a variety of applications.
Each television channel has a unique decryption key that is created when the content is prepared for broadcast. When an authorized viewer wants to watch scrambled content, the viewer’s device sends a request to a central server. This server checks to see if the viewer is authorized to view the content. If so, the server locates the correct descrambling key for the desired content and encrypts it using the appropriate public key that corresponds to the user’s smart card. Then the server sends the encrypted descrambling key to the viewers’ device over the communication path. When it arrives, the encrypted key is fed into the smart card, and the smart card performs the decryption process. Then viewers’ STB can use the decrypted descrambling key to process the incoming signal and play the content for the viewer.

Watermarking:
Watermarking is the process of inserting data into video or audio streams to track usage or rove ownership of the streams. Digital watermarking capabilities that detect piracy to the guilty individual's set-top box.
Watermarking helps in rights enforcement when a unique watermark is created for each individual user. Individual watermarks can serve as a deterrent to unauthorized use of the content, since any misappropriate can be traced back to the specific source of the leak.

8.2 Digital Rights Management System
A Digital Rights Management (DRM) System is designed to protect the property rights of a content owner. This involves some form of encryption or scrambling that renders the content unwatchable without the appropriate key. The key is usually a numeric value that controls the operation of a descrambler or decryption device.

The DRM system also needs to be able to securely deliver the appropriate keys to authorized viewers’ STBs. With these keys, the STBs will be able to make sense of the incoming stream and display it properly. Key distribution needs to be secure to prevent unauthorized viewers from obtaining the keys either by deliberate action or unintentionally.

9. Home Networking

9.1 The importance of the home network connection
Today, people’s homes are becoming a place where members of the family use an increasingly large variety of different media devices. So the home-networking has been used for communication between digital divices deployed in home, usually iPods, mobile phones, DVD recorders, personal computers, gaming consoles, storage devices and many others. Home-network system allows users to share content regardless of where it originated or stored, control the delivery and access, allocate the bandwidth and integrate the new devices automatically.
The important function of Home-networking is that it uses IP to share the files and streams through the cable tv or Digital Subscriber Line (DSL) provider. But generally uses may like to replace their old coaxial cables with more modern Wireless Local Area Networks (WLAN), Power-Line Communications (PLC) or even Giga-bit Ethernet cabling.
 
Figure: Typical Home-Networking scenario