Symbiosis Institute of Telecom Management

Next Generation Networks

Introduction:

With the Internet now deeply rooted across modern life and broadband penetration continuing its steady ascent, the information and communications technology (ICT) industry continues its transformation and evolution to converged next-generation networks (NGN)). The term “convergence” is being used to refer to the advanced integration of communications and computing functionalities, in particular the ability to offer voice, data, video(triple play) seamlessly over single or multiple infrastructures and platforms -- as well as the capability to access such services at any time and with an ever-expanding array of network agnostic and “aware” devices Next generation networks have finally identified as network collection emerging the following common characteristics:

• Convergence of various data communication types over the IP, i.e. data, multimedia, voice.
• Fixed, wireless and mobile network convergence
• Access to a common set of services that can be provided over multiple access network types (ADSL, UTRAN, WiFi, WiMAX, etc) with features like user handover and roaming.
• IP-based core transport networks,
• Possibility for using any terminal type (PC, PDA, mobile telephone, set-top boxes, etc),
• User-driven service creation environments,
• Common set of services, admission policies, authentication type regardless of the user connection type to the network.

NGN Architecture

The basic premise for NGN is an architecture on several independent levels. The connection of subscribers and terminals to the NGN can be achieved with various access technologies with compatible information and transmission which calls for Gateways. The core network of the NGN is an IP network which is a standardized transport platform consisting of various IP routers and switches. Standard and value-added services can then be provided via the service management level.

The convergence allows a transition from a vertical to a horizontal service integration. In vertical network structures, services (e.g. phone services, TV services) can only be received with suitable networks and the relevant end devices. With a horizontal approach, users in future will be given the possibility of using the desired services – regardless of the platform and the technology – with an end device.

In NGN networks, real-time conversational (e.g. video-telephony/conferencing) and non-conversational (e.g. video-on demand, instant messaging) multimedia services will play a prominent role in their success on the market. Therefore it is important that the security, customer experience and QoS perceived by paying users is much greater than that of free Internet services. To satisfy those requirements NGN funding members have devised two main mechanisms, one for providing control over the user sessions and a second one for enforcing the QoS settings of the user across the end-to-end communication path using the SIP protocol, through which the user can be identified, authenticated and charged by the network on the basis of a single user identity (IMS Personal Identity-IMPI).

Business Implications of NGN

It is certainly true that we are moving from Time Division Multiplex (TDM)-based, circuit switched networks to packet-, cell-, and frame-based networks. The major benefits of NGN can be listed as follows:-
1. Heterogeneity of the Telecommunications Infrastructure.
The growing number of services with different has increased the complexity of the overall infrastructure. The problems of interoperability between the various systems are becoming more serious. Maintaining these platforms involves high OPEX for the network operators. NGN provides an obvious solution to this problem.
2. Falling Call Sales.
Increasing losses on the domestic fixed-network market are therefore forcing the operators to develop new strategies to secure their future and to boost their profitability. No further growth can be expected through the revenue obtained from call sales alone.
3. Cost reduction:With NGN, the established network operators plan to develop a sustainable infrastructure that will remain competitive in a convergent environment. The primary focus will be on the potential for cost savings
4. New Sources of Income:Established network operators see the possibility of new income as another motivation for promoting NGN. More and more innovations with new sales opportunities are expected in the field of value-added services with enhanced QoS.
5. Ease of Maintainence: IP-based networks are likely to be simpler and easier to operate and maintain as compared to the existing legacy networks and provide operators with sufficient flexibility to reduce both OPEX and CAPEX.
6. Converged IP Core transport: Integration of their disparate networks towards IP/MPLS based transport core for superior control and OPEX reduction. Migration from TDM to IP and Fixed Mobile Convergence are also motivating factors for the carriers to reduce OPEX.

Multi Protocol Label Switching (MPLS)

Multiprotocol Label Switching (MPLS)　is a mechanism in high-performance telecommunication layer which directs and carries data from one network node to the next. MPLS operates at an OSI Model layer that is generally considered to lie between traditional definitions of Layer 2 (Data Link Layer ) and Layer 3 (Network Layer), and thus is often referred to as a "Layer 2.5" protocol.

WORKING :

Labeling packets are the main concept behind MPLS. These short, fixed-length labels carry the information that tells each switching node (router) how to process and forward the packets, from source to destination. As each node forwards the packet, it swaps the current label for the appropriate label to route the packet to the next node. This mechanism enables very-high-speed switching of the packets through the core MPLS network. MPLS predetermines the path data takes across a network and encodes that information into a label that the network’s routers understand.

MPLS routing

MPLS networks establish Label-Switched Paths (LSPs) for data crossing the network. An LSP is defined by a sequence of labels assigned to nodes on the packet’s path from source to destination.

As the network is established and signaled, each MPLS router builds a Label Information Base (LIB)—a table that specifies how to forward a packet. This table associates each label with its corresponding FEC and the outbound port to forward the packet to. This LIB is typically established in addition to the routing table and Forwarding Information Base (FIB) that traditional routers maintain.

Signaling and label distribution

Connections are signaled and labels are distributed among nodes in an MPLS network using one of several signaling protocols, including Label Distribution Protocol (LDP) and Resource reservation Protocol with Tunneling Extensions (RSVPTE). Alternatively, label assignment can be piggybacked onto existing IP routing protocols such as BGP. The most commonly used MPLS signaling protocol is LDP. LDP defines a set of procedures used by MPLS routers to exchange label and stream mapping information. It is used to establish LSPs, mapping routing information directly to Layer 2 switched paths. It is also commonly used to signal at the edge of the MPLS network — the critical point where non-MPLS traffic enters. Such signaling is required when establishing MPLS VPNs, for example.

Data Flow in MPLS Network


Figure shows a typical MPLS network and its associated elements. The central cloud represents the MPLS network itself. All data traffic within this cloud is MPLS labeled. All traffic between the cloud and the customer networks is not MPLS labeled (IP for example). The customer owned Customer Edge (CE) routers interface with the Provider Edge (PE) routers (also called Label Edge Routers, or LERs) owned by the service provider. At the ingress (incoming) side of the MPLS network, PE routers add MPLS labels to packets. At the egress (outgoing) side of the MPLS network, the PE routers remove the labels. Within the MPLS cloud, P (Provider) routers (also called Label Switching Routers , or LSRs), switch traffic hop-by-hop based on the MPLS labels. To demonstrate an MPLS network in operation, we will follow the flow of data through the network in Figure 2:

1. Before traffic is forwarded on the MPLS network, the PE routers first establish LSPs through the MPLS network to remote PE routers.

2. Non-MPLS traffic (Frame Relay, ATM, Ethernet, etc.) is sent from a customer network, through its CE router, to the ingress PE router operating at the edge of the provider’s MPLS network.

3. The PE router performs a lookup on information in the packet to associate it with a FEC, then adds the appropriate MPLS label(s) to the packet.

4. The packet proceeds along its LSP, with each intermediary P router swapping labels as specified by the information in its LIB to direct the packet to the next hop.

5. At the egress PE, the last MPLS label is removed and the packet is forwarded by traditional routing mechanisms.

6. The packet proceeds to the destination CE and into the customer’s network.

 　

DIRECT TO HOME(DTH)

Direct to Home is a term used to refer to satellite television broadcasts intended for home reception, also referred to more broadly as Direct broadcast satellite (DBS) signals. The expression direct-to-home or DTH was, initially, meant to distinguish the transmissions directly intended for home viewers from cable television distribution services that sometimes carried on the same satellite. Direct broadcast satellite, (DBS) also known as "Direct-To-Home" is a relatively recent development in the world of television distribution. “Direct broadcast satellite” can either refer to the communications satellites themselves that deliver DBS service or the actual television service. DBS systems are commonly referred to as "mini-dish" systems. DBS uses the upper portion of the K_u band, as well as portions of the K_a band. Modified DBS systems can also run on C-band satellites and have been used by some networks in the past to get around legislation by some countries against reception of K_u-band transmissions.

Technical aspect of DTH

 There are five major components involved in a direct to home (DTH) satellite system: the programming source, the broadcast centre, the satellite, the satellite dish and the receiver.

Programming Source 

Programming sources are simply the channels that provide programming for broadcast. The provider (the DTH platform) doesn’t create original programming itself; it pays other companies (HBO, for example, or ESPN or STAR TV or Sahara etc.) for the right to broadcast their content via satellite. In this way, the provider is kind of a broker between the viewer and the actual programming sources. The broadcast centre is the central hub of the system. At the broadcast centre or the Playout & Uplink location, the television provider receives signals from various programming sources, compresses using digital compression, if necessary scrambles it and beams a broadcast signal to the satellite being used by it. The satellites receive the signals from the broadcast station and rebroadcast them to the ground. The viewer’s dish picks up the signal from the satellite (or multiple satellites in the same part of the sky) and passes it on to the receiver in the viewer’s house. The receiver processes the signal and passes it on to a standard television. Lets look at each step in the process in greater detail. Satellite TV providers get programming from two major sources: International turnaround channels (such as HBO, ESPN and CNN, STAR TV, SET, B4U etc) and various local channels (SaB TV, Sahara TV, Doordarshan, etc).

THE BROADCAST CENTER

The broadcast centre converts all of this programming into a high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity of data — about 270  Megabits per second (Mbps) for each channel. In order to transmit the signal from there, the broadcast centre has to compress it. Otherwise, it would be too big for the satellite to handle. The providers use the MPEG-2 compressed video format. With MPEG-2 compression, the provider can reduce the 270-Mbps stream to about 3 or 10 Mbps (depending on the type of programming). This is the crucial step that has made DTH service a success. With digital compression, a typical satellite can transmit about 200 channels. Without digital compression, it can transmit about 30 channels. At the broadcast centre, the high-quality digital stream of video goes through an MPEG-2 encoder, which converts the programming to MPEG-2 video of the correct size and format for the satellite receiver in your house.

ENCRYPTION & TRANSMISION

After the video is compressed, the provider needs to encrypt it in order to keep people from accessing it for free. Encryption scrambles the digital data in such a way that it can only be decrypted (converted back into usable data) if the receiver has the correct decoding satellite receiver with decryption algorithm and security keys. Once the signal is compressed and encrypted, the broadcast centre beams it directly to one of its satellites. The satellite picks up the signal, amplifies it and beams it back to Earth, where viewers can pick it up.

 THE DISH

A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam. The dish on the receiving end can’t transmit information; it can only receive it. The receiving dish works in the exact opposite way of the transmitter. When a beam hits the curved dish, the parabola shape reflects the radio signal inward onto a particular point, just like a concave mirror focuses light onto a particular point. In this case, the point is the dish’s feed horn, which passes the signal onto the receiving equipment. In an ideal setup, there aren’t any major obstacles between the satellite and the dish, so the dish receives a clear signal. In some systems, the dish needs to pick up signals from two or more satellites at the same time. The satellites may be close enough together that a regular dish with a single horn can pick up signals from both. This compromises quality somewhat, because the dish isn’t aimed directly at one or more of the satellites.

 THE RECEIVER

The end component in the entire satellite TV system is the receiver. The receiver has four essential jobs: It de-scrambles the encrypted signal. In order to unlock the signal, the receiver needs the proper decoder chip for that programming package. The provider can communicate with the chip, via the satellite signal, to make necessary adjustments to its decoding programs. The provider may occasionally send signals that disrupt illegal de-scramblers, as an electronic counter measure (ECM) against illegal users.

It takes the digital MPEG-2 signal and converts it into an analog format that a standard television can recognize. Since the receiver spits out only one channel at a time, you can’t tape one program and watch another. You also can’t watch two different programs on two TVs hooked up to the same receiver. In order to do these things, which are standard on conventional cable, you need to buy an additional receiver. Some receivers have a number of other features as well. They pick up a programming schedule signal from the provider and present this information in an onscreen programming guide.

                                                                                                                 BY  -   KUMAR KAMAL

SUBMARINE CABLE

A submarine communications cable is laid beneath the sea to carry telecommunication between countries. The submarine cables were used initially for telegraphic transmission. It was later used for telephone communication however now it is used to transfer data. Modern submarine optical fiber cable is today the backbone of all internets. The following table shows the details of International communication traffic carried by satellite and submarine cables:

Year	Satellites	Submarine Cables
1990	80%	20%
1995	44%	56%
2006	5%	95%
2010	1-2%	98-99%

In the very initial stages, Coaxial cable was used in the core of submarine cables. The first optical fiber cable was TAT-8 which went into operation in 1988; it comprised of two operational pairs and one back up pair. Earlier optic fiber cables had a single point to point connection. With the growth in submarine branching units, a single cable was able to serve more than one destination system. However modern cable systems comprise of self healing ring which helps it to improve its superfluous criterion. The more recent development in the self healing ring was the introduction of mesh networks. In this type of network fast switching devices are used which makes it possible to transfer services apathetic to the higher level protocols. The total carrying capacity of sub marine cables is terabits per second.

A cable landing point is the location where a submarine or other underwater cable makes landfall. These points are usually carefully chosen to be in areas that have little marine traffic, without strong currents, so that the chances of cable being damaged can be reduced.

Dense Wave Division Multiplexing (DWDM) ,which enhances the capacity without adding fibers, is used in submarine cables. At the other end, DWDM demultiplexers capable of distinguishing each wavelength without crosstalk. For maintaining the level of the communication signals EDFA are used. Submarine cables can be broken by fishing trawlers, anchors, earthquakes, undersea avalanches, and even shark bites. The average incidence of cable faults was 3.7 per 1,000 km per year from 1959 to 1979. That rate was reduced to 0.44 faults per 1,000 km per year after 1985, due to widespread burial of cable starting in 1980. Based on surveying breaks the repair ships with several types of grapple is used.

The submarine cable is having all the advantages of optical fibre. Moreover, it has following benefits over satellite communication:

• Cost effective in long term
• Fulfills increased demand of bandwidth
• Better security
• More dependable installation
• Better repair practices

BUSINESS ASPECT

Sub marine cable business is a booming industry with submarine cable business fast approaching revenue peaks that happened during the Internet boom in early 2000, according to Alcatel Lucent a market leader in sub marine cable suppliers. The rapid growth which is currently being witnessed is mainly driven by investments in up-and-coming markets and high demands for services including mobile broadband, movement towards bigger IP based domains, SAT, teleports and long distance calls. There is a competition amongst the telecom operators and suppliers around the globe to install new submarine cable capacity to enhance data links to regions like sub-Saharan Africa and Asia, that includes south and east Asia. Thus there is a clear shift in focus from Europe to Asia and Africa as far as submarine cable business is concerned.

In Asian region, specifically India, leading Telco Bharti Airtel is expanding its submarine cable offerings globally to target business opportunities in over 100 countries by 2013, Reliance FLAG is working on NGN System – 2 connecting India and Kenya with potential extension to South Africa.

Submarine cable projects in African and sub-Saharan region including East African Submarine cable(EASSy) ,East African Marine System(TEAMS) and  the new undersea cables surrounding Africa will boost the broadband penetration rate from 3.2 percent in 2010 to 6.8 percent in 2015. New undersea cables will drive the growth of total broadband users in Africa from 40 million in 2010 to 92 million in 2015 at a CAGR of 18 percent, while revenue will increase at a CAGR of 16 percent in the same period to US$20 billion.

All these projects in Asia and Africa are expected to have a positive impact on all sectors - from education, to health, to entertainment, helping drive economic growth and creating job opportunities. An expanding network and falling prices are expected to fuel explosive growth in mobile broadband in Africa over the next few years, particularly Nigeria, which has overtaken South Africa to become the continent's largest mobile telecoms market.Enhanced capacity offered by these submarine cable systems will bring more competition among big operators such as South Africa's MTN and India's Bharti, which completed a $9 billion acquisition of the African operations of Kuwait's Zain.

Various cable systems have been formed all over the world over a period of time, considering the importance of submarine cables.The transatlantic cable systems(TAT series cables),South East Asia – Middle East – Western Europe cable systems(SEA –ME – WE1,2,3,4) and South Africa’s submarine cable network(SAT 1,2,3) are some of the submarine systems spread across the globe.

Submarine cable design & operations are constantly evolving. Future systems are expected to have even greater capacity and reliability. Cables, with sensors to detect chemical & physical changes, are planned for maritime & coastal defenses.

HITS

HITS( Headend in the Sky) is a satellite based delivery platform for delivering multi channel television signals to cable operators across the country.

 With HITS country wide implementation of CAS(Conditional Access System) becomes instantaneous and cost effective. This benefits both the broadcasters and customers by ensuring addressability.

At the same time, the HITS platform delivers a huge number of pay television channels. This provides the HITS end consumer the largest possible choice of pay channels. Since the HITS signals are delivered by a satellite, over a large "footprint" area, they offer even the most far flung rural HITS end customer an identical choice to that offered in large metro cities with elaborate Headends.

Operation-

Since a HITS platform carries a large number of channels, it is necessary to digitally compress these channels before transmission through satellite. Digital compression allows upto 10 channels (or even more) to be compressed on a single satellite transponder using advanced compression techniques such as statistical multiplexing , used along with MPEG-2 compression.

At the centralised HITS uplinking facility, signals of various pay channels are received and decoded using professional grade IRDs, each with the appropriate Conditional Access Module (CAM) necessary to receive each broadcast. These signals leave the IRDs as a digital compressed but unencrypted digital data stream. Analog transmissions if any that are received as separate video and audio signals (either from an FTA analog channel or a VCR playout) need to be compressed into an MPEG-2 digital stream. Each digitally compressed channel is now encrypted using a common encryption system (e.g. Conax for SitiSatellite) for the entire HITS platform. Approximately 10 of these encrypted, digital channel streams are multiplexed i.e. put together into

a single data stream and uplinked to a single satellite transponder.  The satellite transponder handles these signals as it would any other digital television broadcast. The C or KU band signal is simply bounced back to earth over the transponders footprint. The digital signals are received by a cable Headend or even a Last Mile Operator, as they would any other digital TV signal.

Transmission- Each LNB output, containing upto 10 digital pay channels is fed into a "Transmodulator". A Transmodulator receives QPSK signal from LNB (Low Noise Block Converter). These signals are in the range of 950 MHz to 2150 MHz. The transmodulators down converts this frequency to cable TV frequency( 48MHz to 860 MHz) while simultaneously changing the modulation from QPSK to QAM. The Transmodulator provides a digitally encrypted data stream for upto 10 pay channels. If a total of 50 pay channels are to be received, a set of 5 transmodulators would have to be installed at the Headend.

The output of the Transmodulators is a digital CATV RF signal. The output of all Transmodulators is then mixed with the analog free to air channel bouquet generated locally. Low cost CATV splitters or tapoffs can be used for mixing the digital and analog signals. The only precaution necessary is that the digital signals should be mixed at a level that is 10 dB below the analog signals.

Reception-Each HITS consumer will require a digital Set Top Box. These digital set top boxes will be provided by the HITS operator to the LMO. Each HITS box is embedded with its own, unique serial number and can be authorised to decrypt each specific pay channel that the consumer subscribes to. The digital Set Top Box is a DVB-C box i.e. a DVB box capable of receiving CATV transmissions over the frequency band of 48 MHz to 862 MHz. The STB is identical to what is provided by WWIL/ SitiCable for its ground distributed digital CAS.

Advantages of a HITS license-

HITS, as compared to other forms of digital broadcasting, is a more cost-effective

method of achieving digitization since it doesn’t require heavy investment from the cable

operator, who merely has to equip homes with set-top boxes and become a franchisee.

There are certain distinct advantages a HITS licensee has, namely:

1.       The licensed HITS operator is allowed to directly contract with various broadcasters

for buying their content.

2.       He can also put all the broadcasting content at one place (hub/teleport) and then uplink it, using his own encryption, to a satellite hired by him.

3.       The HITS operator can provide infrastructure facilities as well.

4.       The licensed operator can also provide simulcrypting/multicrypting of channels aggregated by different MSOs( Multi System Operators) with different encryption systems to one or more MSOs who wish to uplink these channels to a HITS satellite and then downlink them for transmission to the consumers.

      

HITS and DTH- A Comparision

HITS offers direct competition to the DTH operators. Unlike DTH, there will be sharing of revenue between the broadcasters, HITS operator and the various cable operators under the HITS system. The reception of signal is also expected to be better in HITS as compared to DTH transmission. Further, DTH operates only in Ku-Band, which is vulnerable to rain and causes deterioration of signal, whereas HITS is allowed to operate in both C-Band and Ku-Band. One can expect the DTH operators to change their business model to suit the new emerging broadcasting setup. The healthy competition amongst DTH and HITS operators will provide an impetus to digitization, narrow the digital gap between rural and urban areas and reduce prices of transmission of broadcasting signals and set-top boxes. In a bid to facilitate rapid digitalisation of Indian cable TV networks, the Union Cabinet has decided to grant HITS licenses without a recurring annual license fee. In contrast the DTH license requires each DTH platform to pay a recurring license fee of 10% of the annual revenue of the DTH platform. This includes 10% of not only the subscription fee but the selling price/hire charges of the STBs + Dish antenna also.