User talk:Hamid lal
The Next Generation Network-NGN In recent years, the telecom network has been developing rapidly, and the integrated communication ability has been enhanced greatly. However, the network faces more and more pressure from the gradual integration of telephone network, computer network and cable television network. Because the network load is increasing and service demands become diversified, the carriers have to provide more new services to attract users, which are hardly provided by the PSTN (Public Switched Telephone Network) or PLMN (Public Land Mobile Network). Meanwhile, the rapid-developing data networks are taking over some services from the PSTN and PLMN and play an important role in bearing voice service. Whereas, the Voice over IP (VoIP) based on the H.323 protocol can only meet the basic requirement for packet voice service, and cannot provide abundant service functions. PSTN was designed for Plain Old Telephone Service (POTS). This is the basic copper wire line service that allows point-to-point communications between telephones or low-speed modems. Switching in this system accommodates temporary communications such as phone calls. The calls are established through the switches and the whole circuit is reserved till the duration of the call. PSTN was designed for the provision of real time voice services as it provides a dedicated and uninterrupted communication channel. However, it is not suitable for the provision of data which is bursty in nature. Since the network provides a dedicated channel, the bandwidth is wasted for the duration of time in which the user is not sending any data. In such conditions, the Next Generation Network (NGN), which is based on the soft switch technology, comes into being. NGN is a milestone in the telecom field. It indicates the arrival of the new generation telecom network. In terms of the development, NGN is a step from the traditional circuit switched PSTN to the packet-based IP network. NGN bears all the services of the PSTN, offloads large amount of data transmission to the IP network to reduce the load over PSTN, and supports new services and enhances traditional services by taking full advantage of IP technology. In this meaning, NGN is the integration of TDM (Time Division Multiplex)-based voice network and IP/ATM (Asynchronous Transfer Mode)-based packet network. It enables the bearing of voice, video, data, etc. services over the new generation network. 3.2 What is NGN? NGN is an integrated and open network. It integrates all the existing network environments, ambient access devices and terminal products. NGN is a service driven network. By separating service from call control, and call control from bearer, it can realize a relatively independent service system and thus enables service independent from network. Such open service architecture can satisfy the users’ demands for services, strengthen the comprehensive competition ability of the network and realize the sustainable development.
Figure 3.1 NGN Network The next-generation network seamlessly blends the public switched telephone network (PSTN) and the public switched data network (PSDN), creating a single multiservice network. Rather than large, centralized, proprietary switch infrastructures, this next-generation architecture pushes central-office (CO) functionality to the edge of the network. The result is a distributed network infrastructure that leverages new, open technologies to reduce the cost of market entry dramatically, increase flexibility, and accommodate both circuit-switched voice and packet-switched data.
3.3 Features Of NGN: NGN has the following features:
Openness: NGN can be divided into several functional modules according to different networks interworked and different functions provided. These modules can not only be developed independently, but also act as a whole. Meanwhile, such openness also enables the carriers to choose the best products in the market as per their own requirements, without worrying about the interworking among different devices.
High efficiency: Since NGN can separate service from call control, it provides good conditions for the real independence of service from the network and effective minimization of the development period for a new service. Accompanying with the interworking of multiple networks, many new services are emerging. Diversified access: NGN integrates the advantages of PSTN, PLMN and IP network, which enables the communication among analog user, digital user, mobile user, ADSL (Asymmetric Digital Subscriber Line) user, ISDN (Integrated Services Digital Network) user, IP narrowband network user, IP broadband network user and even the user accessing via satellite. Multimedia: Real-time transmission of voice, video and other multimedia streams is another outstanding advantage of NGN.
Low cost: Compared with current PSTN, the adoption of relative cheaper networks such as IP network as the transmission bearer in NGN greatly reduces the communication cost. This advantage is more obvious in toll calls and international calls.
3.4 Why NGN? 1. Today’s Circuit switched Network do not support a variety of sophisticated services and applications, like multimedia. 2. Today’s Circuit switched Network is engineered to handle voice traffic with short holding times. One can imagine the impact of the increase in dial-up Internet traffic with its much longer holding times causing bottle-necks in Circuit-switched Networks. 3. Circuit switches are highly reliable elements within the PSTN infrastructure. However, they were never optimized for data. 4. Packet-based transport allows flexible bandwidth dimensioning, eliminating the need for fixed size trunk groups for voice, thus making it easier to manage network structures. 5. NGN will be service-driven, providing all means needed to offer new services and customize existing ones in order to generate future revenue.
Figure 3.2 Centralized Architecture of PSTN vs. Distributed Architecture of NGN In PSTN/ISDN most of the functionalities are located in a single exchange and may use proprietary protocols. However, in the NGN, functionalities are distributed amongst several elements.