 In this module, we'd look at the factors which we call as the drivers for NGN, which eventually determine how the NGN is going to look like. We'll start with having a look at how the classical systems offer their services, and then we'd also look at the changing landscape, which has resulted in the confluence and the convergence of these services. A classical communication system is the one that offers its inherent or native service. Since a variety of services have already been offered for a very long time through their dedicated network, we can say that these networks have existed quite much in parallel. Each type of these network is associated with some native service. With that native service, it is optimized to offer the service because the basic design of the network is such that a certain type of service can be best offered on that network. Let's take an example. If you look at the fixed telecom networks, the voice communication on public switch telephone networks is offered to the home subscribers on the twisted pair on the fixed telephone line. Similarly, in fixed and mobile networks, we have the voice communication that is providing mobility for the users which are using voice. So these two are these networks that we know as the PSTN and the PLMN, the public land mobile network. Then we also have the cable network. The cable network is known for offering the broadcast services in television and radio. The cable TV network initially was analog. Later it moved to digital, and it is providing digital TV channels and radio channels through a set top box. And then we have the internet which is offered to us through an internet service provider that provides us with basic internet speed for data. This could include offering the web services, email and FTP and other kinds of such services. Now these services are inherent to the internet. The cable services are for digital media transmission like televisions and radio. And then we have the PLMN and PSTN. With all such landscape, we can now imagine it to be changing. Why? Because every network provider which is providing its own intrinsic service is now also going to provide the internet service. For instance, on PSTN we have seen the DSL offering internet access to the home subscribers. Likewise in the mobile communication we see that in addition to the voice and SMS there are data packages available on 2.5G, 3G and even the 4G. So it means that we are now looking at a scenario where every service provider is now looking at services including internet in addition to its native services. At the same time, each service provider is also trying to incorporate features and services of the other network. For instance, the telecom networks which are primarily known for offering voice and data services are also now providing the broadcast services. That is the podcasting or the multicasting. Similarly, the ISPs are providing the telephony services. The cable net is now providing the internet service. In all what we see, a shift of the services provided by these networks to enter into the jurisdiction and domain of the other service providers. Let's look at the overall NGN driver summary. We are going to look at this diagram in much more detail over time. But here we are going to summarize it. I've taken this from the NGN architecture protocol and services. Now you see that from the service provider point of view we see that we had the telecom operator, the internet service provider and the TVN radio broadcaster. They are now converging into one. This means telecom provider is also trying to be an ISP as well as broadcast the television content. Likewise, for internet service provider they are offering the IPTV and the voice over the data network that is through the internet. So we see that the market is going to converge and eventually we are going to see next generation network that is seeing the merger of these service providers. From the technological viewpoint we see that all these service providing physical networks such as the public switch telephone network, the land mobile network, the internet and the native broadcasting networks are now all emerging to a convergence. This convergence is primarily based on IP. So next generation network is actually coming into play after the convergence of both the market and the technology. We are going to spend a good number of lectures on this.