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TECH TALK: Next-Generation Networks: Convergence Areas

August 1st, 2005 · No Comments

This weeks Tech Talk is written by Ninad Mehta. Ninad works at Lucent in New Jersey, USA. Ninad and I used to work together at NYNEX Science & Technology during 1989-1991 and we were also room-mates. Ninad has extensive experience in telecom. So I invited him to elaborate on next-generation networks.

Last week, in the tech-talk series on Next Generation Networks, we covered the following topics: Convergence and what it means, the Rationale behind convergence, what is IP Multimedia Subsystem (IMS) and its role in convergence and what would a Converged NGN in the future look like.

Lets do a deeper dive on some of these topics. While we understand that Convergence can have different meaning to different people, in broad terms, convergence is happening in four major areas: Applications, Endpoints, Access Networks and Core Networks. Lets take these one at a time.

Applications convergence is easy to understand by an example such as Unified Mailbox where voice, e-mail, fax etc. all arrive in the same e-mail application inbox. Additionally, you would also want to share data that is common, across all these applications. Application convergence has been happening for many years now.

We have also seen Endpoints converge (mostly into cellphones) so that we can use one device to make phone calls, browse the Internet, send e-mails/SMSs and also perform functions traditionally available in PDAs (such as calendars, contact lists, reminders, to do lists, calculators, etc.). With larger and higher resolution displays becoming common on todays cellphones, portable gaming devices have also started converging into cellphones. We also hear about wireless and wireline convergence in the form of Wifi enabled cell phones that will use the home broadband connection for carrying voice when a wifi network is available. This will reduce the opex costs for the wireless service provider and benefit the consumer in the way of lower per minute charges.

Lets talk about the core network convergence from separate TDM, ATM and IP to a multiservice IP/MPLS network. The main drivers for the convergence in the core are: reduced operational costs, faster and cheaper delivery of new services, customer configurable virtual private networks, etc. British Telecom has launched a major initiative called 21CN for an All-IP network.

What is Access convergence? Here I am talking about the evolution in the access network technology that connects end user devices to the service providers. You might think that with all sorts of broadband options available in the last mile, the access network is NOT converging. This is partly true while the last mile part of the access network seems to diverge into different technology options, the migration of end-user services is clearly from carrying bearer traffic over {analog, cable, wireless, TDM, ATM, Frame Relay, SONET/SDH} to carrying bearer over IP. In other words, instead of having our analog phone carrying analog voice signals to the PSTN network, we are migrating to VoIP. Instead of carrying voice over a GSM/CDMA/TDMA interface, we will be migrating to VoIP over these air interfaces. Instead of analog video carried over cable/FTTx, we are migrating to various forms of Video over IP. This brings up a fundamental question- why bother to supplant all these well-entrenched technologies with IP? Arent the traditional technologies we have been using for decades more reliable and cheaper? Arent IP based devices more expensive and error prone as they have lot more software? The answer to these questions is beyond our discussion in this tech-talk series but the key takeaway is that with proper encapsulation, many services can be carried over IP. Also, beyond the technologies visible to end users, there is convergence happening in the access network to core network interfaces. So, traditional Remote Terminals with TDM and ATM interfaces are migrating to Ethernet interfaces. Moreover, the traditional wireline access network elements and the cellular network elements are also coming together with IP interfaces into the core network.

Tomorrow, we will talk about the next generation services enabled by the NGN and why service providers plan to spend billions in the coming years to build these NGNs.

Tomorrow: Services and Business Models


TECH TALK Next-Generation Networks+T

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