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Export of IT Services
Data Communication in Nepal
The role of IT: Efficiency or Burden?
Sharing Multimedia Endeavor
Intelligent System
Memory Hierarchy

Emerging Technologies



Emerging Data Communication Technologies


Shailesh Khanal

Published in CORE, Sep/Oct, 1997


Tradition says computers are productivity tools but in today' s world of Internet and Intranets, they are gradually taking up additional role of communication tools. This transformation or encroachment into communication area is mainly due to advancement in processing power, better storage, reliable and faster communication technologies. In the early days, computer communications were limited to simple text transfers, now they are growing continually richer in feature and function; as a result they are becoming more and more demanding. Today computer communication includes multimedia, PC video conferencing, 3D graphics which require millions of bytes to be transferred between computers. It can now be mathematically proved that a picture (in Megabytes) is worth a thousand words(in Kilobytes).


Massive growth of Internet in the last couple of years has changed personal and business computing paradigms. Many new applications such as database access via Internet, teleconferencing, home office, distance learning, interactive TV programming, video on demand, on line shopping are all closer reality now. But trying to run these complex applications over a 28.8 Kbps (Kilo ~ Bits Per Second) dial-up connection or even a 10Mbps LAN is going to be frustratingly slow.


Although no simple solution exists, there are some new technologies on the horizon. Some of them are to speed up remote and Internet access and the other accelerate LAN and WAN connectivity. These technologies are likely to emerge between now and the year 2000.


Story So far

Unless you are one of those lucky ones using a corporate or university LAN, you must be using an analog modem to access Internet. Though analog modems have their limitations, they are still the cheapest way to hook into the Internet. The new modems which utilize V.34 protocol standards can achieve transfer rates up to 33.6 Kbps. But it still does not help you much if you are downloading a good Cindy Crawford picture.


In business sector ISDN (Integrated Services Digital Network) is gradually getting its foothold, at least in developed countries. As its name implies, ISDN can integrate voice and data in the same communication channel and it is well suited for multimedia applications. ISDN provides three separate channels on a single copper telephone line, as opposed to one provided by analog modems. These channels include two 64 Kbps B-Channels for voice and data transmission and a 16 Kbps control channel. Protocols allow the two B-channels to bond to become a single channel with transfer rate of 128 Kbps, which is nearly a few times that of the fastest among modems.


Present day communication applications have become so demanding that even ISI)N does not look so impressive as it was few years ago. People have already started calling it "It Still Does Nothing". Also not all the countries offer ISDN. Even if they are offered, the central telephone company switches become the bottleneck as they were designed for basic voice communication, hot for data communication.


56 Kbps Analog Modems

56 Kbps analog modem is on the lower end of the emerging Internet technologies. This technology is based on chipsets (K56Flex Technology) developed by Rockwell International Corp. US Robotics already has released 56 Kbps modem under a trademark of x2: Other modem vendors are also expected to follow suit.


Most developers and analysts still believe that 33.6 Kbps is the maximum achievable rate for analog transmission over normal telephone lines. This is due to the inherent noise problem in telephone lines. The 56 Kbps modems work around this limitation by capitalizing on digital conversion process that most analog calls undergo at the phone company. In a typical client computer to host computer communication, digital data from the client computer is converted to analog signal, transmitted via public phone network and finally converted back to digital signal at the host computer and vice versa. The signal conversion is taken care of by analog modems. The K56Flex technology takes advantage of the fact that many of the Internet Service Providers use digital lines to connect to the telephone company. So a higher speed can be achieved by eliminating the conversion process at the server side. This imparts asynchronous characteristics to the 56 Kbps moderns making 56 Kbps transfer rate available for one way (downstream, that is carrier to desktop) only, the upstream transfer rate can be as high as 33.6 Kbps (US Robotics modem).  The 56 Kbps modem looks very attractive to a typical Internet user whose download traffic is far more than upload traffic. Users can enjoy speeds close to one ISDN B -Channel. This asynchronous transmission is however not well suited for applications like video conferencing and large data uploads. Another drawback is that it can only connect to digital modems, this eliminates standard modem-to-modem transfer between home and office. 

Cable Moderns

You have heard enough about cable TVs and number of channels they provide. Now let' s talk about cat>le modems. A cable modem is a device that sits between a PC (or other terminal) and a cable TV network, and allows the PC to send and receive data. Isn't that great? Imagine yourself accessing Internet while your folks are enjoying Zee TV. Cable Modems do exactly the same job as analog modems but at a much faster rate. This is because cable TV company uses coaxial cable rather than twisted pair used by phone company, and can carry more information, more quickly. Cable modems and hybrid fiber optic/coaxial lines can transfer data at speeds of upto 30 Mbps downstream and upto 10 Mbps upstream, far surpassing the capabilities of ISDN, that also at a fraction of the cost of ISDN. Another advantage is that they are always online, no hassle of dialing the service provider.


Cable modem solutions are aimed at both residential and business use with focus on Internet access. But it can also be used to provide more sophisticated real-time services, particularly for business community.


Like any other technology, the cable modem also has its own drawbacks. The cable modem system effectively turns the cable TV system into a very large LAN, which means users have to share the available bandwidth with airy other active users on the same node, resulting in a reduction in data throughput as the number of users increases. Also the cable modem network is believed to be insecure, because anyone with access to the cable network can tap the data flow.


Despite the obvious potential in cable modems, the cable companies have a long way to go. The most important factor is the huge investment required to upgrade the infrastructure for data communications. Cable modems can succeed in the market place only if the issues of standardization, security and bandwidth guarantees are resolved. 


Digital Subscriber Line

Digital Subscriber Line (DSL) technology is one of the latest additions in communication technologies making a big impact in the industry. It is expected to have a dramatic societal impact on both our personal and professional lives. Stated simply, DSL provides high-speed multimedia services, such as video-on-demand, super-fast Internet access, distance learning and video phoning to anyone with a standard, copper telephone line.


Compared to other currently available technologies, DSL modems offer the highest transmission reliability, the fastest speeds and interactive capabilities, for the least investment. DSL modems available today can download die entire Encyclopedia Britannica in 31 minutes compared to 27 hours with a common 28,800 Bps modem.


Among various DSL technologies, ADSL has become a favorite buzz word among the communication technologist. ADSL stands for Asymmetric Digital Subscriber line. With ADSL, interactive Multimedia services can be provided to almost anyone with a telephone line in their home or business. From a subscriber's perspective, ADSL is completely transparent. It is a modem like technology, in that it is placed at either end of a telephone line. ADSL interfaces between digital sources containing information and provides a channel of communication very much like a typical analog modem. The primary difference however, is speed. ADSL is capable of throughputs from 1.544 Mbps to 8 Mbps over standard telecommunication loops.


It does not, however look very promising if compared with cable modems in terms of the raw data transmission rate only. The major advantage of ADSL over cable modem is that it uses standard telephone lines so new investment in infrastructure is not required. AI)SL can also use a leased line, rather than a switched one, which allows subscribers to have point-to-point connection and hence better data security ADSL can also be an attractive alternative to ISDN because the lines are specifically configured for each connection and the connection is constant, rather than dependent on the Public Switched Telephone network (PSTN) which is need by traditional and ISDN and was designed for regular voice traffic .


Due to its feature and price, ADSL is one of the most waited technology in networking area.


Wireless Cable

Wireless cable is a new technique for two-way transmission of high speed digital data using microwave links to homes and office. Wireless cable involves Multichannel Multipoint Distribution Services (MMDS) which is expected to provide 10Mbps downstream transmission rate for Internet access and telephone services in a way not possible with present phone line moderns and at the same time can be used for transmission of digital TV movies.


Since the system is wireless, this system can be installed at only the cost of the equipment required for those actually subscribing, rather than the cost of equipment I for thousands of homes that must be passed by cable but are not yet subscribing.


Wireless cable technology has great potential for mobile communications. But, because of technological complexity and high cost, it is likely to target the corporate segments only. It is relatively new and has not caused much stir in the industry yet.

Gigabit Ethernet

Ethernet is the most popular LAN technology with very large installed base. Most of the current Ethernet LAN use 10 Mbps transfer rate, which is clogged by new graphic and multimedia applications. Next generation of Ethernet, that is 100 Mbps Ethernet was introduced in January 1995, which is steadily taking the market by storm. The migration is made simple by LAFJ interface cards with dual speed (10/100 Mbps) capability. If 100 Mbps network cards are used at desktop then users will naturally seek more power at the backbone. This is where the newborn Gigabit Ethernet takes its place.


Though Gigabit Ethernet is relatively new technology industry is buzzing with it. Many vendors already have products for it based on their own standard, this might lead to incompatibility problem if they are not based on standard specifications. Currently the IEEE 802.3 Ethernet task force is working to develop standards that will allow 1000 Mbps connections between 100 Base Trousers and switches. Once the standards are set and incompatibility issues are resolved, Gigabit Ethernet should go long way.


Asynchronous Transfer

ATM has been one of the most talked about technology in the communication industry for the last few years, but it has not
gathered much momentum in terms of actual deployment. This is mainly due to its high cost and- constantly changing standards.


ATM is a cell-switching technology which combines the high-speed efficiency of packet switching used in data networks and the bandwidth reliability of circuit switching, which is commonly used in voice
networks. ATM is extremely fast and scaleable, operating upto 2 Gbps. Other feature advantages include high interpretability between desktop, LAN, and WAN, as well as the ability to multiplex several data types simultaneously across a single network.


Though ATM can bring extreme capabilities to the LAN, at this point the technology seems most suited for WANsmainly due to its high cost. Migrating from existing 10 Mbps network to ATM will be many more times costlier than migrating to 100 Mbps network. However, at the WAN level it is competitive with other existing technology such as Time Division Multiplexing. Because of its ability to convert other data types into fixed 53-byte cells it uses, ATM also can incorporate existing services such as Frame Relay, X.25, and Internet traffic.


Currently ATM is taken as panacea by the industry and developers are trying to use it with' everything that exists today: IPXI IF, Apple Talk, and any other protocol. But in future ATM will be mostly used in voice and video-conferencing areas.  


What to Look for Ahead?

It must be accented that one data transmission technology will never solve the bandwidth problem. If network traffic is not the bottleneck then servers, switches or even software can become bottleneck. A high speed data communication technology will only be useful if other network components can pump the data at the same or higher speed. Obviously if data communication becomes faster, it will give a drive to other network component vendors to match their products with the transfer rate available.