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The evolution of Broadband Internet serviceBroadband Internet Service The evolution of Broadband Internet service The confluence of two forces-the globalization of business and the networking of information technology has created the internet economy. Electronic commerce and technology industries are changing the economy of the world at breathtaking speeds. The new economy is defining how people do business, communicate, shop, have fun, learn and live on a global basis- connecting everyone to everyone. As the internet market continues to explode, demand for greater bandwidth and faster connection speeds has led to several technological approaches to provide broadband internet service access to all consumers. Ubiquitous broadband access to the internet is an essential ingredient needed to gain the most out of what the internet has to offer. Any operator that fails to announce and implement a broadband strategy, including providers serving rural communities, will suffer consumer defections and a decline in retention rates for both business and residential customer. Broadband internet service is not only about providing the pipes to carry the traffic on the internet but also about how the traffic will be carried. Demand forBroadband Internet serviceAs the internet market continues to explode, demand for greater bandwidth and faster connection speeds have led to the development of several technological approaches to provide broadband internet service to all consumers. The demand is driven mostly by growth in data volumes as the internet and related networks become more central to business operations. Today's telecom industry is undergoing a bandwidth shortage driven mostly by continuing explosion of the internet and data markets. Demands come from three primary sources: small and mid-size businesses and small offices/home offices( SOHO ), consumers, and multiple-tenant units(MTU) or in-building fibre builders and universities. The rapid growth of distributed business applications, the proliferation of private networks, e-commerce, and bandwidth-intensive applications(such as multimedia, video conferencing) all help fuel the demand for bandwidth. The demand for bandwidth has led to several technological approaches developed to provide broadband access to business and residential. Here are the major techniques that are using to connect the broadband internet service now days. ISDNCommunications networks have evolved at different times from a number of different requirements. The oldest are those, like the telephone and telex systems, which arose to support voice and text transfer; then came those inspired by the requirement for computers to exchange asynchronous data; and, most recently those intended to support the most demanding high-bandwidth asynchronous data generated by multimedia applications. Although these needs have arisen at different times, and to some extent, initially generated quite different solutions, it has long been a goal of network providers to unify them and establish networks capable of providing users with a communications service to handle all forms of data. The first major international effort to achieve this integration of services was published in 1984 under the auspices of the CITT. This somewhat predated the explosion of interest in high-bandwidth multimedia that has occurred in the 19990s, and the emphasis was therefore more on unification of voice and data. However, it was a concrete effort to establish standards that could realise the aspiration of a unified service. The initiative recognized that all WANs, including the telephone network, would soon be digital, as was therefore called integrated services digital network or ISDN. There are a couple of points worth making at the outset. Firstly, ISDN was envisaged as an attempt to create a wide area network and network service, based largely on the IDN telephone infrastructure. It did not consider the position of LANs, which were seen at the time as being primarily for the transfer of asynchronous data between local computers. This is not to say that ISDN is incompatible with LANs, simply that ISDN service was seen as being offered to subscribers by a public network just like PSTN and the packet-switched data network(PSPDN) which were springing up at the time. ISDN was to be a unification of the circuit-switched IDN and the PSPDNs, which would offer addition services besides. Secondly, when ISDN was designed it was not appreciated just how much bandwidth the integrated services of the future would require. Several years later, when this became apparent, CCITT realised that much higher bandwidth technology would be required, and by 1988, had first published the first recommendations concerning standards for a much higher bandwidth ISDN network. This required postulation of technology that did not at that time exist and was an altogether much more ambitious undertaking than the original ISDN proposals. To distinguish the two, the later version is known as broadband ISDN or B-ISDN, and the original is now sometime referred to as ?narrowband' ISDN.
DSLThe need to connect residences and businesses to the internet, or to remotely attach them to the company LAN, caused increased demand for digital connections. While ISDN is one alternative, another technology is Digital Subscriber Line or DSL
Broadband Internet service. Originally developed by Bell core, DSL was intended to deliver high-speed digital connections over copper cable from the central office to the residential or business user without the expensive repeaters found in T-1 lines. DSL was offered in many variations, hence the term xDSL, where the x defined the type of service being offered. All operate over twisted pair wire, and not all variations and speeds are offered in all areas. Asymmetric Digital Subscriber Line or ADSL Broadband Internet service, offers a transmission path that is of a higher speed in one direction than in the other. The central office sends data to the user of the ADSL line with a higher speed than the user sends data to the network. Applications like residential internet access can certainly benefit from this arrangement, since in most cases, the majority of data flows from the internet to the user. ADSL is available at speeds ranging from 1.5 to 9 Mbps in the high-speed direction and 16 to 640Kbps in the low-speed direction, over a single twisted pair. One popular combination is 6.1Mbps/640Kbps for specific distances and over certain-quality wire. Rate-Adaptive Digital Subscriber Line or RADSL, simply scales back the speed of ADSL based on the quality of the wire and distance between the user and the central office. A newer version of ADSL, known as Universal Asymmetric Digital Subscriber Line or UADSL, and also as ADSAL Lite, and G. Lite, is an attempt to standardize ADSL deployment across all carriers, since early implementations had so many speed and transmission differences. It operates using a 1.544Mbps/384Kbps combination. High-bit-rate Digital Subscriber Line or HDSL, offers 1.544 Mbps or 2.048 Mbps transmission in both directions, but requires two twisted pairs; HDSL2 is a recent version HDSL that operates at the same speeds and distances as HDSL does, but over a single twisted par. Single-line Digital Subscriber Line or SDSL, offers speeds ranging from 384Kbps all the way to HDSL speeds, but over shorter distances, using only a single twisted pair. One application of HDSL, HDSL2 and SDSL is to connect businesses to the internet. Very-high-bit-rate Digital Subscriber Line or VDSL, offers even higher speeds, but is asymmetric, with the high speeds ranging from 12.96 to 51.84 Mbps and the low speed from 1.6 to 2.3 Mbps. Its distance is very limited and one popular application of it is a local connection to a higher speed fibre optic network. There are numerous other xDSL versions, all with their own speeds and distance limitations and the technology is continually improving. No signal DSL choice is clearly superior to the others. Rather, it is a question of matching the transmission speed with the user's application. Also, all of these DSL versions simply provide a digital pipe from the central office to the user. Once the data reaches the central office, the carrier must then pass it to the data network(e.g. the internet) using the B-channels in the ISDN network or some other means. Cable Modem Broadband Internet serviceThe data rate limitation of traditional modems is mostly due to the narrow bandwidth of the local loop telephone line(up to 4 KHz). If higher bandwidths are available, one can design a modem that can handle much higher data rates. Fortunately, cable TV provides residential premises with a coaxial cable that has a bandwidth up to 750MHz and sometimes even more. This bandwidth is normally divided into 6 MHz bands using frequency division multiplexing. Each band provides a TV channel. Two bands can be set aside to allow a user to download and upload information from the internet. For the downloading it usually requires a 6 MHz bandwidth in a range above 40MHz. The demodulation technique used is 64-QAM(6bit a time). This means that a user can download information at a rate of 6Mhzx6=36Mbps. However, PCs are not yet capable of receiving data at this rate,. Presently, the rate is something between 3 and 10Mbps. On the other side, uploading requires a 6 MHz bandwidth in a range below 40 MHz. At this low frequency, home appliances can create a noisy environment that affects modulation. The modulation technique that is normally used is QPSK(4bits at a time). This means that a user can upload information at a rate of 6MHzx2=12Mbps. Presently, the uploading rate is between 500Kbps and 2 Mbps.
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