An internet connection is one of the most essential services that any person pays for today. It is as important as power and other utilities that are essential for any home to be considered livable. It’s good to know about the underlying technology that’s delivering the World Wide Web content to your devices at home, as well as carrying out information to be delivered to your desired application and recipient. There are two major technologies used to bring the internet to residential areas: coaxial cable and optic fiber. Other methods of the internet are satellite and publicly available WiFi. In this article, we’ll focus on home internet services, as business internet connections are much faster and have much more capacity to transmit and receive data using more advanced and expensive technology. There are underwater cables fixed to the ocean floor connecting the different continents. They’re fiber optic material and called the “backbone”. This backbone is passed through a series of locations until eventually reaching residential subscribers via coaxial cable. Where fiber is available for homes, many people may prefer that due to its superior performance.
Cable TV infrastructure has been in place across towns and cities in America for a long time now. Cable internet takes advantage of this existing infrastructure to piggyback internet communication at very good quality. Named Data Over Cable Service Interface Specification (DOCSIS) is a standardized protocol for internet use on the existing cable TV (CATV) system. The data transfer of the internet using this method is high-bandwidth, which means you get better download speeds than possible with previous technologies. The internet download is assigned to a specific channel and then upload to another channel. In this system, the cable TV distributor location (master headend) transmits TV channels to neighborhoods via “trunk” optical fiber lines. The master headend has all sorts of advanced satellites to catch long-distance video signals as well as routers for internet connections. Then at the neighborhood location (regional headend) a box (a node) translates the signal from the light beam to radiofrequency (RF). From here, the coaxial cable comes into play, bringing the data to your home. Public, educational, and government access channels are added at this stage. Local advertising may also be placed at this point in the network. At this stage, a digital-to-analog conversion takes place, called modulation. A neighborhood of as many as a couple of thousand homes can be served by a single optical node. Between the node and your home, RF signal amplifiers are necessary to ensure the signal is not degraded before reaching your residence. The coaxial part of the network is arranged in a tree and branch configuration. It is important to note that all at this stage the residences share the node. A technique called Frequency Division Multiplexing is used to carry digital HDTV, VOD, telephony, and high-speed data on the same physical line. Even cooler, this physical line is bi-directional, meaning you can send and receive the various types of signals simultaneously. Signals are sent to the residences in electromagnetic form. At your home, the router does the job of demodulation of the signal, converting it back into the original signal bearing the data that you downloaded. Major internet service providers such as Cox Communications currently require at least DOCSIS 3.0 routers. The maximum theoretical download speed on this router is 1.2 Gbit/s.
The optical fiber cable is an awesome technology that’s still not fully accessible to all residential neighborhoods even in advanced countries like the United States. The fiber or strand of narrow wire carries signals in the form of light. We all know that the speed of light is pretty high. In fact, we can’t really perceive anything going faster than this rate of speed. In a vacuum, the speed of light is 186,000 miles per second (300,000 kilometers per second). The optical fiber consists of a core that is enclosed within a cladding layer. Enclosing these layers is a protective coating to shelter the system from the elements as well as any damage due to the general maintenance of buildings and streets.
The refractive index of the core, n1, is always greater than the index of the cladding, n2. Light is guided through the core, and the fiber acts as an optical waveguide. The phenomenon of total internal reflection is utilized to propagate the signal down the wires. A light ray enters the fiber optic cable, preferably within the “acceptance angle”. If the light ray hits the core-cladding boundary at an angle greater than the critical angle with respect to the vertical plane, total internal reflection occurs. This means that the ray has been reflected back into the core and will now move forward, hitting the core-cladding boundary at a further point. The angle of incidence is always equal to the angle of reflection. This way, the signals are sent along the optical fiber cable, and into your home. That is not to say that fiber optic internet technology is flawless. If the angle of incidence of a light ray on the core-cladding boundary is less than the critical angle, reflection and refraction both take place. The light beam “attenuates” and dies off over distances. This is measured by the Bit Error Rate (BER). The major factors that affect the performance of the fiber optic cable are the size of the fiber, the composition of the fiber, and the mode of propagation. The propagation modes are multimode or single-mode. There are internet service providers offering fiber internet service in the US.
Although fiber optic internet service in the “last mile” does make a big difference to the speed and quality of the homeowner and their family’s experience, the cable internet is also pretty decent for our needs. If you really want a top of the line internet service experience, you can go for fiber. Otherwise, HD streaming, gaming at low ping and lag, browsing on tablets and computers, and using social media on your cellphone at home is served well by cable internet.
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