Advantages of fibre-optic Communications:
1) Extremely high bandwidth – No other cable-based data transmission medium offers the bandwidth that fibre does.
2) Easy to accommodate increasing bandwidth – Using many of the recent generations of fibre optic cabling, new equipment can be added to the inert fibre cable that can provide vastly expanded capacity over the originally laid fibre. DWDM, or Dense Wavelength Division Multiplexing, lends fibre optic cabling the ability to turn various wavelengths of light travelling down the fibre on and off at will. These two characteristics of fibre cable enable dynamic network bandwidth provisioning to provide for data traffic spikes and lulls.
3) Resistance to electromagnetic interference – Fibre has a very low rate of bit error (10[SUP]-13[/SUP]), as a result of fibre being so resistant to electromagnetic interference. Fibre-optic transmissions are virtually noise free.
4) Early detection of cable damage and secure transmissions – Fibre provides an extremely secure transmission medium, as there is no way to detect the data being transmitted by “listening in” to the electromagnetic energy “leaking” through the cable, as is possible with traditional, electron-based transmissions. By constantly monitoring an optical network and by carefully measuring the time it takes light to reflect down the fibre, splices in the cable can be easily detected.
Disadvantages of Fibre Optic Communications:
1) Installation costs, while dropping, are still high – Despite the fact that fibre installation costs are dropping by as much as 60% a year, installing fibre optic cabling is still relatively costly. As installation costs decrease, fibre is expanding beyond its original realm and major application in the carrier backbone and is moving into the local loop, and through technologies such as FTTx (Fibre to the Home, Premises, etc,) and PONs (Passive Optical networks), enabling subscriber and end user broadband access.
2) Special test equipment is often required – The test equipment typically and traditionally used for conventional electron-based networking is of no use in a fibre optic network. Equipment such as an OTDR (Optical Time Domain Reflectometer)
is required, and expensive, specialized optical test equipment such as optical probes are needed at most fibre endpoints and connection nexuses in order to properly provide testing of optical fibre.
3) Susceptibility to physical damage – Fibre is a small and compact cable, and it is highly susceptible to becoming cut or damaged during installation or construction activities. Because rail and power network services often provide rights-of-way for fibre optic installation, train derailments and extreme weather damage to overhead power lines pose significant cable damage threats, and these events can disrupt the service to large groups of people, as fibre optic cables can provide tremendous data transmission capabilities. Because of this, when fibre optic cabling is chosen as the transmission medium, it is necessary to address restoration, parallel backup and survivability.
4) Wildlife damage to fibre-optic cables – Many birds, for example, find the Kevlar reinforcing material of fibre cable jackets particularly appealing as nesting material, so they peck at the fibre cable jackets to utilize bits of that material. Beavers and other rodents use exposed fibre cable to sharpen their teeth and insects such as ants desire the plastic shielding in their diet, so they can often be found nibbling at the fibre optic cabling. Sharks have also been known to damage fibre optic cabling by chomping on it when laid underwater, especially at the repeating points. There is a plant called the Christmas tree plant that treats fibre optic cable as a tree root and wraps itself around the cable so tightly that the light impulses travelling down the fibre are choked off.
Satellite communication provides a number of advantages :
1)Flexibility: Satellite systems are able to provide communications in a variety of ways without the need to install new fixed assets.
2) Mobility: Satellite communications are able to reach all areas of the globe dependent upon the type of satellite system in use, and the ground stations do not need to be in any one given location. For this reason, many ships use satellite communications.
3) Speedy deployment: Deployment of a satellite communications system can be very speedy. No ground infrastructure may be required as terrestrial lines, or wireless base stations are not needed. Therefore many remote areas, satellite communications systems provide an ideal solution.
4) Provides coverage over the globe: Dependent upon the type of satellite communications system, and the orbits used, it is possible to provide complete global coverage. As a result, satellite communications systems are sued for providing communications capabilities in many remote areas where other technologies would not be viable.
Satellite communication has some disadvantages:
1) Cost: Satellites are not cheap to build, place in orbit and then maintain. This means that the operational costs are high, and therefore the cost of renting or buying space on the satellite will also not be cheap.
2) Propagation delay: As distances are very much greater than those involved with terrestrial systems, propagation delay can be an issue, especially for satellites using geostationary orbits. Here the round trip from the ground to the satellite and back can be of the order of a quarter of a second.
3) Specialised satellite terminals required: Even though the operator will operate the entire required infrastructure, the user will still need a specialised terminal that will communicate with the satellite. This is likely to be reasonably costly, and it will only be able to be used with one provider.
