Wireless communication has greatly changed the way the world used to communicate. It has eliminated the need of wired communication to a large extent thus making the whole process quite hassle free. In this article we discuss in brief about the various wireless technologies that are used as the communication media.
1. Terrestrial Microwave
– This wireless communication technology employs the earth based transmitters as well as receivers that bear a resemblance to the satellite dishes.
– The range of the terrestrial microwave is quite low and lies in the low giga – hertz range.
– This is the reason why the communication is limited to the line of sight.
– The distance between any two relay stations is around 30 mi or 48 km.
– Bluetooth, IEEE 802.11 are other such wireless LAN protocols that operate on ISM band of 2.4 GHz.
– WIMAX service is another option open to business customers for communication and can be operated on 3.65 GHz.
2. Communications Satellite
– The medium through which the satellites communicate is the microwave radio waves which have a greater transmission range than the terrestrial microwaves.
– Another characteristic feature of these microwaves is that they do not get deflected by the atmosphere of the earth. – The satellites are positioned at various positions in space.
– Typically, the satellites are positioned in an orbit called the geosynchronous orbit.
– This orbit lies at around 22000 mi (i.e., 35,400 km) above the equator.
– The satellites are designed as such that they can receive and relay data, TV signals and voice.
3. Cellular and PCS systems
– The cellular devices that we use today work on the principles of the radio communication technologies.
– The region covered by these systems is divided in to a number of geographic areas by the systems themselves.
– A radio relay antenna or a low – power transmitter is built in every geographic area so that the calls can be relayed from one area to another.
4. Radio and Spectrum technologies
– High frequency radio technology is used for operating a wireless local area network (LAN).
– However, some features of this technology can be traced back to the low – frequency radio technology and digital cellular as well.
– But to make the communication between a numbers of devices in a LAN, the wireless LAN employs the spread spectrum technology.
5. Infrared communication
– This technology is used for small scale communication.
– Signals can be transmitted only for distances as small as 10 m only.
– However, there are many cases that involve line of sight propagation.
– But this leads to a disadvantage – difficulty in determining the physical positions of the communicating devices.
– Infrared light has got long wavelengths when compared to the visible light.
– Most of the thermal radiation given out by the objects is occupied by this wave of the electromagnetic spectrum.
– This technology is also used by establishing communication among the computer hardware devices over a small range of distance.
– But for this to be done you should make sure that the devices confirm to the standards of IrDA (infrared data association).
– Another characteristic feature of this technology is that, there is no interference from the devices on the other side of the wall since the waves cannot penetrate the walls.
– This wireless technology proves to be highly useful in indoor situations with very high population density.
– Remote control appliances make use of this technology only and are controlled by remote control protocols.
6. GAN or the global area network
– This network has been particularly helpful in providing support to mobile across a vast collection of LANS, areas covered by satellites and so on.
– Handling the user communications from one LAN to the next proves to be the toughest challenge in the field of mobile communications.