Bandwidth can be the difference between the lowest and highest frequencies. The available frequency is divided into several channels using Frequency Division Multiplexing Technique (FDM). Higher bandwidth helps to get many numbers of channels and increases the data carrying capacity. Different types of data including text, voice, and video will be sent through each channel. One common application is Cable television.  The Cable TV subscriber will be connected to CABLETV office through a coaxial cable.  Some times open-air media is used, so each program is televised in a different channel.  That means there is only one wire with a broad Bandwidth, so CABLETV operator can transmit many programs along with Cable Net (Internet) services through same Coaxial cable, the decoder at user's end will separate different frequencies (you can change between the frequencies by pressing the channel button on your remote). Off course, cable modem is required at user’s end, if the user wishes to utilize the cable net services.

Coming to the cost of Bandwidth, in case of closed media, Bandwidth is very cheap, neither operator nor user required to pay higher license fees to government, because the signals are not moving out of the media, so, very limited number of chances for unacceptable interference, but in case of open-air media, Government usually issues licenses basing on the availability of Bandwidth and operators requirement.  If frequency f1 is allocated to company A, then the same frequency band can’t be allocated to others, otherwise two companies would use the same frequency signal, which would cause unacceptable interference.  Because of this limitation, many number of people who wish to use this open-air media for communication compete with each other, so, obviously Government will have much more bargaining power and fixes the price.  Though this is the costly affair, still some of the companies choose to use open-air media for communication and to provide Free-to-Air and Pay TV services.  For example Fiji Television in Fiji provide services through open-air media, because this is the only reliable method to provide services to more than 300 islands.  Besides, transmission through closed media will be very expensive, because cables are to be put under the sea to smaller islands from the main Island.

Now a days, to minimize the problems with the limitations, researchers have come up with different modulation techniques to increase the bit rate using the same band with.  In case of Mobile communications, cellular technology and frequency reuse are the most important revolutionary steps to provide mobile services to many number of users.

Written by: Srimannarayana Grandhi
Company Name: Central Queensland University Fiji International Campus
Phone: 3313755 Extn.255
Email:grandhis@cqufic.ac.fj
Website name & URL address: http://www.suva.cqu.edu.au