Telecommunication
While discussing the vast topic of telecommunications, it is important to mention the types of telecommunication network connections that are most commonly used in order to achieve effective communication. They are of three major types. Namely:
Switched Network Connection: This type of network is typically based on switched connections which are also referred to as dialup connections. The network utilizes switches arranged somewhat in a series, in order to establish a connection between the various elements.
Leased-line Network Connection: The second most common type of network connection used in telecommunication is the leased line network commonly referred to as a private line. As the name indicates, this type of network allocates the same particular locations and devices to be connected always. Moreover, the same path is used for data is transmission between the fixed locations and/or devices.
Dedicated Network Connection: The dynamics of this dedicated network connections are very similar to that of leased line. True to its name, a dedicated connection implies that always the same path will be used for data transmission between fixed always connected locations. The difference between the two is however that the end user may own the transmission facility instead of leasing it. This means that dedicated network connection may not be divided among a multitude of locations/users but be exclusive to that user only.
The field of telecommunication utilizes the electromagnetic spectrum, particularly the middle of this spectrum i.e. the radio waves, the micro waves, infrared, and visible light, in order to achieve various forms of communications.
In order to generate information carrying electromagnetic waves these mentioned portions of the spectrum are extensively used.
Even though the end of the electromagnetic spectrum boasts a huge bandwidth, i.e. of about 1022Hz , the waveforms tend to get highly distorted by a variety of interference sources such as environmental factors like dust, humidity etc.
In addition, sufficient exposure to very high frequency waves such as gamma rays, x-rays, and cosmic rays may prove to be detrimental for human health and hence are not preferred in communication technologies.
In order to best understand PSTN (Public Switched Telephone Networks), which is the most important part of telecommunication, let us compare it to the internet which is also based on the same physical infrastructure.
As the name indicates a PSTN includes devices such as telephones, fax machines, and circuit switches that help to establish temporary but uninterrupted connections. During the entire duration of the call, the circuit established between the two subscribers is kept open. Hence this provides a guaranteed and fail-safe quality of service. While PSTN has been specifically designed to provide optimum efficiency for voice calls, it utilizes the bandwidth rather inefficiently and hence the service tends to cost a tad more than the internet service.
The internet on the other hand serves by connecting networks rather than subscribers. As in PSTN the messages are routed to specific end devices, the same is true for internet, though the messages may be of any type and form ranging from e-mail to instant messaging to audio and video types.
As on the PSTN, messages on the Internet are routed to specific end devices. These messages take various forms, such as e-mail, instant messaging, and real-time audio/video communications. Unlike the PSTN, the internet works on packet data transfer and individual packets may vary their routes accordingly. The end user however, receives the packets in the same fashion as sent as the packets are rearranged at the destination.
Even though this means efficient utilization of the bandwidth, the quality of service is not the same as that of PSTN. Progress is being made on how to improve the quality of service of the internet.
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