What is Cellular System?
Cellular System sometimes also referred to as Cellular Wireless Network is a network which is composed of cells and offers radio telecommunication services to mobile devices. It is a high-capacity system that is designed to cover large geographical region and is known to be a revolutionary development in the field of data and telecommunications.
LTE is an example of cellular system, that connects multiple devices to a base station in order to establish communication.
Introduction to Cellular System
Cellular systems are not the first wireless systems however, the conventional wireless systems required high-power transmitter in order to cover the overall service area. To achieve this, great amount of power is need which is practically impossible.
The idea of cellular system came into existence after the operational limitations of conventional mobile telephone systems were seen. So, of the limitations are as follows:
- Poor service performance
- Frequency spectrum utilization is not sufficient
- Limited-service capability
Hence, a cellular system is an advancement of conventional system where the technology is used for mobile phones, personal communication systems, wireless networking, etc. This technology acts as replacement of high-power transmitter/receiver systems.
One should note here that some perks of cellular network over conventional system are lower power utilization factor, and data transmission ensures more transmission, etc.
Cellular Network Infrastructure
Till now we have got the basic definition of cellular system. A cellular system has the overall service region splitted into multiple cells. Each cell is served by a single transmitter. However, for effective channel utilization, transmitters that use low-power are used. By doing so, frequency can be reused even at smaller distances.
An efficient cellular system is said to be the one when each channel can be used at maximal times for a specific geographic region. It is known to be one of the significant changes in telecommunications industry.
Everyone of us is aware of the latest developments in internet technology and this has shown considerable rise in network technology thereby increasing the data rates. Due to this, the mobile technology changed and thus the mobile internet has grown in an extraordinary manner.
Earlier the large zone wireless communication systems were not divided into cells and so that were represented as:
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However, the cellular systems have replaced the large zone into various small cells having hexagonal shapes. Each cell has a single base station abbreviated as BS that covers that specific region. No matter what is the quantity of receivers present in the cell, the single BS serves each one of them.
The figure given below shows the representation of cellular system where the large zone is replaced by multiple small zones:
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The hexagonal shape of the cell is advantageous as it provides easy coverage and calculations. Not only this, in this arrangement, the antennas can be placed at equidistant regions.
This system works quite well as far as coverage is concerned along with that the locations that are not easily accessible by the wireless local area network is supported by cellular system.
One should note here that the wireless devices are used for multiple services and this device is generally given the name mobile station, abbreviated as MS. The mobile station can be wireless telephone, personal digital assistant, web enabled phone, etc.
In cellular system, the mobile station which is present in a specific cell makes communication with the base station of that cell. This supports the mobility of the mobile station.
For a large cellular system with multiple cells, various base stations are connected by hard-wires and all these are controlled by base station controller (BSC). The BSC forms connected with the mobile switching centre (MSC).
Features
- Some of the crucial features exhibited by cellular network are as follows:
- Even though the spectrum is limited, high capacity is obtained.
- It possesses the ability of frequency reuse also regarded as frequency planning.
- The interference is maintained under tolerable limits.
- Adequate communication is maintained between mobile and base station and no communication is made directly between any mobile devices.
- A fixed number of channels serve various users as channel is re-utilized over the entire coverage region.
- Power utilization is quite efficient as each cell has transmitter of only 100 W or even less.
Frequency Reuse
The concept of frequency reuse in cellular system allows the utilization of same radio frequency within a specific region. However, separation of considerable distance is mandatory to avoid interference and maintain communication.
Here a limited spectrum is used in such a manner that similar frequency can be used at multiple locations maintaining adequate distance. Have a look at the representation showing reusing the frequency in a cellular system:
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The adjacent cells are allocated different frequencies. In the above shown representation, the cluster size i.e., N is 4. This ‘N’ is nothing but the number of cells of same frequencies existing in a pattern. Not only this here ‘K’ is also an important denotation which corresponds to the total number of frequencies that the system is using.
There is a formula for calculating cell frequency which is given by K/N.
As we can clearly see over here that interference or crosstalk is avoided as no similar frequency is present in adjacent cells.
