The Mathematics of Mobile Networks

The mobile phones is used in our everyday life, the demand on mobile phone networks has increased steadily. Today, among other things like desktop laptops, mobile phones are used to access the internet, watch TV, read emails and use social media. The initial networks were designed to only transmit phone conversations. As technology improved, they had to be upgraded to deal with huge quantities of data. The Shannon-Hartley theorem is central to planning in the mobile phone industry. This formula relates the theoretical maximum bit-rate possible for a mobile phone user to the available bandwidth as licensed by the Government and the radio environment of the user. The radio environment of the user depends on a number of factors, most importantly the distance from the transmission tower, the power and frequency used by the transmission tower and the noise or interference from unwanted transmitters. In addition, it takes into account the ambient temperature of the day. Using this data, the mobile phone engineers are able to calculate the theoretical maximum bit-rate possible for information to be transmitted to the user. Then this result can then be compared with hardware limitations to evaluate the maximum transmission rate experienced by the user.


INTRODUCTION
The mobile network has improved lot as how the technology improves. Since when we started using the mobile phone many forgot about the post card, radio, calculator camera, watch etc., because they all are combined into the single MOBILE. So soon the mobile network was started as 2G, later developed into 3G and currently 4G network is ongoing. We have calculated the distance between bit-rate and transmission tower by using by using Shannon-Hartley Theorem.

CELL PLANNING ENGINEERING
Cell planning engineers work for all mobile phone companies in the country. Their aim is to ensure that we get good quality network coverage wherever we are. As a world leader in telecommunications equipment and data communication systems, Ericsson employs numerous engineers to research and study the latest technology and keep ahead of the competition.

MATHEMATICAL INFORMATION
Scientific notation is used for numbers which are too large or too small to be written using the standard decimal notation. For example, the distance between the Earth and the Sun is approximately 150,000,000 kilometers. This number has a lot of digits and will always be difficult to manipulate. Instead, it may be written using scientific notation in the form a × 10 b where a is a real number such that 1 ≤ |a| < 10 and the exponent b is an integer. In the present situation, the distance between the Earth and the Sun is 150,000,000 kilometers or 1.5 × 10 8 kilometers.

MULTIPLICATION AND DIVISION OF NUMBERS IN SCIENTIFIC NOTATION
Two numbers in scientific notation, x = a × 10 b and y = c × 10 d may be multiplied or divided as follows: x×y=(a×c) ×10 b+d ,
Ambient temperature: this is the temperature of the air surrounding us. It is measured in degrees Celsius, Fahrenheit or Kelvin.
Bit-rate: this represents the number of elementary blocks of information which can be transmitted during one second. Its unit is bits per second or bps.
Frequency: this is the number of times per second a radio wave reaches an antenna. Frequencies are measured in Hertz or Hz. Bandwidth: this is defined as the difference between the highest and the lowest frequencies in a radio signal, the unit is Hertz here again.

Example
Calculate the theoretical maximum bit-rate possible for a mobile phone user at a distance d = 5000 meters from the transmission tower on a 2G network using the Shannon-Hartley Theorem: Bit-rate= log(1+ ) where the constants are defined in the table 1.

Example 1
Evaluate the theoretical maximum bit-rate possible for a 4G (LTE) user using the Shannon-Hartley Theorem as a function of the distance d, between the user and the mobile phone transmission tower. Let us plot the graph from the above information which is representing the variation of the bit-rate as a function of the distance d on the grid paper.

Example 3
Using the curve from example 1, we work out up to what distance the maximum rate at which the transmission of information is limited by the hardware maximum bit-rate. Once this is done, we have evaluated the time it would take to download 1×10 9 bits of information when you are 10,000 meters away from the tower. Then evaluate the time would take to download 10×10 9 bits of information when you are 40,000 meters away from the tower.

Solution
The maximum rate at which information may be transmitted is provided by the Shannon-Hartley theorem and the limitations of the mobile phone. For a 4G mobile phone, the hardware maximum bit-rate is 1.5×10 8 bps. When the result provided by the Shannon-Hartley theorem is above this value, it should be substituted with 1.5 × 10 8 bps.
To determine at what distance from the tower it occurs, draw the line corresponding to 1.5 × 10 8 bits per second on the graph. It crosses the curve obtained using the Shannon-Hartley theorem at the distance d ≈ 25,000 metres. Therefore, when the distance to the tower is smaller than 25,000 metres, the maximum bit-rate at which information is transmitted is 1.5 × 10 8 bps. If the distance to the tower is above 25,000 metres, the maximum bit-rate at which information is transmitted is provided by the Shannon-Hartley theorem At d = 10,000 metres from the tower, the theoretical maximum bit-rate for a user as calculated with Shannon-Hartley theorem is 2.02 × 10 8 bps. This is above the hardware maximum bit-rate, so the bit-rate at which at which information is transmitted to the user is 1.5 × 10 8 bps.
At d = 40,000 metres from the tower, the theoretical maximum bit-rate for a user as calculated with Shannon-Hartley theorem is 1.22 × 10 8 bps. This is below the hardware maximum bit-rate, so the bit-rate at which information is trasmitted to the user is 1.22 × 10 8 bps.
Consequently, it takes t2 = To conclude, as suggested by the curve, the further away you are from the transmission tower, the longer it will take to download information. In the case considered here, the difference remains small, less than two seconds, which will hardly be noticed. When more complex formulas are used which include extra path losses and interference from other transmission towers and networks, this difference becomes more evident.

CONCLUSION
In this paper we have discussed the concept cell planning engineering & Shannon-Hartley theorem.
So the distance between bit-rate and transmission tower is calculated in order to calculate the mobile phone user by using 2G network of transmission tower from Shannon-Hartley theorem. In future 5G network may be applied to this concept, then the speed of mobile network may be increased, users may be increased. As the technology develops the usage of mobile phone is increased in the past 10 years. For the next 10 years the usage of mobile may be increased doubled than the past year.