Сделай задания к тексту: 
Текст: For most of us, a mobile phone is a part of our lives. But many curious minds
have always been struck by such questions as how a mobile phone makes a call, and
why there are different generations of mobile communications? Let's explore the
technology behind mobile communications.
When you speak on your phone, your voice is picked up by your phone's
microphone. The microphone turns your voice into a digital signal with the help of
MEMS sensor and IC. The digital signal contains your voice in the form of zeros and
ones. An antenna inside the phone receives these zeros and ones and transmits them
in the form of electromagnetic waves. Electromagnetic waves transmit the zeros and
ones by altering the wave characteristics, such as the amplitude, frequency, phase, or
combinations of these. For example, in the case of frequency, zero and one are
transmitted by using low and high frequencies respectively. So, if you could find a
way to transmit these electromagnetic waves to your friend's phone, you would be
able to establish a call. However, electromagnetic waves are incapable of traveling
long distances. They lose their strength due to the presence of physical objects,
electrical equipment, and some environmental factors. In fact, if there were no such
issues, even then, electromagnetic waves would not carry on forever, due to the
Earth's curved structure. To overcome these issues, cell towers were introduced,
using the concept of cellular technology.
In cellular technology, a geographic area is divided into hexagonal cells with
each cell having its own tower and frequency slot. Generally, these cell towers are
connected through wires, or more specifically, optical fiber cables. These optical
fiber cables are laid under the ground or the ocean, to provide national or
international connectivity. The electromagnetic waves produced by your phone are
picked up by the tower in your cell and convert them into high frequency light pulses.
These light pulses are carried to the base transceiver box, located at the base of the
tower for further signal processing, after processing, your voice signal is routed
towards the destination tower. Upon receiving the pulses, the destination tower
radiates it outwards in the form of electromagnetic waves, and your friend's phone
then receives the signal. This signal undergoes a reverse process, and your friend
hears your voice. So, it's true that mobile communications are not entirely wireless,
they do use a wired medium too. This is how mobile communications are carried out.
However, there was a big issue that was intentionally left unanswered. Mobile
communication is only successful when your tower transfers the signal to your friend’s tower. But how does your tower know in which cell tower area your friend is
located? Well, for this process, the cell tower gets help from something called a
mobile switching center. The MSC is the central point of a group of cell towers.
Before moving further, let's explain more information about the MSC. When you
purchase a SIM card, all the subscription information is registered in a specified
MSC. This MSC will be your home MSC. The home MSC stores information such as
service plans, your current location, and your activity status. If you move outside the
range of your home MSC, the new MSC, which serves you instead, is known as a
foreign MSC. As you enter a foreign MSC region, it communicates with your home
MSC. In short, your home MSC always knows which MSC area you are in. To
understand in which cell location the subscriber is within the MSC area, the MSC
uses a few techniques. One way is to update the subscriber location after a certain
period. When the phone crosses a predefined number of towers, the location update is
again done. The last one of these is when the phone is turned on.
Let's try to understand all of these procedures with an example. Suppose,
Emma wants to call John. When Emma dials John's number, the call request arrives
at Emma's home MSC. Upon receiving John's number, the request will be forwarded
to John's home MSC. Now, John's MSC checks for his current MSC. If John is in his
home MSC, the call requests will be immediately sent to his current cell location, and
it checks whether John is engaged on another call, or if his mobile is switched off. If
everything is positive, John's phone rings, and the call will be connected. However, if
John is not in his home MSC, John’s home MSC simply forwards the call request to
the foreign MSC. The foreign MSC will follow the previously explained procedure to
locate John's phone, and will then establish the call.
Now, let's discuss why the frequency spectrum is quite important in mobile
phone communications. To transfer zeros and ones in digital communication, each
subscriber is allocated a frequency range. However, the frequency spectrum available
for cellular communications is quite limited, and there are billions of subscribers.
This issue is solved with the help of two technologies, one frequency slot distribution,
and two, multiple access technique. In the first technique, different frequency slots
are carefully allocated to different cell towers. In the multiple access technique, this
frequency slot is efficiently distributed amongst all the active users in the cell area.
Задания:
Task 2. Give the English equivalents of the following expressions:
Изменить характеристики волны, частота, соответственно, преодолеть проблемы, соты шестиугольной формы, преобразовать, световые импульсы,
обработка, абонент, запрос, выделить частоту.
Task 3. Answer the following questions.
1. How do electromagnetic waves transmit zeroes and ones?
2. Why are electromagnetic waves incapable of travelling long distances?
3. How is a geographic area organized in cellular technology?
4. Are mobile communications entirely wireless?
5. What is MSC? What is its function? What types of MSCs can you name?
6. What techniques does the MSC use to understand in which cell location
the subscriber is?
7. What is frequency slot distribution?
8. What is multiple access technique?
Task 4. Scan the text to mark the statements below true or false. If the
statements are false correct them.
1. An antenna inside the phone receives these zeros and ones and transmits
them in the form of bits.
2. Electromagnetic waves are capable of traveling long distances.
3. In cellular technology, a geographic area is divided into hexagonal cells.
4. The home MSC stores information such as service plans, your current
location, and your activity status.
5. If you move outside the range of your home MSC, the new MSC, which
serves you instead, is known as an outside MSC.
6. The frequency spectrum available for cellular communications is
unlimited.
7. In the multiple access technique, this frequency slot is efficiently
distributed amongst all the active users in the cell area.
Task 5. Find the right definition for the following words.
Frequency, IC, amplitude, phase, hexagonal, optical fiber, cell, MSC, radiate,
communication, subscriber, frequency slot distribution, multiple access technique,
allocate.