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Part 1
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Part 6
1.What are
different categories of antenna and give an example of each?
2. What is
handover and what are its types?
3. What is
ionospheric bending?
4. What is CDMA?
5. Explain the
concept of frequency re-use.
6. Explain
Bluetooth.
What are different categories of antenna and give an example of each?
Different categories of antenna are as follows :
1. Wire Antennas - Short Dipole Antenna
2. Microstrip Antennas - Rectangular Microstrip (Patch) Antennas
3. Reflector Antennas - Corner Reflector
4. Travelling Wave Antennas - Helical Antennas
5. Aperture Antennas - Slot Antenna
6. Other Antennas - NFC Antennas
What is handover and what are its types?
Handover in mobile communication refers to the process of transferring a call
from one network cell to another without breaking the call.
There are two types of handover which are as follows :
Hard Handoff : hard handoff is the process in which the cell connection is
disconnected from the previous cell before it is made with the new one.
Soft Handoff : It is the process in which a new connection is established first
before disconnecting the old one. It is thus more efficient and smart.
What is ionospheric bending?
When a radio wave travels into the ionospheric layer it experiences refraction
due to difference in density. The density of ionospheric layer is rarer than
the layer below which causes the radio wave to be bent away from the normal.
Also the radio wave experiences a force from the ions in the ionospheric layer.
If incident at the correct angle the radio wave is completely reflected back to
the inner atmosphere due to total internal reflection. This phenomenon is
called ionospheric reflection and is used in mobile communication for radio
wave propagation also known as ionospheric bending of radio waves.
What is CDMA?
CDMA stands for Code Division Multiple Access which uses digital format. In CDMA
systems several transmissions via the radio interface take place simultaneously
on the same frequency bandwidth. User data is combined at the transmitter’s
side with a code, then transmitted. On air, all transmission get mixed. At the
receiver's side the same code is used as in the transmitter’s side. The code
helps the receiver to filter the user information of the transmitter from
incoming mixture of all transmissions on the same frequency band and same time.
Explain the concept of frequency re-use.
The whole of the geographical area is divided into hexagonal shape geometrical
area called cell and each cell having its own transceiver. Each BTS (cell site)
allocated different band of frequency or different channel. Each BTS antenna is
designed in such a way that i cover cell area in which it is placed with
frequency allotted without interfering other cell signals. The design process
of selecting and allocating channel groups for all of the cellular base station
within system is called frequency reuse.
Explain Bluetooth.
Bluetooth is designed to be a personal area network, where participating
entities are mobile and require sporadic communication with others. It is omni
directional i.e. it does not have line of sight limitation like infra red does.
Ericsson started the work on Bluetooth and named it after the Danish king
Harold Biuetooth. Bluetooth operates in the 2.4 GHz area of spectrum and
provides a range of 10 metres. It offers transfer speeds of around 720 Kbps.
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