11th Class (HSSC-I) Computer SLO Based Key Point Notes

(National Book Foundation - As Federal Textbook Board, Islamabad 
Based on National Curriculum Pakistan 2023-2024 and Onward prescribed by Federal Board of Intermediate and Secondary Education, Islamabad, and All Pakistan Boards) 
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Unit 6: Wireless Communication


Q1. What is the Radio signal and transceiver?

Ans: 

Radio Signals: A radio signal is a type of electromagnetic wave that is propagated through the antenna and is received by the receiver based on frequency.

Transceiver: A Radio Transceiver is a device that has the capability of transmitting as well as receiving radio signals. In some types of radio transmission, the transmitter and receivers are housed as a single
circuitry e.g. Cell phones.


Q2. What is an RF system?

Ans: 

RF (Radio Frequency) System carries out communication using radio signals. It has two components, a transmitter to transmit signals and a receiver to receive signals. RF system defines some rules for communication such as matching of frequency.


Q3. What is a Wireless Access point (WAP)?

Ans: 

A Wireless Access Point is a device that connects wireless devices to a wired network. WAP is used in LAN to communicate using Wi-Fi.


Q4 What is meant by line-of-sight communication?

Ans: 

Line of Sight (LOS) Communication is a type of communication in which the transmitter and receiver are in sight of each other i.e. on the same line. These are used in high-frequency communication where signals cannot pass through obstacles like mountains or hills so are installed on high buildings, mountains, or towers.

Q5. Differentiate between short-distance and long-distance wireless communication?

Ans: 

Short Distance Wireless Communication

Long Distance Wireless Communication

This type of transmission covers a very small
geographical area i.e. up to 50km

This transmission covers a large area i.e. above
50km

This is inexpensive

This is expensive

Types are infra-red, Bluetooth, Wi-Fi, Wi-Max

Types are microwave and satellite
communications

Short-distance communication systems are
easy to install

Long-distance communication systems are
difficult to install

Short-distance communication systems are
easy to maintain

Long-distance communication systems are
difficult to maintain

Q6. What is a base station?

Ans: 

The base station is the main component of cellular or mobile communication that has a transceiver and controller to communicate with mobile devices. It facilitates mobile devices to communicate with each other.

Q7. Define global positioning system (GPS)

Ans: 

GPS (Global Positioning System) is a radio navigation system that determines the exact location of individuals, vehicles, ships, or airplanes on land, at sea, or in the air. It also studies the movement of tectonic plates by using relative positioning and time data.


Q8. What is Wireless Markup Language?

Ans: 

WML (Wireless Markup Language) is a language that is used to deliver internet content to small mobile devices having limited hardware and software. It is based on HTML and XML.


Q9. What is Wireless Application Protocol (WAP)?

Ans: 

Wireless Application Protocol (WAP) consists of various protocols that provide internet access to mobile users of wireless phones, pagers, and PDAs. Today, it has become a standard to provide data and voice services to hand-held mobile devices.


Q10. What is a Web Protocol Stack?

Ans: 

Web Protocol Stack consists of HTTP and TCP/IP. Its purpose is to allow two computers to communicate over the Internet. At the source device, text is converted to electronic signals to pass and at the destination computer electronic signals are converted back to text using the Web Protocol Stack.

Q11. What is HTTP

Ans: 

HTTP stands for Hyper Text Transfer Protocol which is an application protocol for the transmission of text and graphics on the World Wide Web. HTTP uses logical links (hyperlinks) between nodes containing text.

Q12. Write any three advantages of wireless communication.

Ans: 

  • No physical (wired) network is needed for wireless communication.
  • It can be easily carried out from any location i.e. no fixed location is required
  • It is Inexpensive for small mobile devices and PDAs.

Q13. Write any three disadvantages of wireless communication.

Ans: 

  • The main disadvantage is security breaches, hackers can easily tap into the network.
  • Speed can be slower because of low signals.
  • Signal strength is suffered as signals pass through the environment having trees, buildings, etc.

Q14. Define Wi-Fi communication

Ans: 

Wi-Fi stands for Wireless Fidelity, it is a high-speed wireless communication system used at LAN. It is secure inexpensive and easy to set but the limitation is the small coverage area due to low power signal.

Q15. Define Wi-Max communication

Ans: 

WI-Max stands for worldwide interoperability for Microwave Access. It provides public network services up to a range of 40-50 km. It creates MAN and provides a wireless alternative to Cable TV and DSL. It uses microwaves and more complex technology than Wi-Fi.

Q16. Define Bluetooth communication

Ans: 

Bluetooth is a short-range and low-speed communication technology. Its range is up to 10m and its speed is 723 Kbps, it consumes low power. It is used to exchange data between devices i.e. computers, mobile phones, game controllers, I/O devices, etc.

Q17. Define Infrared communication.

Ans: 

Infra-red waves are waves having a lower frequency than the visible range and higher wavelength. These are used for short-range communication. E.g. TV Remote Control, Car Locking system, Burglar alarm in home security systems, etc.

Q18. Define cellular communication.

Ans: 

Cellular communication is wireless communication that divides geographical ranges into sections called cells. Each cell has a BS (Base station) having a transceiver and a controller to provide radio communication to mobile phones.
 

Q19. Define GEO.

Ans: 

GEO stands for Geostationary Earth Orbit. It is directly above the Earth’s equator (at 0 latitude) at 35,786 km or 22000 miles with a period equal to the Earth’s rotational period. The satellites in this orbit are 3 in number at an angle of 1200 to each other and appear to be at a fixed position as seen from Earth. These are used for communication weather forecasting etc.

Q20. Define MEO.

Ans: 

MEO stands for Medium Earth Orbit. It is located above low earth orbit and below geostationary earth orbit i.e. at an altitude of 2000 km to 35,786 km. The satellites in this orbit are generally used for navigation such as GPS at 20,200 km. e.g. GLOBNASS at 19,100 km and GALILEO at 23,000 km.

Q21. Define LEO

Ans: 

LEO stands for Lower Earth Orbit. It is defined from 160 km to 2000 km above the earth's surface. Less energy is required to place satellites in LEO and low-power amplifiers are used for communication, therefore, most of the communication satellites are placed in this orbit e.g. International Space Station, the Space Shuttle, and the Hubble Space Telescope.

Q22. Compare LEO, MEO, and GEO.

Ans: 

 

LEO

MEO

GEO

Range

160 km to

2000 km

2000 km to 35786 km

35786 km

Orbital Period

10-40 minutes

2-8 Hours

24 Hours

Number of Satellites

40-80

8-20

3

Satellite Life

Short

Long

Long

Gateway Cost

Very Expensive

Expensive

Cheap

Number of handoffs

High

Low

Lease (None)

Uses

Communication

GPS

Weather forecasting

Q23. What is mobile communication? Name its components.

Ans: 

Mobile communication involves communication between mobile devices like mobile phones. It is achieved by cellular communication in which geographical regions are divided into sections called cells. Components of mobile communication are:
  • Mobile Phone
  • Base Station
  • Switching Node
  • Landline Telephone Network

Q24. Briefly explain all the components of the mobile communication system. (Long)

Ans: 

Mobile Phone: A mobile device that allows one to make and receive calls over a cellular network as well as use other services like SMS, MMS, etc.

Base Station: BS has a transceiver and a controller to provide radio communication to mobile phones. It is responsible for handling traffic and signaling between mobile phones.

Switching Node: The switching node, owned by mobile phone operators, allows mobile phones to communicate with each other and with the telephone landline network. It carries out switching and mobility management functions.

Landline Telephone Network: It is a wired Public Switched Telephone Network PSTN that connects a wireless mobile network to a landline telephone network.

Q25. Define the role of Base Station (BS) in mobile communication.

Ans: 

BS is located at the center of each cell. It has a transceiver and a controller to provide radio communication to mobile phones. It is responsible for handling traffic and signaling between mobile phones. It assigns a separate temporary radio frequency channel to each device which consists of two frequencies i.e. uplink frequency which the mobile phone uses to talk to BS and a downlink which BS uses to talk to the mobile phone.


Q26. Define uplink and downlink frequencies.

Ans: 

The communication channel within a cell in cellular communication consists of a pair of frequencies. Uplink frequency is used by mobile phones to talk to BS, and Downlink frequency is used by BS to talk to mobile phones.


Q27. What is the basic concept of cellular communication?

Ans: 

The basic concept of using cellular communication is that it reuses the radio frequency by the cells that are at a distance where there is no interference from the other.

Q28. What are the features of mobile communication

Ans: 

  • Mobile devices readily access information from the World Wide Web, the validity and accuracy cannot be guaranteed as anyone can upload any information without scrutiny.
  • Mobile users are frequently involved in copyright infringement while using information from the World Wide Web.
  • Daily use of mobile phones makes individuals dependent on mobile instead of their own potential.
  • Excessive use of mobile phones causes several diseases due to extensive and longer exposure to radio waves.

Q29. Write any three disadvantages of mobile communication.

Ans: 

  • Excessive use of mobile phones causes several diseases due to extensive and longer exposure to radio waves.
  • Mobile devices have smaller display screens, lower memory, and limited battery and CPU power.
  • Hackers can easily access mobile devices.


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