IT6601 - Mobile Computing - 2 Marks Questions and Answers

1. Define Mobile computing.
Mobile computing as a generic term describing ability to use the technology to wirelessly connect to and use centrally located information and/or application software through the application of small, portable, and wireless computing and communication devices.

2. Difference between FDMA and TDMA.

FDMA	TDMA
Frequency Division Multiplexing Access is a method of dividing a single band into 30 discrete channels.	Time Division Multiplexing Access that also allows more subscribers to use the same frequency band.
Each channel would then be capable of handling separate traffic, whether it’s a call or a data transfer.	TDMA divides a single channel into 3 discrete time partitions.
FDMA is also used in the Total Access Communication System (TACS).	TDMA is utilized by Digital-Advanced Mobile Phone System (D-AMPS) and Global System for Mobile communications (GSM).

3.   Why do Hidden and Exposed terminal problem arise.
Hidden terminal problem is due to the fact that a node (say A) transmitting to another node (say B) cannot hear transmissions from another node C, which might also be transmitting to B, and might interfere with the A-to-B transmissions.
Exposed node problem occurs when a node is prevented from sending packets to other nodes because of a neighboring transmitter.

4.   Prove that Barker code has good auto correlation.
When the receiver attempts to correlate the received coded symbols with respect to any of the codes which it internally generates, it is not able to correlate even when it uses exactly the same code as the one used for transmission.
Reasons for no correlation
Propagation delay
Inappropriate code

5.   Write the characteristics of mobile computing.
•   Ubiquity
•   Location awareness
•   Adaptation
•   Broadcast
•   Personalization

6.   Draw the 3 Tier structure of Mobile computing application.

Presentation(Tire-1)

Application(Tier-2)

Data(Tier-3)

7.    State the issue in wireless MAC protocol.
•    Hidden Terminal Problem.
•    Exposed Terminal Problem.

8.    Draw the Taxonomy of MAC protocol.

9.    Write the different Random assignment scheme in MAC.
•    ALOHA
•    Slotted ALOHA
•    CSMA
•    CSMA/CD
•    CSMA/CA

10.    Difference between Mobile computing vs Wireless Networking.

Mobile computing	Wireless Networking
Mobile Computing denotes accessing information and remote computational services.	Wireless Networking provides the basic communication infrastructure.
It is based on wireless networking.	Wireless Networking is an important ingredient of mobile computing.

11.    Define mobile IP.
Mobile IP (or MIP) is an Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address.

12.    What is Tunneling process?
The encapsulation process creates a logical construct called a tunnel between the device that encapsulates and the one that decapsulates.

13.    Define COA.
A care-of address (usually referred to as CoA) is a temporary IP address for a mobile device. This allows a home agent to forward messages to the mobile device. A separate address is required because the IP address of the device that is used as host identification is topologically incorrect - it does not match the network of attachment. The care-of address splits the dual nature of an IP address, that is, its use is to identify the host and the location within the global IP network.

14.    State the features of mobile IP.
•    Transparency
•    Compatibility
•    Security
•    Efficiency and Scalability

15.    State the key mechanism used in Mobile IP.
•    Discovering the care-of-address
•    Registering the care-of-address
•    Tunnelling to the care-of-address

IT6601 - Mobile Computing - 2 Marks Questions and Answers

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