(SEM VII) THEORY EXAMINATION 2023-24 MOBILE COMPUTING

KCS711 – MOBILE COMPUTING

Section-wise Solved Answers

SECTION A (2 × 10 = 20 Marks)

Attempt all questions in brief

a) Mobile Computing

Mobile computing refers to the ability to access, process, and transmit data wirelessly using mobile devices such as smartphones, laptops, and tablets while moving.

b) Security Services offered by GSM

GSM provides the following security services:

Authentication                                                         Confidentiality

Anonymity                                                               Data encryption

c) Infrared

Infrared (IR) is a short-range wireless communication technology that uses infrared light waves for data transmission between devices.

d) Near and Far Problem

The near-far problem occurs when a near transmitter overpowers a far transmitter, causing interference in wireless communication systems.

e) Cache Consistency

Cache consistency ensures that cached copies of data remain up-to-date with the original data stored on the server.

f) Emulation

Emulation is the technique of imitating the functionality of one system on another, allowing software designed for one platform to run on a different platform.

g) D-AMPS

D-AMPS (Digital Advanced Mobile Phone System) is a digital cellular standard used mainly in North America.

h) Masquerade

Masquerade is a security attack in which an unauthorized user pretends to be an authorized user to gain system access.

i) Global State Routing

Global state routing is a routing technique where each node maintains complete information about the network topology.

j) Issues of QoS Routing

Some issues of QoS routing include:                        Bandwidth limitation

Node mobility                                                           Dynamic topology

Delay and packet loss

SECTION B (Attempt Any Three – 10 Marks Each)

a) Components of a Cellular System                         Mobile Station (MS)

Base Station Subsystem (BSS)                                   Network and Switching Subsystem (NSS)

Operation and Support Subsystem (OSS)

These components work together to provide seamless mobile communication.

b) MACA Protocol

MACA (Multiple Access with Collision Avoidance) is a MAC protocol designed to reduce collisions.

Hidden Node Problem:
Solved using RTS-CTS mechanism.

Exposed Node Problem:
Nodes refrain from unnecessary transmission based on RTS-CTS signals.

c) CODA File System

CODA is a distributed file system designed for mobile environments.

Clients of CODA:                                                            Mobile clients

Disconnected clients                                                        Weakly connected clients

d) Fault Tolerance in Mobile Computing

Fault tolerance ensures system reliability despite failures.

Techniques:                                                                    Replication

Checkpointing                                                                 Transaction recovery

Handoff management

e) Fisheye State Routing

FSR reduces routing overhead by maintaining detailed information for nearby nodes and less detail for distant nodes.

SECTION C (Attempt Any One – 10 Marks)

a) GSM Communication and History

GSM (Global System for Mobile Communication) was developed in the 1980s in Europe.

Features:                                                                      Digital communication

Roaming support                                                          Secure transmission

b) GPRS

Applications:                                                               Mobile internet

Multimedia messaging

Advantages:

Always-on connectivity                                                Packet-based billing

Disadvantages:

Low speed

Security concerns

SECTION D (Attempt Any One – 10 Marks)

a) IEEE 802.11 Standards                                              802.11a – 54 Mbps

802.11b – 11 Mbps                                                       802.11g – 54 Mbps

802.11n – High throughput                                          802.11ac – Very high speed

b) Mobile IP

Mobile IP allows mobile nodes to move across networks while maintaining the same IP address.

Components:                                                              Home Agent

Foreign Agent                                                              Care-of Address