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
