(SEM VII) THEORY EXAMINATION 2024-25 MOBILE COMPUTING

MOBILE COMPUTING (KCS711)

Time: 3 Hours | Maximum Marks: 100

SECTION A (10 × 2 = 20 Marks)

(Attempt all questions in brief)

1(a) Security services offered by GSM

GSM provides authentication, confidentiality of user data, confidentiality of signaling information, anonymity of subscriber identity, and protection against unauthorized access using encryption and authentication algorithms.

1(b) Differentiate between HLR and VLR

1(c) Mobile IP

Mobile IP allows a mobile node to maintain a permanent IP address while moving across different networks. It uses Home Agent, Foreign Agent, and Care-of Address to route packets.

1(d) Collisions on PHY vs MAC layer

PHY layer collisions occur due to signal interference.
MAC layer collisions occur when multiple nodes transmit simultaneously due to improper channel access.

1(e) Adaptive Clustering

Adaptive clustering dynamically forms and updates clusters based on node mobility, energy level, and network conditions to improve efficiency.

1(f) Masquerade

Masquerade is a security attack where an unauthorized user pretends to be an authorized user to gain access to network resources.

1(g) Hand over

Handover is the process of transferring an active call or data session from one base station or cell to another without interruption.

1(h) Functioning of a mobile agent in a network

A mobile agent migrates across network nodes, performs tasks locally, collects results, and returns to the originating node, reducing network load.

1(i) Global State Routing (GSR)

GSR is a proactive routing protocol for ad hoc networks where each node maintains global topology information and updates routing tables periodically.

1(j) Ad Hoc Networks

Ad hoc networks are decentralized wireless networks without fixed infrastructure, where nodes communicate directly and act as routers.

SECTION B (Attempt any THREE) (3 × 10 = 30 Marks)

2(a) Comparison of three generations of wireless telephone systems

1G: Analog, voice only, low security
2G: Digital (GSM), voice + SMS, better security
3G: High data rates, multimedia services, internet access

Applications evolved from voice calls to video calling, mobile internet, and streaming.

2(b) IEEE 802.11 standards

Includes 802.11a/b/g/n/ac/ax.
They differ in frequency band, data rate, modulation techniques, and range.
Later standards offer higher speed and better efficiency.

2(c) CODA file system & disconnected operations

CODA is a distributed file system supporting mobility.
Clients cache files locally and continue operations during disconnection.
Upon reconnection, updates are synchronized with conflict resolution.

2(d) Agent advertisement in packet forwarding

Agent advertisement informs mobile nodes about available foreign agents.
It includes agent address, lifetime, flags, and care-of address information.

2(e) QoS in mobile ad hoc networks

QoS parameters include bandwidth, delay, jitter, packet loss, and reliability.
Mobility, dynamic topology, and limited resources make QoS challenging.

SECTION C (Attempt any ONE) (10 Marks)

3(a) Comparison of SDMA, TDMA, FDMA, CDMA

3(b) GPRS architecture

GPRS is a packet-switched extension of GSM.
Components include SGSN, GGSN, BSS, and mobile station.
It enables internet access and higher data rates.