Mobile Computing and Networks (4351602) - Summer 2024 Solution

Question 1(a) [3 marks]

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Define Peer to Peer network

Answer: A Peer-to-Peer (P2P) network is a distributed network architecture where each node (peer) acts as both client and server, sharing resources directly without centralized control.

Table:

Mnemonic: “Peers Share Equally”

Question 1(b) [4 marks]

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Compare SMTP, POP and IMAP

Answer: Email protocols serve different purposes in email communication system.

Table:

Mnemonic: “Send-Pop-Internet Mail Access”

Question 1(c) [7 marks]

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Illustrate OSI model with responsibilities of each layer

Answer: The OSI (Open Systems Interconnection) model has seven layers, each with specific responsibilities for network communication.

Diagram:

graph TD
    A[Application Layer 7] --> B[Presentation Layer 6]
    B --> C[Session Layer 5]
    C --> D[Transport Layer 4]
    D --> E[Network Layer 3]
    E --> F[Data Link Layer 2]
    F --> G[Physical Layer 1]

Table:

Key Points:

• Application Layer: Provides network services to applications
• Transport Layer: Ensures reliable data delivery
• Network Layer: Handles routing between networks

Mnemonic: “All People Seem To Need Data Processing”

Question 1(c OR) [7 marks]

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Compare the TCP/IP model with OSI model

Answer: TCP/IP and OSI models are network architecture frameworks with different layer structures.

Diagram:

graph LR
    subgraph "OSI Model"
        O1[Application]
        O2[Presentation]
        O3[Session]
        O4[Transport]
        O5[Network]
        O6[Data Link]
        O7[Physical]
    end
    
    subgraph "TCP/IP Model"
        T1[Application]
        T2[Transport]
        T3[Internet]
        T4[Network Access]
    end

Table:

Key Points:

• OSI: Theoretical framework with detailed separation
• TCP/IP: Practical implementation for internet
• Mapping: Top 3 OSI layers = Application layer in TCP/IP

Mnemonic: “OSI Seven, TCP Four”

Question 2(a) [3 marks]

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Explain Network Address Translation (NAT)

Answer: NAT translates private IP addresses to public IP addresses, enabling multiple devices to share a single public IP.

Diagram:

Key Points:

• Purpose: IP address translation between networks
• Benefit: Conserves public IP addresses
• Security: Hides internal network structure

Mnemonic: “Network Address Translation”

Question 2(b) [4 marks]

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Define Subnetting and Supernetting

Answer: Subnetting and Supernetting are IP addressing techniques for efficient network management.

Table:

Key Points:

• Subnetting: Increases network bits, reduces host bits
• Supernetting: Decreases network bits, increases routing efficiency
• CIDR: Classless Inter-Domain Routing enables both

Mnemonic: “Sub-divides, Super-combines”

Question 2(c) [7 marks]

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Demonstrate Classful and Classless notation addressing scheme of IPv4

Answer: IPv4 addressing uses classful and classless schemes for network identification.

Table - Classful Addressing:

Classless (CIDR) Examples:

• 192.168.1.0/25: 128 hosts
• 10.0.0.0/16: 65,536 hosts
• 172.16.0.0/20: 4,096 hosts

Key Points:

• Classful: Fixed network/host boundaries
• Classless: Variable Length Subnet Mask (VLSM)
• CIDR: More efficient address allocation

Mnemonic: “Class-Fixed, CIDR-Flexible”

Question 2(a OR) [3 marks]

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Discuss goals of mobile IP

Answer: Mobile IP enables seamless connectivity for mobile devices across different networks.

Key Points:

• Transparency: Applications unaware of mobility
• Compatibility: Works with existing protocols
• Efficiency: Minimal routing overhead

Mnemonic: “Transparent Compatible Efficient”

Question 2(b OR) [4 marks]

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Define ARP and RARP

Answer: ARP and RARP are address resolution protocols for mapping between different address types.

Table:

Mnemonic: “ARP-asks, RARP-reverses”

Question 2(c OR) [7 marks]

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Demonstrate Stop and Wait, Stop and Wait ARQ data link layer protocols

Answer: These protocols ensure reliable data transmission at the data link layer.

Diagram - Stop and Wait:

sequenceDiagram
    participant S as Sender
    participant R as Receiver
    S->>R: Frame 0
    R->>S: ACK 0
    S->>R: Frame 1
    R->>S: ACK 1

Table:

Key Points:

• Stop and Wait: Send frame, wait for acknowledgment
• ARQ: Automatic Repeat reQuest on errors
• Timeout: Resend if no acknowledgment received

Mnemonic: “Stop-Wait-Acknowledge”

Question 3(a) [3 marks]

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Demonstrate Wireless networks

Answer: Wireless networks use radio waves for communication without physical connections.

Key Points:

• Technology: Radio frequency transmission
• Types: WiFi, Bluetooth, Cellular
• Benefits: Mobility, easy installation

Mnemonic: “Wireless-Radio-Mobile”

Question 3(b) [4 marks]

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Define Communication Middleware in mobile computing

Answer: Communication middleware provides abstraction layer for mobile application communication.

Table:

Mnemonic: “Middle-Communication-Layer”

Question 3(c) [7 marks]

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Discuss the architecture of Mobile Computing

Answer: Mobile computing architecture consists of multiple interconnected components supporting mobile applications.

Diagram:

graph TB
    A[Mobile Device] --> B[Wireless Network]
    B --> C[Base Station]
    C --> D[Mobile Support Station]
    D --> E[Fixed Network]
    E --> F[Database/Server]

Table:

Key Points:

• Three-tier: Mobile device, wireless network, fixed network
• Mobility Support: Handoff management
• Data Management: Caching and synchronization

Mnemonic: “Mobile-Wireless-Fixed”

Question 3(a OR) [3 marks]

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Demonstrate ad-hoc networks

Answer: Ad-hoc networks are self-organizing wireless networks without fixed infrastructure.

Key Points:

• Structure: Peer-to-peer topology
• Routing: Dynamic route discovery
• Applications: Emergency, military

Mnemonic: “Ad-hoc-Self-Organizing”

Question 3(b OR) [4 marks]

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Define Transaction Processing Middleware in mobile computing

Answer: Transaction processing middleware ensures ACID properties in mobile database transactions.

Table:

Mnemonic: “ACID-Properties”

Question 3(c OR) [7 marks]

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Discuss the applications and services of mobile computing

Answer: Mobile computing enables diverse applications across multiple domains.

Table:

Key Points:

• Location-based: GPS navigation, geo-fencing
• Communication: Email, messaging, video calls
• Commerce: Mobile banking, shopping

Mnemonic: “Business-Health-Education-Entertainment”

Question 4(a) [3 marks]

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Describe Indirect TCP in mobile computing

Answer: Indirect TCP splits TCP connection to handle mobile host mobility efficiently.

Diagram:

Key Points:

• Split Connection: Two separate TCP connections
• Base Station: Acts as proxy
• Advantage: Faster handoff

Mnemonic: “Indirect-Split-Proxy”

Question 4(b) [4 marks]

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Explain the steps of the packet delivery in Mobile IP

Answer: Mobile IP packet delivery involves registration, tunneling, and delivery steps.

Steps:

1. Registration: Mobile node registers with home agent
2. Tunneling: Home agent creates tunnel to foreign agent
3. Encapsulation: Original packet wrapped in new header
4. Delivery: Foreign agent delivers to mobile node

Mnemonic: “Register-Tunnel-Encapsulate-Deliver”

Question 4(c) [7 marks]

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Write following three processes of mobile IP: (1) Registration (2) Tunneling (3) Encapsulation

Answer:

1. Registration Process:

• Mobile node discovers foreign agent
• Registers care-of address with home agent
• Authentication and binding update

2. Tunneling Process:

• Home agent creates virtual tunnel
• Packets forwarded through tunnel
• Maintains end-to-end connectivity

3. Encapsulation Process:

• Original packet becomes payload
• New IP header added with care-of address
• Packet delivered to foreign network

Diagram:

graph LR
    A[Original Packet] --> B[Encapsulation]
    B --> C[Tunneled Packet]
    C --> D[Delivery]

Key Points:

• Registration: Location update mechanism
• Tunneling: Virtual connection establishment
• Encapsulation: Packet wrapping technique

Mnemonic: “Register-Tunnel-Encapsulate”

Question 4(a OR) [3 marks]

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Describe Snooping TCP in mobile computing

Answer: Snooping TCP improves performance by caching and monitoring TCP segments at base station.

Key Points:

• Local Retransmission: Base station handles losses
• Buffer Management: Caches unacknowledged segments
• Transparency: End-to-end TCP maintained

Mnemonic: “Snoop-Cache-Retransmit”

Question 4(b OR) [4 marks]

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Explain the Handover Management in mobile IP

Answer: Handover management maintains connectivity when mobile node changes networks.

Table:

Mnemonic: “Discover-Register-Forward-Cleanup”

Question 4(c OR) [7 marks]

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Write the goals and the requirements for the Mobile IP

Answer:

Goals:

• Transparency: Seamless mobility for applications
• Compatibility: Work with existing internet protocols
• Scalability: Support large number of mobile nodes
• Security: Authenticate mobile nodes and protect data

Requirements:

• Home Agent: Maintains mobile node location
• Foreign Agent: Provides local services
• Care-of Address: Temporary address in foreign network
• Tunneling: Packet forwarding mechanism

Table:

Mnemonic: “Transparent-Compatible-Scalable-Secure”

Question 5(a) [3 marks]

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Write the features of 6G in mobile networks

Answer: 6G represents the next generation of mobile networks with advanced capabilities.

Key Points:

• Speed: 1 Tbps theoretical speed
• Latency: Sub-millisecond latency
• AI Integration: Native artificial intelligence

Mnemonic: “Tera-Speed-AI-Integration”

Question 5(b) [4 marks]

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Describe Dynamic Host Configuration Protocol (DHCP)

Answer: DHCP automatically assigns IP addresses and network configuration to devices.

Table:

Mnemonic: “Discover-Offer-Request-Acknowledge”

Question 5(c) [7 marks]

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Describe the architecture of Wireless Personal Area Network (WLAN)

Answer: WLAN architecture provides wireless connectivity within local area using IEEE 802.11 standards.

Diagram:

graph TB
    A[Access Point] --> B[Distribution System]
    A --> C[Station 1]
    A --> D[Station 2] 
    A --> E[Station 3]
    B --> F[Internet/WAN]

Table:

Key Points:

• Infrastructure Mode: Uses access points
• Ad-hoc Mode: Direct device communication
• Standards: 802.11a/b/g/n/ac/ax protocols

Mnemonic: “Access-Station-Distribution”

Question 5(a OR) [3 marks]

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Write the features of 5G in mobile networks

Answer: 5G provides enhanced mobile broadband with ultra-low latency.

Key Points:

• Speed: Up to 10 Gbps download
• Latency: 1ms ultra-low latency
• Density: 1 million devices per km²

Mnemonic: “10G-1ms-1Million”

Question 5(b OR) [4 marks]

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Explain WWW and HTTP

Answer: World Wide Web uses HTTP protocol for web page communication.

Table:

Mnemonic: “Web-Hypertext-Transfer”

Question 5(c OR) [7 marks]

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Describe the architecture of Bluetooth

Answer: Bluetooth architecture provides short-range wireless communication using protocol stack.

Diagram:

graph TB
    A[Application Layer] --> B[OBEX/SDP]
    B --> C[L2CAP]
    C --> D[HCI]
    D --> E[Link Manager]
    E --> F[Baseband]
    F --> G[Radio Layer]

Table:

Key Points:

• Piconet: Master-slave network topology
• Frequency Hopping: 79 frequency channels
• Power Classes: Different transmission ranges

Mnemonic: “Radio-Baseband-Link-Host-Logic”