258  DTN Applications

258.1 Learning Objectives

By the end of this chapter, you will be able to:

  • Identify DTN Use Cases: Recognize scenarios where DTN provides unique value
  • Design Rural Connectivity: Apply DTN for developing region connectivity
  • Implement Wildlife Tracking: Use opportunistic forwarding for animal monitoring
  • Plan Hybrid Architectures: Combine infrastructure and DTN for robust systems
  • Evaluate Deployment Trade-offs: Balance latency tolerance against infrastructure costs

258.2 Prerequisites

Before diving into this chapter, you should be familiar with:

  • DTN Fundamentals: Understanding store-carry-forward is essential for application design
  • DTN Epidemic Routing: Knowledge of flooding-based routing helps understand when it’s appropriate
  • DTN Social Routing: Context-aware routing provides efficient alternatives for many applications

When to Use DTN:

  • Wildlife tracking (animals rarely meet)
  • Disaster recovery (infrastructure down)
  • Space networks (extreme delays)
  • Rural connectivity (intermittent access)

When NOT to Use DTN:

  • Video streaming (requires continuous connection)
  • Real-time gaming (cannot tolerate delays)
  • Emergency alerts (need immediate delivery)

Real Examples: - DakNet (India): Buses carry internet data to villages - 24h latency acceptable for email/queries - ZebraNet (Kenya): GPS collars on zebras exchange data when animals meet - 3-7 day latency acceptable for migration studies

DTN Series: - DTN Fundamentals - Store-carry-forward basics - DTN Epidemic Routing - Flooding-based protocols - DTN Social Routing - Context-aware and social-based routing

Applications: - IoT Application Domains - DTN use cases - Wildlife Tracking Examples - Real-world DTN

Architecture: - Wireless Sensor Networks - WSN in sparse deployments - UAV Networks - Aerial DTN applications - Mobile Phones as Gateway - Mobile DTN carriers

Learning: - Simulations Hub - DTN simulators

258.3 Applications of DTN Routing

⏱️ ~10 min | ⭐ Foundational | πŸ“‹ P04.C01.U05

258.3.1 Remote and Developing Regions

Scenario: Rural Agricultural Extension Service

%% fig-alt: "Rural connectivity DTN architecture showing three villages with Wi-Fi kiosks uploading queries to mobile bus during daily route, bus traveling to hub station with internet gateway to upload queries and download responses, and bus delivering answers back to villages on return route"
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graph LR
    V1[Village 1<br/>Wi-Fi Kiosk] -.Upload Queries.-> Bus[Mobile Bus<br/>Wi-Fi + Storage]
    V2[Village 2<br/>Wi-Fi Kiosk] -.Upload Queries.-> Bus
    V3[Village 3<br/>Wi-Fi Kiosk] -.Upload Queries.-> Bus

    Bus -->|Daily Route| Hub[Hub Station<br/>Internet Gateway]
    Hub -->|Download Responses| Bus

    Bus -.Deliver Answers.-> V1
    Bus -.Deliver Answers.-> V2
    Bus -.Deliver Answers.-> V3

    style V1 fill:#2C3E50,stroke:#16A085,color:#fff
    style V2 fill:#2C3E50,stroke:#16A085,color:#fff
    style V3 fill:#2C3E50,stroke:#16A085,color:#fff
    style Bus fill:#E67E22,stroke:#16A085,color:#fff
    style Hub fill:#16A085,stroke:#2C3E50,color:#fff

Figure 258.1: Rural connectivity DTN architecture showing villages with Wi-Fi kiosks, mobile bus carrier, and hub station with internet gateway.

Operation: - Villages have Wi-Fi kiosks but no internet - Farmers submit queries (crop prices, weather, health questions) - Bus with Wi-Fi node drives daily route - Bus collects queries from villages - At hub, bus uploads queries to internet gateway - Responses downloaded to bus - Bus delivers responses on return route

Real Implementation: DakNet (2003), India - Latency: 24-48 hours (acceptable for non-urgent queries) - Cost: Extremely low (reuses existing bus routes) - Impact: Thousands of rural users connected

258.3.2 Military Tactical Networks

Challenged Environment: - No infrastructure - Jamming and interference - High mobility - Intermittent connectivity - Hostile territory

DTN Solution: - Soldiers carry handheld DTN nodes - Vehicles act as mobile relays - UAVs provide aerial data mules - Opportunistic forwarding when in range - Store-and-forward tolerates disconnections

258.3.3 Sensor Systems

Wildlife Tracking Example:

%% fig-alt: "Wildlife tracking DTN showing three zebras with GPS collars opportunistically exchanging movement data when encountering each other, with zebra 3 delivering accumulated weeks of data and movement patterns to watering hole base station, which uploads to research database cloud"
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graph TD
    Z1[Zebra 1<br/>GPS Collar] -.Opportunistic.-> Z2[Zebra 2<br/>GPS Collar]
    Z2 -.Exchange Data.-> Z3[Zebra 3<br/>GPS Collar]
    Z3 --> WH[Watering Hole<br/>Base Station]
    Z1 -.Weeks of Data.-> WH
    Z2 -.Movement Patterns.-> WH

    WH --> Cloud[Research<br/>Database]

    style Z1 fill:#E67E22,stroke:#16A085,color:#fff
    style Z2 fill:#E67E22,stroke:#16A085,color:#fff
    style Z3 fill:#E67E22,stroke:#16A085,color:#fff
    style WH fill:#16A085,stroke:#2C3E50,color:#fff
    style Cloud fill:#2C3E50,stroke:#16A085,color:#fff

Figure 258.2: Wildlife tracking DTN showing zebras with GPS collars opportunistically exchanging movement data and delivering to base station.

ZebraNet (2002): - GPS collars on zebras - Collect location/movement data - Store locally for weeks - Transfer opportunistically when zebras encounter each other - Download to base station when animals visit watering hole - Battery budget: ~3 years

DTN Benefits: - No need to track every animal continuously - Data eventually reaches base station - Ultra-low power (mostly storage, rare transmissions)

258.3.4 Hybrid Models

Modern IoT deployments often combine infrastructure and DTN:

Smart City Hybrid:

%% fig-alt: "Hybrid smart city architecture showing infrastructure zone with sensors connected via Wi-Fi to gateway and fiber to cloud, coverage gap zone with remote sensors using DTN store-carry-forward via mobile collector, and backup path with sensors using DTN fallback when primary infrastructure fails"
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graph TD
    subgraph "Infrastructure Zone"
        S1[Sensor 1] -->|Wi-Fi| GW1[Gateway]
        S2[Sensor 2] -->|Wi-Fi| GW1
        GW1 -->|Fiber| Cloud[Cloud<br/>Platform]
    end

    subgraph "Coverage Gap"
        S3[Remote<br/>Sensor] -.DTN Store.-> Mobile[Mobile<br/>Collector]
        S4[Remote<br/>Sensor] -.DTN Carry.-> Mobile
    end

    Mobile -->|Deliver| GW1

    subgraph "Backup Path"
        S5[Sensor 5] -.DTN Fallback.-> S6[Sensor 6]
        S6 -.Store-Forward.-> GW2[Gateway 2]
    end

    GW2 --> Cloud

    style S1 fill:#2C3E50,stroke:#16A085,color:#fff
    style S2 fill:#2C3E50,stroke:#16A085,color:#fff
    style GW1 fill:#16A085,stroke:#2C3E50,color:#fff
    style Cloud fill:#2C3E50,stroke:#16A085,color:#fff
    style S3 fill:#E67E22,stroke:#16A085,color:#fff
    style S4 fill:#E67E22,stroke:#16A085,color:#fff
    style Mobile fill:#E67E22,stroke:#16A085,color:#fff

Figure 258.3: Hybrid smart city architecture showing infrastructure zone, coverage gap with DTN, and backup paths.

Why Hybrid? - Infrastructure where available (low latency, high bandwidth) - DTN for coverage gaps (no infrastructure cost) - Mobile nodes bridge gaps - Graceful degradation (DTN fallback if infrastructure fails)

258.3.5 Space Networks

Interplanetary Communication: - Light-speed delays: Mars is 4-24 minutes away - Planetary occlusion: No line-of-sight during planet rotation - Relay satellite handoffs - Bundle Protocol (RFC 5050) standardizes DTN for space

NASA Deep Space Network: - Uses DTN principles for Mars rovers - Store data during blackouts - Forward when Earth visible - Tolerates hours of disconnection

258.3.6 Disaster Recovery

Post-Disaster Scenarios: - Cell towers destroyed - Power grid down - Roads blocked - First responders need communication

DTN for Disaster Response: - Responders carry DTN nodes - Drones provide aerial relay - Survivor phones act as DTN nodes - Messages eventually reach command center - Better than no communication

258.4 Knowledge Check

Question: In a wildlife tracking DTN, collar A encounters collar B (contact duration 45s). Collar A has 3 messages (each 50KB) to forward. At 500Kbps, can all messages be transferred?

Explanation: Data size: 3 messages x 50KB = 150KB = 150 x 8 = 1200 Kb (kilobits). Transfer time: 1200 Kb / 500 Kbps = 2.4 seconds. Available time: 45 seconds. Verdict: Easily fits with 42.6s spare. Practical overhead: Connection setup (3s), protocol handshake (2s), actual transfer (2.4s) = ~7.5s total (still well under 45s). Real constraint: Buffer capacity - if collar B’s buffer is full, messages queue. DTN optimization: Prioritize urgent messages (animal vitals) over routine data (GPS positions), bundle similar messages (combine 3x50KB into 1x150KB packet for efficiency). This demonstrates DTN’s ability to exploit brief opportunistic contacts.

258.5 Application Selection Guide

Use DTN When:

Table 258.1: DTN Application Suitability Guide
Scenario Latency Tolerance DTN Suitable?
Wildlife tracking Days-weeks Yes
Rural health records Hours-days Yes
Disaster messaging Minutes-hours Yes
Environmental monitoring Hours Yes
Video streaming Milliseconds No
Real-time control Milliseconds No
Financial transactions Seconds No
Voice calls Milliseconds No

Decision Framework:

Is continuous connectivity available?
β”œβ”€β”€ Yes β†’ Use traditional networking
└── No β†’ Can application tolerate delay?
    β”œβ”€β”€ No β†’ Invest in infrastructure or satellite
    └── Yes β†’ How much delay?
        β”œβ”€β”€ Minutes β†’ Epidemic routing (high delivery)
        β”œβ”€β”€ Hours β†’ Context-aware routing (balanced)
        └── Days β†’ Social routing (efficient)

258.7 Summary

This chapter covered real-world DTN applications and deployment scenarios:

  • Rural Connectivity: DakNet-style systems use buses or vehicles as data mules to connect villages without infrastructure, accepting 24-48 hour latency for email and information queries
  • Wildlife Tracking: ZebraNet demonstrates opportunistic data collection from animals using GPS collars that exchange data when animals encounter each other, with 3-7 day acceptable latency
  • Military Tactical: Soldiers, vehicles, and UAVs form DTN networks in infrastructure-free hostile environments with jamming and high mobility
  • Space Networks: NASA’s Deep Space Network uses DTN principles (Bundle Protocol) to handle light-speed delays and planetary occlusion for Mars communication
  • Disaster Recovery: Post-disaster scenarios leverage responder nodes, drones, and survivor phones for communication when infrastructure is destroyed
  • Hybrid Architectures: Modern deployments combine infrastructure (low latency) with DTN (coverage gaps and fallback), using mobile collectors to bridge disconnected areas
  • Application Selection: DTN is suitable when applications can tolerate minutes-to-days latency; unsuitable for real-time streaming, voice, or financial transactions

258.8 What’s Next

This concludes the DTN series. Continue with Ad Hoc Labs and Quiz for hands-on DTN implementation exercises, or explore Ad Hoc Production and Review for protocol comparisons and production considerations.