448  UAV Network Topologies

448.1 Learning Objectives

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

• Compare Star and Mesh Topologies: Analyze the advantages and disadvantages of centralized vs distributed UAV network configurations
• Design Multi-Hop Networks: Plan relay-based UAV networks for extended coverage in challenging terrain
• Select Appropriate Topology: Choose the right network topology based on mission requirements, swarm size, and resilience needs
• Calculate Relay Requirements: Determine the number of relay UAVs needed for a given coverage area and communication range

448.2 Prerequisites

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

• UAV Introduction: Basic UAV network concepts and FANET fundamentals
• UAV Network Features: Understanding core capabilities and challenges of UAV networks

448.3 UAV Network Topologies

Time: ~10 min | Intermediate | P05.C22.U03

448.3.1 Star Topology

Figure 448.1: UAV star topology with central ground control station coordinating multiple drones

UAV Star Topology

Figure 448.2: UAV star topology visualization showing centralized control architecture with all communications flowing through the ground station.

In star topology, UAVs communicate directly with a ground control station (GCS) or through designated hub UAVs.

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graph TB
    subgraph "UAV Star Topology"
        GCS["Ground Control<br/>Station<br/>(Central Hub)"]

        UAV1["UAV 1"]
        UAV2["UAV 2"]
        UAV3["UAV 3"]
        UAV4["UAV 4"]
        UAV5["UAV 5"]

        GCS <-->|Command/Control| UAV1
        GCS <-->|Telemetry| UAV2
        GCS <-->|Mission Data| UAV3
        GCS <-->|Status Updates| UAV4
        GCS <-->|Video Feed| UAV5

        Note["All UAV-to-UAV communication<br/>must go through GCS"]
    end

    style GCS fill:#2C3E50,stroke:#16A085,color:#fff
    style UAV1 fill:#E67E22,stroke:#2C3E50,color:#fff
    style UAV2 fill:#E67E22,stroke:#2C3E50,color:#fff
    style UAV3 fill:#E67E22,stroke:#2C3E50,color:#fff

Figure 448.3: UAV Star Topology showing Ground Control Station as central hub with bidirectional communication links to 5 UAVs. {fig-alt=“UAV Star Topology showing Ground Control Station as central hub with bidirectional communication links to 5 UAVs (command/control, telemetry, mission data, status updates, video feed), with note that all UAV-to-UAV communication must go through GCS creating simple but centralized architecture”}

Advantages: - Simple communication model - Easy coordination from GCS - Reduced inter-UAV interference

Disadvantages: - High latency (everything through GCS) - Single point of failure (GCS dependency) - Limited scalability - No local communication between UAVs

Use Cases: - Small swarms (< 10 UAVs) - Surveillance missions with central monitoring - Agricultural mapping

InlineKnowledgeCheck_kc_uav_topology_1 = ({
  question: "A city police department wants to deploy 4 UAVs for real-time traffic monitoring during a marathon. Each UAV covers a 2 km section of the 8 km route, streaming live 1080p video (5 Mbps per stream) to the command center. The route passes through areas with tall buildings that block direct line-of-sight between some UAV positions and the command center. Which topology should they use?",
  options: [
    "Star topology with all UAVs connecting directly to the command center's high-power ground station",
    "Mesh topology with UAVs relaying video through adjacent UAVs if direct command center link fails",
    "Hierarchical topology with UAV-1 and UAV-4 at route ends acting as master nodes",
    "Hybrid topology with two separate star networks (UAVs 1-2 and UAVs 3-4) each with local ground stations"
  ],
  correctAnswer: 1,
  feedback: {
    correct: "Perfect choice! Mesh topology with multi-hop relay is ideal for urban line-of-sight challenges. Tall buildings create RF shadows that block direct paths between UAVs and command center. In mesh topology, if UAV-2's direct link is blocked by a skyscraper, it automatically routes video through UAV-1 or UAV-3 toward the command center. Mesh routing protocols automatically recalculate best paths as UAVs move along the route.",
    incorrect: [
      "Star topology would be simplest if line-of-sight was guaranteed, but urban buildings make direct links unreliable. A skyscraper between UAV-2 and command center creates a Fresnel zone obstruction. Even high-power ground stations can't overcome geometric blockage at 2.4-5.8 GHz frequencies.",
      "Hierarchical topology with master nodes at route ends creates unnecessary complexity and doesn't solve the line-of-sight problem. If buildings block the master nodes, the hierarchy collapses.",
      "Hybrid topology with two separate star networks partitions the surveillance into disconnected systems, creating coordination problems at the boundary."
    ]
  },
  difficulty: "medium",
  learningObjective: "Select appropriate UAV network topology based on environment constraints and mission requirements"
})

448.3.2 Mesh Topology

NoteWorked Example: Multi-Hop Mesh Network for Search and Rescue

Scenario: A search and rescue team deploys 8 UAVs to find a missing hiker in a mountainous valley. The valley is 12 km long but only 2 km wide, with steep terrain blocking direct line-of-sight communication to the command post at the valley entrance.

Given: - 8 UAVs with 2 km air-to-air communication range - Command post at valley entrance (km 0) - Search area: km 2 to km 12 (10 km length) - Required: Real-time video relay from any search UAV to command post - Data rate needed: 5 Mbps per active video stream - Maximum latency tolerance: 500 ms

Steps: 1. Calculate relay UAV spacing: With 2 km range, space relay UAVs at 1.8 km for reliable links (10% margin). Coverage from km 0 to km 12 requires: 12 km / 1.8 km = 7 relay positions (including command post link) 2. Allocate UAVs to roles: Need 6 relay UAVs to form backbone (km 1.8, 3.6, 5.4, 7.2, 9.0, 10.8). Remaining 2 UAVs serve as mobile search units with thermal cameras 3. Calculate maximum hop count: Farthest search point (km 12) to command (km 0): Data travels through 6 relay UAVs + 1 hop to search UAV = 7 hops maximum 4. Verify latency: Each hop adds approximately 50 ms (processing + transmission). Total: 7 x 50 ms = 350 ms < 500 ms requirement (passed) 5. Verify bandwidth: 5 Mbps video through 7 hops. Each relay handles up to 2 search UAVs streaming simultaneously. Relay capacity: 54 Mbps (802.11a). 2 x 5 Mbps = 10 Mbps much less than 54 Mbps (passed) 6. Calculate network resilience: With mesh topology, if relay at km 5.4 fails, UAVs at km 3.6 and km 7.2 can communicate directly (3.6 km apart, slightly exceeds 2 km range). Single point of failure exists - recommend adding 1 redundant relay

Result: A 6-relay backbone with 2 mobile search UAVs provides continuous video connectivity across the 12 km valley with 350 ms latency.

Key Insight: Mesh topology’s resilience depends on link redundancy. In constrained geometries (valleys, corridors), the mesh may degrade to a near-linear chain with limited alternate paths.

Figure 448.4: UAV mesh topology enabling resilient multi-hop aerial communication

In mesh topology, UAVs communicate peer-to-peer, forming a fully or partially connected network.

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graph TB
    subgraph "UAV Mesh Topology"
        UAV1["UAV 1"]
        UAV2["UAV 2"]
        UAV3["UAV 3"]
        UAV4["UAV 4"]
        UAV5["UAV 5"]

        UAV1 <-.->|Peer-to-Peer| UAV2
        UAV1 <-.->|Peer-to-Peer| UAV3
        UAV1 <-.->|Peer-to-Peer| UAV4
        UAV2 <-.->|Peer-to-Peer| UAV3
        UAV2 <-.->|Peer-to-Peer| UAV5
        UAV3 <-.->|Peer-to-Peer| UAV4
        UAV3 <-.->|Peer-to-Peer| UAV5
        UAV4 <-.->|Peer-to-Peer| UAV5

        GCS["Ground Control<br/>Station<br/>(Optional)"]
        UAV1 -.->|Reporting| GCS
        UAV5 -.->|Reporting| GCS

        Note["Multiple redundant paths<br/>Distributed decision-making<br/>Self-healing network"]
    end

    style UAV1 fill:#2C3E50,stroke:#16A085,color:#fff
    style UAV3 fill:#E67E22,stroke:#2C3E50,color:#fff
    style UAV5 fill:#16A085,stroke:#2C3E50,color:#fff
    style GCS fill:#7F8C8D,stroke:#2C3E50,color:#fff

Figure 448.5: UAV Mesh Topology showing 5 UAVs with peer-to-peer bidirectional links forming fully connected mesh network. {fig-alt=“UAV Mesh Topology showing 5 UAVs with peer-to-peer bidirectional links forming fully connected mesh network, optional Ground Control Station receives reporting from 2 UAVs, highlighting multiple redundant paths, distributed decision-making, and self-healing network capabilities for resilience”}

Advantages: - Resilient to node failures - Multi-path routing options - Local communication without GCS - Scalable

Disadvantages: - Complex routing protocols - Higher energy consumption (more transmissions) - Coordination challenges

Use Cases: - Large swarm operations - Search and rescue (redundancy needed) - Distributed sensing missions

UAV Mesh Network

Figure 448.6: UAV mesh network visualization showing resilient peer-to-peer connectivity with multiple communication paths.

448.3.3 Topology Comparison

Standard View

UAV Topology Comparison - Standard quality PNG format

High Quality (SVG)

UAV Topology Comparison - Scalable SVG format for high resolution

Figure 448.7: Comparison of UAV network topologies - star, mesh, and hybrid configurations

Aspect	Star	Mesh
Complexity	Low	High
Scalability	Limited (< 20 UAVs)	High (100+ UAVs)
Latency	High (via GCS)	Low (direct paths)
Resilience	Low (GCS failure critical)	High (multi-path)
Energy	Moderate	Higher
Coordination	Centralized (easy)	Distributed (complex)
Use Case	Small missions	Large swarms, resilience needed

448.4 Knowledge Check

NoteQuiz: UAV Topologies

Question 1: In a FANET, 5 UAVs must collect data from 100 ground sensors spread over 5 km squared. What’s the optimal UAV deployment strategy?

Explanation: Swarm coordination for efficient coverage means dividing the area enables parallel operation - all zones collected simultaneously (5x faster than sequential). Each UAV covers smaller area (1 km squared), reducing flight distance and energy consumption. Multi-hop networking extends effective communication range beyond single UAV’s radio. Redundancy ensures if one UAV fails, others still operate.

Question 2: UAVs can operate in star topology (all communicate with central UAV) or mesh topology (peer-to-peer). What determines which topology to use?

Explanation: Star topology offers simple routing, centralized control, and easier conflict resolution, but has single point of failure and limited scalability. Use for 3-5 UAVs where mission requires tight coordination. Mesh topology provides no single point of failure, distributed load, and scales better for 10+ UAVs and large areas where resilience is critical.

InlineKnowledgeCheck_kc_uav_topology_2 = ({
  question: "A telecommunications company wants to provide temporary 4G LTE coverage to a music festival with 50,000 attendees in a remote desert location. They plan to use UAVs as aerial base stations. The festival grounds are 2 km by 1 km. Which deployment strategy would provide the best coverage?",
  options: [
    "Deploy 1 large UAV at 500 m altitude carrying high-power macro cell equipment (50 kg payload)",
    "Deploy 4 medium UAVs at 200 m altitude, each covering a 1 km by 0.5 km quadrant with small cell equipment",
    "Deploy 10 small UAVs at 100 m altitude in a mesh network, each carrying femtocell equipment",
    "Deploy 2 tethered UAVs at 300 m altitude with unlimited flight time via ground power cables"
  ],
  correctAnswer: 1,
  feedback: {
    correct: "Excellent deployment strategy! Four medium UAVs at 200 m forming sectored coverage is optimal. Capacity per cell: 50,000 users divided by 4 UAVs = 12,500 users per cell. Modern LTE small cells handle 10,000-15,000 concurrent users with QoS. At 200 m altitude, each UAV provides approximately 1.5 km diameter coverage. This also provides redundancy if one UAV fails.",
    incorrect: [
      "A single large UAV at 500 m seems attractive but faces critical capacity limitations. LTE macro cells serve 5,000-10,000 concurrent users maximum. 50,000 festival attendees creates 5-10x overload causing massive call drops.",
      "Ten small UAVs with femtocell equipment introduces excessive handoff overhead and backhaul bottleneck. Users crossing cell boundaries every 200-300 meters causes video buffering and call interruptions.",
      "Tethered UAVs solve battery endurance but create operational limitations. At 300 m altitude, tether cable must be more than 350 m long. Such cable weighs 40-60 kg, exceeding small UAV lift capacity."
    ]
  },
  difficulty: "hard",
  learningObjective: "Design UAV deployment strategies for aerial base station applications considering capacity, coverage, and operational constraints"
})

448.5 Summary

This chapter examined UAV network topologies and their applications:

• Star Topology: Centralized architecture with simple coordination but single point of failure, suitable for small swarms (< 10 UAVs) with central monitoring requirements
• Mesh Topology: Distributed peer-to-peer architecture providing resilience and scalability for large swarms (100+ UAVs) and missions requiring redundancy
• Topology Selection: Choose based on swarm size, resilience requirements, area coverage, and coordination complexity
• Multi-Hop Planning: Calculate relay spacing, hop count, and latency to ensure coverage in challenging terrain
• Trade-offs: Star offers simplicity and low energy; mesh offers resilience at cost of complexity and energy consumption

448.6 What’s Next

The next chapter explores UAV Swarm Coordination, examining how multiple UAVs work together using distributed algorithms for task allocation, formation control, and cooperative mission execution.

Continue to UAV Swarm Coordination