FANET Architecture: Communication Types and Technologies

This article explores the architecture of FANETs (Flying Ad hoc Networks), a specialized subclass of MANETs (Mobile Ad hoc Networks). We will discuss the key elements of FANET communication architectures, including centralized and decentralized approaches, along with their interfaces.

What is a FANET?

As mentioned, a FANET is a specific type of MANET. Here’s a breakdown of its distinguishing characteristics:

• Node Mobility: Very High
• Node Speed:
  • RW-UAV (Rotor Wing UAV): Medium (around 50 Km/h)
  • FW-UAV (Fixed Wing UAV): High (around 100 Km/h)
• Mobility Model: Typically regular for predetermined paths, but can involve specialized models for autonomous multi-UAV systems.
• Node Density: Very Low
• Topology Change: Fast
• Radio Propagation Model: Line-of-Sight (LoS) is generally available in most scenarios.
• Power Consumption & Network Lifetime: Energy efficiency is crucial for mini-UAVs but less critical for larger UAVs.
• Computational Power: High
• Localization: GPS, AGPS, DGPS, and IMU (Inertial Measurement Unit) are commonly used for localization.

Image Credit: ResearchGate GmbH

FANET Architecture Overview

Image Courtesy: MDPI.com

A FANET typically comprises a swarm of small flying vehicles (UAVs) and a Ground Control Station (GCS).

• UAV Components: UAVs are equipped with cameras, GPS modules, and various sensors.
• Advantages of UAVs: UAVs provide long-range, Line-of-Sight communication and are resilient to diverse environmental conditions.
• Altitude Layers: UAVs can operate at different altitudes: low, medium, and high.

The high-altitude platform based FANET architecture demonstrates how UAVs perform two key tasks:

1. U2U Link (UAV-to-UAV): Establishing communication links with other UAVs in the network.
2. Network Information Collection and Relay: Gathering network information and relaying it to the infrastructure GCS via a U2I (UAV-to-Infrastructure) link.

Based on these roles, UAVs are categorized as:

• Member UAVs: These UAVs primarily collect data.
• Backbone UAVs: These UAVs collect data from member UAVs and relay it to the GCS.

FANET Communication Architectures

There are two main types of FANET architectures for connecting multiple UAVs: Centralized and Decentralized.

Centralized Architecture

In this architecture, the GCS acts as the central node. All UAVs connect directly to the GCS. Consequently, any data communication between two UAVs must pass through the GCS (Figure 3a).

Decentralized Architecture

In this architecture, UAVs can communicate directly with each other or indirectly through other UAVs. The decentralized architecture is further divided into three sub-types:

• UAV ad-hoc network (fig-3b)
• Multi-group UAV ad-hoc network (fig-3c)
• Multi-layer UAV ad-hoc network (fig-3d)

Types of Communication in FANET

• Inter-plane communication: Communication between UAVs on different altitude planes.
• Intra-plane communication: Communication between UAVs on the same altitude plane.
• Ground Station communication: Communication between UAVs and the ground station or base station.
• Ground Sensor communication: Communication between UAVs and ground-based sensors.

Wireless Technologies for FANET

The choice of wireless technology for a FANET depends on factors like mobility, range, data rate, latency, and network topology, as well as the specific application and mission requirements.

• Short-range communication: WiFi (802.11 series), Zigbee (802.15.4), Bluetooth (802.15.1), etc.
• Long-range communication: Satellite and cellular standards such as 2G (GSM), 3G (UMTS), 4G (WiMAX, LTE), and 5G.

Air-to-air (A2A) links are crucial for data delivery between UAVs, often utilizing heterogeneous radio interfaces like Zigbee and WiFi. Ground stations can function as stationary WSNs (Wireless Sensor Networks) and VANETs (Vehicular Ad hoc Networks) acting as control stations. UAV-to-WSN links can be used for collaborative sensing and data transfer.