With a mesh network you can communicate without mobile connection

During certain protests in Hong Kong, the government shut down the local mobile network, making it more difficult for demonstrators to organise themselves. However, through a simple app that works via a ‘mesh network’, they were still able to communicate, even though they had no network connection. Such a network therefore forms a handy alternative for communicating with each other at short distances when no central infrastructure is available.

How does it work?

A mesh network consists of multiple nodes that connect with each other and forward messages to their final destination. Whilst traditional networks depend on central transmitter masts, each device in a mesh network can function as a relay station.

Different forms of mesh communication

There are various forms of communication that work via a mesh network. Below we list some well-known products.

Meshtastic: open-source mesh communication

Meshtastic is a project that makes it possible to use inexpensive LoRa radios as an off-grid communication platform in areas without existing or reliable communication infrastructure.

💡 Did you know, by the way, that some smartphones can communicate via satellites in emergencies and without network connection?

This project is 100 per cent community-driven and open source. The system uses the 868 MHz frequency band in Europe, a licence-free band that may be used by everyone.

Technical specifications:

• Energy consumption: Extremely low through use of LoRa technology
• Frequency: 868 MHz (Europe), other bands for other regions
• Range: Up to 4.8 km in urban areas and up to 16 km or more in rural areas (with clear line of sight)
• Data rate: 0.3 to 27 kbit/s depending on the spreading factor

Hardware and costs:

A commonly used LoRa set that is compatible with Meshtastic is that from Heltec – available for purchase for approximately 25 euros. The kit is virtually complete – for this money you receive an ESP32 board with LoRa support, a housing and antenna. For people who want to build themselves, there are more extensive options with different antennas, housings and power supply options.

Popular options:

• LoRa 32 V3: complete starter kit
• RAK WisBlock modules: Modular system for customised applications
• T-Beam modules: Built-in GPS for location sharing

Professional mesh systems

Commercial suppliers such as Ubiquiti and Cambium Networks offer robust mesh solutions for professional use. These systems have greater range and better performance, but cost considerably more than hobby solutions.

Smartphone-based mesh apps: FireChat as an example

FireChat was a mobile app that received much attention between 2014 and 2018 as a smartphone-based mesh solution. The app made use of WiFi and Bluetooth radios in smartphones to pass messages from phone to phone, without internet connection or mobile networks.

Technical operation of FireChat:

• Used WiFi Direct, Bluetooth and Apple’s Multipeer Connectivity
• Range of approximately 70 metres between individual phones
• Messages were forwarded via a chain of devices
• Worked cross-platform between Android and iOS

FireChat became known worldwide during the protests in Hong Kong in 2014, when demonstrators downloaded the app 100,000 times in 24 hours. Also during protests in Taiwan, Iraq, Syria and Ecuador, activists saw the value of independent communication. In September 2015, FireChat was used 131,000 times during the pro-independence demonstrations in Catalonia.

Practical applications

Where mesh networks excel

Meshtastic can be handy in various situations, such as outdoor sporting activities like trekking, camping, walking, cycling… Also during emergencies such as natural disasters, power cuts or other crisis situations, the technology has already proved its usefulness. In the United States, there are local authorities, such as Jefferson County in Colorado, that use it to support first responders.

Proven applications:

• Outdoor events and festivals where mobile networks become overloaded
• Search and rescue operations in remote areas
• Community networks in areas without traditional infrastructure
• Demonstrations where the government shut down the mobile network
• Back-up communication for emergency services

Realistic expectations

The system requires line of sight between devices, which means that obstacles such as buildings, trees, hills or mountains can prevent successful mesh network connections. Network reliability depends on having multiple Meshtastic nodes in the operating area. The system is limited to text messages and cannot serve as an internet replacement.

Advantages and disadvantages of mesh networks

Mesh networks do not offer a replacement for regular telecommunications, because they have a number of limitations. However, they do form a valuable back-up, especially since everyone actually already has them in their pocket.

Advantages

• Independent: works without internet, power or mobile networks
• Low cost: starter kits are available from 25 euros, without monthly subscription costs
• Simple installation: Plug-and-play solutions, automatic network configuration…
• Long battery life: Many devices run for months without problems on batteries
• Open-source: This gives you complete control over software and configuration
• Scalability: The network becomes stronger as more nodes are added
• Privacy: Local communication without transmission to external servers
• Robustness: The failure of one node has little impact on the entire network

Disadvantages

• Limited functionality: Text messages only, no voice or images
• Low data rate: Maximum 27 kbit/s, which is comparable to old modems
• Range: Requires clear line of sight between nodes for optimal performance
• Network complexity: More nodes can lead to instability
• Weather dependency: Heavy rain or snow can disrupt signal
• User base: Network is only useful if enough people participate
• Technical knowledge: Optimal configuration requires understanding of radio frequencies

Legal aspects and frequency usage

Within Europe, the licence-free 868 MHz band is used for LoRa. This band is divided into five subbands, varying between 863 and 870 MHz. Because this licence-free band may be used by everyone, restrictions have been imposed by the government on the use of this band.

Important regulations

European regulations:

• Maximum transmission power: 25 mW ERP (Effective Radiated Power)
• Duty cycle limit of 10 per cent per hour, calculated every minute on a rolling basis
• No licence required for use within these parameters
• Devices must be CE-marked for commercial use

In the Netherlands and Belgium, the same European standards apply. It is important to remain within these limits to prevent interference with other users and to operate legally.