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AREDN Basics

An introduction by Timm Schunck, DL4FLY

Preface

In a typical emergency radio scenario, the sender delivers a message to a radio amateur who records it in a radiogram. The message is then transmitted over VHF/UHF or shortwave via voice radio. In some cases, the handwritten form is transcribed a second time and forwarded via email (pactor/packet). The form then reaches the recipient. In the worst case, the message sent by email has to be transcribed again so that it can be handed over.

This procedure does not meet the expectations of government users. They expect continuous use of the media they are accustomed to, namely email, telephone and similar web-based tools, depending on their function in the organization.

But what is AREDN? (pronounced Arden)

AREDN is a meshed radio network that operates in the amateur radio bands. It is a high-speed network with data rates up to 54 Mbps, designed to provide a TCP/IP medium when other network infrastructure is already down. Although technically possible, it is not intended as an alternative to conventional Internet access.

AREDN was written by the AREDN development team as an evolution of the award-winning BBHN (Broadband Hamnet) firmware for LINUX-based WIFI and WISP (Wireless Internet Service Provider) devices. AREDN was recognized for this by the ARRL in early August 2018. AREDN replaces the manufacturer firmware of the devices with the following main components:

1. OpenWRT, an open source wireless routing framework on which custom developments can be built.

2. OLSR (Optimized Link State Routing Protocol), an IP routing protocol optimized for dynamic ad-hoc networks

3. web-based interface for configuration

4. automatic device-specific TCP/IP configuration based on the MAC address of the device.

The primary goal of the project is to enable radio amateurs to become a part of the network, install firmware on the devices and use them.

The second goal of the project is to develop standards and services for emergency radio use of this technology. AREDN thus enables a high data throughput combined with a simple setup of a standard TCP/IP structure. Therefore AREDN behaves like a local wired home network. Therefore common services like telephony, e-mail, web server, cameras, chat, etc. are easy to implement.

Difference to stationary Hamnet

Classic Hamnet: Routes are planned, each link on a different frequency, central assignment of IP addresses is required. When installing, care must be taken as to which terminal is to operate as an access point and which as a station.

With ARDEN, all nodes operate on the same frequency. Only in the case of several link routers at one location it may be necessary to set individual point-to-point links to a different frequency.

Advantage: Everyone sees everyone.

Furthermore, the network is designed as an ad-hoc network, which means that anyone can connect to anyone. A sophisticated logic in the OLSR finds connections between different nodes and evaluates the quality of the connection (“cost of link”). If packets are transmitted, the “cheapest” route is selected. If a part of the route fails, an alternative is routed.

For use in emergency radio, this means: Fast setup on a standard frequency, set and forget. Plug in, set up, the rest is automatic. If services such as VoIP telephony or a web server/email server are operated at a node, these services are automatically announced in the network and are immediately accessible network-wide. Ring structures and cross-connections can also be easily implemented in this way.

This would be very difficult to implement using conventional technology. For example, the secondary radiation of one node is sufficient to connect a second one, even 50m away, although both mirrors point away from each other to other remote stations.

Source: https://www.darc.de/der-club/referate/notfunk/aredn-amateur-radio-emergency-data-network/

Further information:

• https://www.arednmesh.org/
• https://www.hb9fts.ch/aredn/

Translated with www.DeepL.com/Translator (free version)

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AREDN HamWebinar Series 2023 by HB9BLA

Presentation: Einführung In AREDN

Recordings of the AREDN HamWebinar series 2023 by Andreas Spiess HB9BLA:

 

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Introductory video by HB9BLA, USKA “New Technologies” board member