The technique of Wireless Leiden

Dit handboek maakt u wegwijs in de techniek van het Wireless Leiden netwerk

Around the city

About Wireless Leiden

Mission, vision and strategy

Established in 2002, the Wireless Leiden Foundation has created an open, inexpensive, fast wireless network for the Leiden region. This is a local network, that integrates seamlessly with the Internet, but can also be used for free, local communication in the Leiden region. Wireless Leiden is a non-profit organization, operating entirely by professional volunteers and aims at creating and maintaining the wireless infrastructure. All the software, technological and organisational knowledge is freely available to others under an 'open source' license from Wireless Leiden Foundation.

We feel that being a non-profit organization is essential for the success of the project and for minimizing the costs. We do not build isolated “hot spots”, on the contrary, we erect nodes that are interconnected wirelessly. . These nodes are the access points for the users in the area around the node. Also mobile users and visitors or tourists can use the network, no registration is required. Not every node needs a direct connection to the Internet, a limited number of gateways connecting the Wireless Leiden network via a router/firewall to the Internet is sufficient.

At present several gateways to Internet are operational. Also individual users can share their own internet connection to neighbours and friends, as long as they are able to connect to the network. We want the local network to be easily and freely available for making connections, for information sharing and to experiment with new applications.

The project is founded on cooperation and enthusiasm of volunteers, businesses and organisations. The costst are minimized by using inexpensive hardware, open standards, open source software and – most important – volunteers, in a cooperative, planned, non-profit approach.

Organization of Volunteers

A group of professional volunteers forms the core of Wireless Leiden. They bring knowledge and experience in a wide ares of disciplines, such as software development, radio technology, network planning, monitoring and public relations.

We have chosen to use a foundation as our legal entity rather than an association with members, in order to speed up decision processes and minimize formalities. As we have no commercial interests we can easily cooperate with both commercial and non-commercial partners, like the Hogeschool Leiden (College) and Leiden University (Leiden Institute of Applied Computing Science, LIACS).

We stimulate and promote commercial activities of others using the network and as spin-offs. We publish our knowledge and experience at the websites:, and
Following the “open source” philosophy we like others to use our knowhow and share their experience with us. Many municipalities in the Leiden area have made connections to our network.

Coöperative structure, social network

The cost of a WiFi network can be minimal, amongst others because no license is required. Of course the use of a 'free' frequency also has its drawback: one man's signal is another man's noise. A coordinated approach has therefore important advantages. Also a single integrated local network is much easier to manage and more useful than separate, individual local connections. For some connections there is simply no alternative because of obstructed view lines.

We intend to make it more attractive for everybody to be part of the network rather than to build their own solution. Also because of the cooperative non-commercial approach we have free access to strategic locations that would otherwise not be available, like churches, and monuments. Almost all the costs are in the equipment for the nodes.

A basic network structure

Our initial approach was to set up a basic infrastructure providing coverage of the entire city with a limited number of strategic locations forming a grid interspaced at about 800 meters. We attempted to postion our first nodes close to these 'ideal' locations. Soon we found out, however, that an approach based on the interest and cooperation of third parties was much more successful. Since then the network has been growing 'organically', grasping opportunities where they occurred.

Some examples of the use of the network:

  • internet with smart phones
  • companies and households temporarily without internet connection because of service interruption or move to a new location
  • video (webcams) e.g. new building projects, outdoor sport events.
  • Streaming video to internet when local upload capacity is insufficient
  • internet connection for outdoor (sport-) events
  • internet connection in 'remote' locations such as the lakes area
    elderly homes (internet connection in private rooms)
  • home users (low budget or no wired connection available students, visiting scholars etc.)

Research and Development

The Wireless Leiden wifi network offers a unique opportunity to develop and test new technology and new applications. We cooperate with several institutes like Hogeschool Leiden (College), the “Centre for Technology and Innovation Management’ (CeTIM), the‘Institute for Societal Innovation’, (IMI), the ‘Leiden Institute of Advanced Computer Science’ (LIACS).

Wireless Leiden has been registered as an experimental infrastructure in het EU Infinity Project (