= [ code31.org mxHz.org so-on.be ]


Network Summer  

report network meeting01

bart/patrick/annemie     print
thursday july 12, 2007 – saturday july 14, 2007
okno/so-on, brussels
okno / network meeting01
Date : 12.07.07 13.07.07 14.07.07
Location : okno HQ, koolmijnenkaai 30-34, 4th floor, 1080 BXL

Report status: final
Action required: more workshops
Author: bart/patrick/annemie
Version: 4
Date: 18.07.07
#pages: 9

Cédric Thernon – Réseau Citoyen
Patrick De Kooning - Chemist/Artist
Dimitri Dhuyvetter – Web developer
Olivier Meunier: video/3D Installation artist – Réseau Citoyen
Jan Ritsema – Artist (performing arts)
Olu Vandenbussche – Textile designer
Annemie Maes – artist – okno/so-on
Junior Vandebroeck – artist – okno/isjtar
Bart Vandeput - artist
Pieter Heremans – developer – okno/code31

Free Wireless Mesh Networks (Cédric Thiernon)

What is RC

Reseau Citoyen is a Brussels project for a user-run wireless network via wi-fi. RC has an ideological approach in putting up a free and open network and is run on a voluntary basis.
The volunteers/developers provide the technological expertise and in a collaborative spirit make it available to the inhabitants of Brussels.

RC was initiated in 2000 by Yvan Markoff, Jean-Charles de Longueville (less active now in RC due to a law case) and Marie Anne; and was setup to develop a longterm cooperation/communication project for Africa (called bombolong).
At that time, mesh networking was relatively new.

A Meshnetwork
Mesh networking is a way to route data, voice and instructions between nodes. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from node to node until the destination is reached.
Mesh networks differ from other networks in that the component parts can all connect to each other via multiple hops, and they generally are not mobile. Mesh networks can be seen as one type of ad hoc network.
Mesh networks are self-healing: the network can still operate even when a node breaks down or a connection goes bad. As a result, a very reliable network is formed.
(decentralised: en.wikipedia.org/wiki/Mesh_network)

[ex: Nucleus = 3 nodes
One antenna A communicates with a 2nd B, connected with C. Data flow is from C to B to A
Other antennas/nodes can connect – Mesh principle: when one falls out, info keeps on flowing via the other – another info canal / trajectory is formed...]

Autonomy, techology in own hands allowing all kinds of soft- and hardware experiments; independence.
[Note: unless it’s not the main goal of RC to provide internet, there was a try out providing connection to internet aiming to attract more people to participate in the réseau.]
RC: aspects philosophiques: www.reseaucitoyen.be/wiki/index.php/Aspects_philosophiques
Wireless Free Networks: Why? publication.nodel.org/WirelessFreeNetworksWhyTo

Basics of networks
IP: internet protocol – worldwide (4 billion addresses possible – IPv4)
The entire purpose of IP is to provide unique global computer addressing to ensure that two computers communicating over the Internet can uniquely identify one another.
Internet’s capacity limit is nearly reached, therefore there is a switch going towards Ipv6.
Net mask: only showing part of address
Ports: 80 (port for http internet protocol).

City area network: The IP numbers of wireless city networks are in the range of 10.xx.xx.xx
Réseau Citoyen recently changed nrs; netmask is now only for the last 2 units:
10.93.x.y=brussels; 10.98.x.y=antwerp

How2connect – Where are the nodes
A visualization of the RC network: boum.no-ip.com/gmap/gmap.php

No specific software is required to be able to connect to the RC, given that your local antenna (example okno node) is connected via an ethernetcable to the okno-router. This provides connection to the RC to all computers in the local (okno)network, once a 10.x.x.x address is contacted. Via command line we have to route the local router to the RC-network:
[Welcome to Darwin!
spacevoice:~ annemiemaes$ sudo route add -net
Result = add net gateway]

If you’re not connected by cable to a dedicated node, than you have to install OLSR, a routing protocol software, to be able to connect to the RC network.
The Optimized Link State Routing protocol [OLSR] is a routing protocol that is optimised for mobile ad-hoc networks, sometimes called wireless mesh networks. It is a proactive link-state routing protocol that floods a full topology table to all nodes in the network which then compute optimal forwarding paths locally.

Howto setup a Dedicated Node: hardware
The most common hardware to make a node in the RC network is a Linksys router WRT54GL. The original firmware is replaced by free OpenWRT firmware, or by the Open Freifunk firmware (developed by Berlin’s free wireless network developers).
WRT Router (±70€).
Add a high gain antenna, omni-directional or semi-directional (from 20€ to 80€; or build your own). This is like radio, transformed digitally. The router is put on the roof in a waterproof casing and the antenna is connected antenna.
Connectors: standard is N-connector.
home made antennae: www.reseaucitoyen.be/wiki/index.php/Home_made


Creation of Free Wireless Networks (Patrick De Kooning)

The research and development of an independent network closed for commercial applications, open for the community and their projects.
The internet will only be used for routing between different independent metropolitan networks as necessary. For this purpose long range beam connections over land or by satellite will be investigated.

The network will preferably consist of wireless transceiver nodes which will be self sustainable by the use of solar or wind power generated electricity. For the network hops Linksys WRT54G(L) wireless access points will be used which are able to be reprogrammed with appropriate software to build an adaptive network and are well supported by the open source community.
There will be a detailed concept published for the whole unit consisting of an antenna stand, antenna, wireless access point and power source as a quidance. Placed on the roofs of citybuildings, these will form an adaptive, independent, open and self sustainable network maintained by its creators and create a basis for all kind of technological and artistic projects open to the public.
There is no uplink to the internet for internet connectivity purposes other then routing to adjecent community metro networks. This keeps the network clean and garanties high bandwith for the running applications/ services. Besides the network is not intended to be used as an extension for the world wide web.

-Network topology: the network might be using backbones to connect the hops or the hops form the network when the networks overlap.
-Network protocols: various protocols can be used to build the wireless network itself. OLSR, OSPF, B.A.T.M.A.N. are among the choices. The computers connecting through the network have no need for these routing protocols to be installed.
-different kind of antenna technologies. Depending of the usage of the network and what need to be accompliced a suitable antenna will be used.
-border router for uplinks to adjecent metropolitan networks.
-no usage of any kind of firewall or port blocking on the wireless network. Firewalls can and advisibly should be used when routing out of the wireless network.

concept of setting up a Domain Name Service on the network. This service will run on dedicated and selfsustainable hardware connected to the wireless network.
This will greatly improve network usability and accessibility.
Some think this will centralize the network where as de-centralization is prefered but there is a central record of IP addresses and their users being maintained which on its own is a centralized part of the network.

Possible usages
The network could be used as a platform for hive networks, collaborative and other art projects, local streaming of data, audio and visual content, open source technological projects and sensor data streaming..

Why prefer this approach over the use of the world wide web?
-By using the local wireless metro network it is possible (at the moment) to gain high bandwith both for up and downlink not commonly found in residential broadband connections.
-A community member can contribute to the expansion of the network by placing network hops thereby expanding the range of the metro network and the community interessed to participate and/or usage of the network.
-Free of any kind of censorship or monitoring and datalogging which is common practice linked to the internet these days.
-Free for experiments not limited by ISP/ Government policies.

Self sustainable units
The unit(s) will be made self sustainable by the use of solar or wind power and because they are using wireless technology there is no need for any demand of infrastructure on the location(s) where these units will be positioned.
The location of the units is very important for the choice of the alternative energy source that will be used. In Brussels we should defenitely opt for the wind turbine (or a hybird system with solar) while on other locations solar would be a better choice.
Since we have 2 working units (for now), it would be good to rig one with a wind turbine and the other with a solar system.
In the case of a wind turbine the choice of which type of turbine depends on how steady the wind is on the location. When the winds are directional steady a horizontal turbine needs to be used, when there is a lot of turbulant wind a vertical turbine needs to be used.

Through a series of workshops we will explore the wireless network, its technology, topology, implementation and usability. The series of workshops will be closing with a one week hands-on workshop where the participants will work together building a temporary wireless network, connecting clients to it and sending all sorts of data over the network.

To explain the reach of an antenna, the metaphor of light (flashlight / bulb / laser light) is used.
Frequency: antennas use high frequencies so they need to see one another.
They are pulse modulated.
The more Watts an antenna receives, the further the reach; although with power comes noise, and the quality of the signal is a ratio of power/noise.
Low frequencies is very onmi-directional and requires as lot of power.
Also the physical size counts: the higher the antenna, the more reach (geometrical shape; material and the way you make it).
Weather conditions: cloudy day; rain: omni-directional antennas are no go; than you need a satellite
dish. Band with of electrical tools as cordless phone or microwave can interfere, and also air pollution.An antenna is like an analog instrument.
Band withs are regulated. 2.4Ghz and 5Ghz are free for experiments.
If you are in the very high frequencies (very directed), you are difficult to trace.

Components for an independent unit
Router (12V=>DC)
Dedicated compu (12V 1W) P=V.I
80W solar panel – Kyocera
45A Battery;
Charge controller

In the margin --> Wind mills
Max speed blades=> 1 blade best, but needs a lot of wind to start.
Also systems to concentrate wind

Mini-wind turbines

Low speed wind proof of concept


PureEnergySystems Wiki
wind energy:

ready made rooftop turbines for urban settings

Handson experiments
More pics by dimitri: www.flickr.com/photos/psi36/sets/72157600812681269/
More pics by annemie: www.so-on.be/?id=879

Friday 13.07 and Saturday 14.07 we did some handson experiments. We created a dedicated network with 2 grid antennae, one on the rooftop of okno, the other one on the rooftop of so-on.
Both antennae are semi-directional, approx. 120cm wide and 80cm high and are slightly curved.
The transmitter/receiver is adjustable (slide in/out) in a way that the range can be or very narrow in degrees (and reaches further), or slightly broader and than transmitting in a shorter aerea.
It’s a delicate job (a question of mm) to fix the grid-antenna in the very right angle to the readymade standard (rooftop model).

Both grids are connected to a Linksys WRT54GL router with flashed OpenWRT firmware. The okno-WRT is the master and gives out the IP numbers to the computers connected to this network.
The first day we powered the okno-grid with a solarpanel + battery. The energy of the Velleman-photovoltaic was just enough (270mA) to feed the router, but we had to deconstruct the setup as we did not include a regulator for the battery (we didn’t had one) and thus the setup became to risky to blowup the Linksys (when battery runs out or overcharges).

So finally we connected the 2 Linksys routers to the regular power network. This means that an ugly powercord runs down from the rooftop as far as to be plugged in the nearest power-point inside. The same thing for connecting to the local network via the inside router: an ethernetcable has to be run down all the way.
An urgent next step is: to power the antennae with alternative outside sources and make them self-sustainable and idependent from the regular power-network. A second step is to make them wireless accessible.
Only then we will be able to speak about indepentent and mobile network modules!

The IP address of the okno-grid is
The IP address of the so-on grid is
When you connect to this network with your computer in DHCP-mode, the okno-grid-router will give you a dynamic IP between 50 and 100.
You can also connect with a fixed IP (for ex. If you work with a dedicated computer or want to send out a fixed url for streaming). Than you have to choose an IP between

On the local webserver of the computer an index webpage can be setup with all info about what’s going on.

Follow Up: What to do next?
Workshops for september/december and january/april

Okno Grid Antenna: power supply by sustainable energysource (solarpannel, windmill)
So-on Grid Antenna: idem
Put a regulator for the battery to stop charging when full.
Is it possible to make them wireless accessible? (no ethernetcables animore!)

Antenna Workshop:
Make your own antenna dedicated to the needs of a specific project

Windmill Workshop:
Make your own windmill dedicated to the needs of your project

Sensor Workshop:
Compose your own sensors dedicated to your project

Wireless & Low Power Workshop:
Compose your own dedicated unit and power it by wind or sun:
- Hardware/router
- Antenna
- Sensors + controllers (ex. Hives or homemade)
- Server (web- and/or streaming-server)




okno --- koolmijnenkaai 30/34 --- 1080 brussels --- belgium --- steklo♥okno.be --- tel +32 2 410 9940