Equipment

For panOULUnetwork to work, some equipment is needed. WLAN connections travel from the user's computer to an access point by an antenna, and from there to panOULU servers, which offer some mandatory services for network users and also route the traffic to Internet. There are three different WLAN radiotypes used in the access points. You may read more about them in the wiki (in Finnish).

Access points

There are four main types of access points in the panOULU network:

Cisco Aironet 1200

Aironet 1200, manufactured by Cisco, is used mainly in University's KampusWLAN and as outdoor coverage in the city centre. The access point complies with the 802.11b standard which works in the frequency range of 2,4 GHz, but also the 5-GHz 802.11a standard in indoor access points.

Cisco Aironet 1100

Aironet 1100 is used by the Oulu Polytechnic's OuluNet. It fulfills the requirements of 802.11g and is capable of transfer speeds up to 54 Mbps.

Linksys WRT54GL

The University KampusWLAN expansion in 2006 will be made by using Linksys WRT54GL access points installed with customized OpenWRT Linux. WRT54GL complies with the 802.11g standard. WRT54GL is also used as panOULU subscription access point.

Cisco Aironet 1240

Aironet 1240 is an updated version of Aironet 1200. By default it fulfills standards 802.11g and 802.11a. City of Oulu will install 120 of these by the end of year 2006 in various locations.

Antennae

For the signal to pass through in different places, antennae are needed. An antenna does not increase the overall power of the signal, but instead directs the power in a suitable way to increase signal strength. panOULU network utilizes two different antenna types, the omnidirectional antenna and the directional patch antenna. There exists also omnidirectional dipole antennae and directional yagi and parabolic dish antennae.

The power of an antenna is often compared to an ideal isotropic antenna. The unit is dBi. For example, a 3-dBi gain for an antenna means, that in horizontal plane the signal strength is twice the amount of the same signal with an isotropic antenna. Because an ideal isotropic antenna does not exist, for practical reasons the antennae are sometimes compared to a dipole antenna. The unit in this case is dBd. A typical dipole antenna has a gain of 2,14 dBi, so 0 dBd = 2,14 dBi.

Omnidirectional antenna

An omnidirectional antenna beefs up the signal from the access point in the horizontal plane, but in the vertical direction the signal is weakened. When compared to an isotropic antenna, a larger area can be covered on the same plane with an omnidirectional antenna. However, for coverage between two floors an omni is not suitable. panOULU network uitlizes mostly omnidirectional antennae with a gain factor of about 5 dBi.

Directional patch antenna

The signal sent by the access point goes out from a patch antenna as a cone with the angle of 30 to 90 degrees. The gain given by the antenna depends on the size of the coverage angle. For example, the gain with a 30-degree coverage angle can be even 12 dBi, but with a 90-degree coverage angle it drops to about 5 dBi. panOULU network utilizes different kinds of patch antennae, but the most common is a 7-dBi gain antenna.

Servers

HP ProLiant DL380 G4

panOULU services are run by five Hewlett-Packard ProLiant DL380 G4 servers. Network users can for example receive an IP address for their computer and send E-mail through these servers. There are also some adminitrative tasks that these five machines run, like log collecting and performing statistical analysis by using the data gathered by the logging server. The operating system in these servers is OpenBSD.