Basic information you need to know about Wireless Networking.

More and more schools are seeing wireless networking as the future for making better use of ICT in the classroom.  With the competitive pricing of laptops and wireless kit there is a big market for this type of technology.

However, as with any major project, planning is vital.  This article aims to point you in the right direction so that you can make informed decisions about your network and use of technology.

Before you start buying your kit you need to consider what you are trying to achieve with wireless.  Are you looking to create a mobile computer suite?  Or perhaps providing students and staff with the facilities for being able to work anywhere in the school.

Wireless everywhere

If you are looking at a whole school based project, you are best to get the professionals in who will be able to give you a site survey and will quite happily manage the project for you.  However there are things that you can do before you reach this stage. 

  • Get a map of the school (with each classroom detailed on it)
  • Mark on the map where existing network points are located
  • Make a note of thick brick walls
  • Make a note of metal framed windows or pillars

Now that you have some basic information, you will be able to plan the best locations for access points.  If your budget is quite small, perhaps an access point could be shared between classrooms.  As a rule a reasonable signal range of about 15 to 20 meters can be obtained from modern access points.  Some of the better access point models will be able to penetrate thin walls without a problem.  Place an access point near an existing data point and powersource where possible (this aids self install).

On UK access points there are 11 channels available for use.  This is actually quite important as each access point that is in the same location should be operating on its own channel, otherwise there will be performance and connection issues.  As you have a plan of where the access points are going to be, assign possible channel numbers to each room.  If your rooms are in a straight line, the example below will give you some idea of how to setout your channel plan.

Room 1

Room 2

Room 3

Room4

Channel 11

Channel 9

Channel 7

Channel 5

If you have more rooms, then you will be able to reuse channels. for example.

Room 1

Room 2

Room 3

Room 4

Room 5

Room 6

Room 7

Channel 11

Channel 9

Channel 7

Channel 5

Channel 3

Channel 1

Channel 11

If you have classrooms in a block, you will need to be a little more creative with your access point channel allocation.  For example

Room 1

Room 3

Room 5

Room7

Channel 11

Channel 9

Channel 7

Channel 5

Room 2

Room 4

Room 6

Room 8

Channel 5

Channel 1

Channel 3

Channel 11

Which ever model you choose is only part of the jigsaw.  If the access points are close together there would still be cross talk between the access points.  This can be compensated by the controls on the access point by lowering the signal strength.  So far we have only covered the oldest of the 3 wireless protocols (11b), however the same principles apply to the other 2 protocols (11a and 11g).

If you need to cover a fairly large area and only one access point is appropriate, the range of the wireless signal can be boosted by using different types or arial.  There are 2 types of arial, Directional and Omni-directional.  The important factor with these arials is the dB gain that the arial uses.  The higher the dB the better the signal strength.  Remember that your laptop or PDA may not be able to connect even if you have a higher gain on your access point.

When having wireless access points fitted it is possible to use a product called power over ethernet.  What this means is that you would only need to worry about getting a network point close to where you need the access point.  The power would then be supplied over the data cable to the access point using a special module on either end of the connection.  The power supply for the access point could be upto 100metres away from the access point.  Saving potentially high costs of getting a new mains supply fitted.

Totally Mobile

Another option available is to use mobile acces points.  Several smaller schools use this method successfully.  The access point is attached to a metal trolley that stores the laptops.  Typically the access point will be plugged into the network point in the classroom when it is needed.  This saves money on the installation of dedicated wireless access points.  If an teacher need to use their laptop in the classroom when the wireless system is being used elsewhere, they are able to use the hardwired network point.

There are obvious cost savings with this method, not to mention not having to worry about setting different access point channels.

Wireless Security

WEP short for Wired Equivalent Privacy is a security protocol for wireless local area networks defined in the 802.11b standard. WEP is designed to provide the same level of security as that of a wired LAN. LANs are inherently more secure than WLANs because LANs are somewhat protected by the physicalities of their structure, having some or all part of the network inside a building that can be protected from unauthorized access. WLANs, which are over radio waves, do not have the same physical structure and therefore are more vulnerable to tampering.

WEP uses data encryption keys to scramble the data so that it can’t be intercepted.  This also provides a method of securing your access points from casual users.  In order to access an access point with WEP enabled you will require a key, this is usually provided by  the network administrator and looks something like 45 AB 3A B6 CA CC.  The length of the code will be dependant on your access point hardware.  It is important to note that different manufactures implement different forms of encryption keys, so you should make sure that your equipment conforms to WiFi standards.

Linking 2 buildings together

Wireless can be used as a cheap alternative to an outside fibre optic cable.  Most access points will operate in Bridged mode.  This means that the access point will only talk to the other access points in the bridge, connecting 2 different physical networks together.  In order to do this you will need line of sight between the 2 buildings and preferably 2 identical access points.  Specialist arials may also be required if the distance is greater than 20 metres and the location is outside.

Places to visit

DLink Equipment Manufacture http://www.dlink.co.uk
Netgear Equipment Manufacture http://www.netgear.com
Dfee Wireless Guidelines
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