Survey your site

When installing a wireless network that is going to be used all around your school, it is important to survey the buildings and map out where each wireless access point will be placed.  It will also allow you to find the best positions to place new cabling and to help stretch your budget a little further. 

The best places to start is by obtaining or drawing a plan of your school.  This only needs to be an outline plan that will allow you to get a birds eye view of the school allowing you to break the school into zones.

The next thing that you will need to decide is how many users are likely to be using the wireless system at any one time.  Remember that Wireless is very much like a CB radio system.  Only one machine will be able to talk to the wireless access point at any one time.  So the more machines you have, the slower the wireless will appear.

Look for access points that can support a minimum of 15 wireless devices.  These will typically be aimed at business users and have a much higher price tag.  Generally speaking, allow 10 laptops per standard access point.  So if you have 30 wireless laptops, you may need to have 3 access points.

Once you have the basic details, you can now start to zone your school map.  Access points work best when they are in line of sight.  They can work through walls, but the signal strength will be affected.  If there is a corridor with classrooms either side, the access point may be best possitioned in the corridor, allowing several class rooms to benefit from the wireless connection.

Use your knowledge of the school and draw black lines through your map, breaking the school in to individual zones where wireless access points will be located.  Wireless access points can have quite a range on them when operated in high power mode.  Each Zone will represent a Wireless Access Point.  Remember that you will need to balance the number of access points against the number of machines that are likely to be used in that zone.

The diagram below shows a school diagram there less than 10 machines will be used in a zone at any one time.  The rooms are approximately standard classroom size rooms (8m by 8m) and are separated by a store room.   Access Points will be located in the store rooms.


The reason why you are breaking your school into zones, isn't just because you are working out how far signals from each access point will reach.  You are planning to prevent a serious problem of cross talk.  This is where access points operate on the same radio frequency and cause interferance with its neighbouring access point.

In the UK, the wireless frequency for the 11b protocol is divided into 13 channels.  In theory this means that you can have 13 access points operating and not interfering which each other, however, this is not the case.  The rule of thumb is to leave 3 channels apart.  You could use channels 1, 5, 9 and 13.  Elsewhere on the internet the recommendation is to leave 5 channels apart if you need reliable performance, so use channels 1, 6 and 11.  See NetGear Wireless Channels

Having a small number of available channels will mean that you need to be creative with your wireless access point possitioning.  You don't want wireless access points talking to each other if it can be helped.  If you have a need to install more access points to offer better bandwidth availability on your network, you will need to lower the power output of the access point to compensate, this will reduce the footprint of your wireless zone.

Once you have your Zones mapped out, locate suitable power and network data points.  New data cabling may need to be installed as well as additional power outlets.  If there is no possibility of running a mains power outlet, it is possible to use Power over Ethernet.  Power over Ethernet uses the spare unused wires in a CAT5e cable to supply the required voltage to you access point.  Power is introduced into the CAT5e cable using a special converter module at each end of the cable.

If you require further help with your wireless solution, get a cable contractor to assist you.  They will be able to supply you with details of work required and to assist you in planning your whole school wireless network. 




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