Anyone looking into installing a wireless system will eventually ask the question "Which protocol do I go for?"  The answer to this question can be worked out by assessing the equipment that you already have in the school and the type of equipment you will be getting.  You will also need to know about your expected data throughput that you might want to use over a wireless connection.

All networking data systems are classed by the number that was given to committees made up from technical advisory groups, corporations, academics, government and military groups that are formed by the Institute of Electrical and Electronics Engineers (IEEE).

Wireless networking is discussed in the 802.11 committee and has been under discussion since before the early 1990's.  In 1992 early specifications included Infrared, Microwave and Spread Spectrum Transmission.  The top speed was a fast 15Mbps with a range of up to 100feet.

Of course technology has moved on since the early 1990's and the committees have formalised the standards that we currently use.

802.11a
Was the first commercially viable solution for the type of wireless networking that is used in modern computer use.  It operates in the 5Ghz spectrum range.  The standard has a top speed of 54Mbps with a range or about 60 feet.  The standard is useful for data hungry users who require almost LAN data transfer speeds.  The typical uses are broadcast video, video conferencing or manipulating large files.  This standard typically required a licence from the government to use, although I believe that this is no longer the case.

802.11b
This standard uses a frequency that has been allocated for public use.  It operates in the 2.445 to 2.475Ghz range.  The 11b standard offers a top data transfer rate of 11Mbps and has a maximum range of 300 feet.  As there was no licence required to use this radio band, it quickly became adopted in many businesses and became the cheaper alternative.  11b can be used for most normal network activity from logging on to saving files and surfing the internet.

802.11g
This standard uses the same frequency range of 11b standard but offers a larger data transfer rate.  The standard allows for a 22Mbps standard rate of transfer but can reach speeds of 108Mbps depending upon the brand of hardware that you use.  The good thing with 11g is that it is fully compatible with the 11b standard that will allow networks to drop back to a more compatible speed. [Off-site Article:802.11g The next best thing or next last thing]

SuperG
This is an adaptation of the 11g protocol that allows speeds of 108Mbps, when combined with MIMO (multi-in and multi-out) the range and speed of a connection will remain consistent.  Netgear offer a Wireless Access point with the MIMO SuperG technology. [Off-site Article:RangeMax Wireless Access Point]

Choosing a standard
There are advantages and disadvantages of choosing each protocol, however for a small price premium you can purchase Wireless devices that operate in all 3 standards enabling a fall back protocol to 11b if 11a or 11g are unavailable.

One of the biggest problems with wireless is the unpredictable nature of the signal.  It is almost impossible to guarantee that a connection will be made at a distance from an access point.  It is also impossible to predict which access point a wireless client will connect to in a multi-access point area.

From experience I have visited schools where they have installed wireless networks themselves and configured WEP etc, but failed to make a survey of signal strength and possible sources of interference.  On of the important factors when installing a 11b/g network is to take into account any DECT handsets, wireless surveillance cameras and the possible interference from domestic access points.  Channel frequency numbers should be chosen wisely to minimise cross-talk that will impact on the performance of a wireless network.  If a wireless signal is unreliable try a different channel number.  If possible take a survey of your site so you know roughly what to expect.

Thankfully wireless experts are now getting hot on this area and are designing software and hardware that will help to distribute the network load across multiple access points.

If you are on a budget and can only afford to buy a single protocol, I would suggest using the 11b/g protocol it offers the most compatible method of networking and will fall back to the slower protocol should interference occur. [Off site Article: The Big Question: 802.11b or 802.11g]