The big players in enterprise Wi-Fi are competing to provide continuous Wi-Fi coverage in large buildings, and wireless access for thousands of staff. But there's another side to the wireless industry, where innovation is, if anything more in evidence.

Small businesses can have greater need of Wi-Fi, as they move rapidly between offices, and can need to re-arrange those offices rapidly due to change or expansion. They don't own their premises and may find it difficult to install wires, and they don't have dedicated IT staff who know how to do this. A system that simply fills the building with Wi-Fi and gives access anywhere should be very attractive.

The smallest office can have a single access point that can give all the staff access wherever they are (perhaps with a few Ethernet ports for stationary users to take the load of the Wi-Fi). But most organisations will need multiple access points.

And that is the opportunity that several companies are moving to meet.

Wi-Fi systems that have a few access points, are easy to install and maintain, for the smaller office. They all have to have security features, including the ubiquitous WPA encryption, but probably don't need the full-on IPS/IDS features that large enterprises like.

Apart from that, the field is open for vendors to meet the challenge any way they choose. And they certainly have done this.

Netgear, the doyen of small business networking is in there, with the WFS709TP system which - on our review - turned out to be a reduced and simplified version of Aruba's more heavy-duty Wi-Fi switch system.

D-Link is there too, as you'd expect, with the DWS-3024 wireless switch, intended to deliver a subset of the function of Trapeze or Aruba for somewhat less - and we guess is probably based on one of the other vendors' technology.

Symbol (now part of Motorola) has the WS2000 branch office switch that can manage six access points attached to its Ethernet ports, four of which have power over Ethernet. It's a mature product, launched in 2004, and Symbol's competitors tell us that these aren't often sold into "carpeted" offices outside Symbol's normal retail-and-warhouse markets - but the company is certainly selling plenty. This was apparently the biggest selling wireless switch (in terms of units, not ports) in the last quarter.

Trapeze has had its branch office system, the MXR2, pretty much as long as Symbol's, but it's really intended to be a satellite to a central Trapeze system, and Trapeze is focussed much more on larger-scale installations.

Ruckus Wireless is now selling its ZoneFlex system to larger companies than its initial SME focus, but it has a feel that suits it well to the smaller company. The system is deliberately built with cost in mind - Ruckus' six-antenna system extends the range and penetration of Wi-Fi signals so fewer access points are needed. It also has an 802.11n product on the way, which will use the 2.4GHz band only, and staying out of the 5GHz band till silicon gets cheaper.

Another old friend is Extricom, whose "blanket" Wi-Fi system we have seen in in smaller installations.

Each access point is set to the same channel in the 2.4GHz band, so there is no roaming, and no need for a site survey, as access points won't interfere with each other. The central switch handles the switchover of clients form one access point to another when users are on the move.

There are also still plenty of alternative vendors old and new. Xirrus has been around for a few years, with the idea of building the access points inside the switch, creating a large disk that sends Wi-Fi signals out in sectorised beams.

It has passionate supporters, who point to its ability to limit signal leakage to the outside world, and the reduction in cabling for APs. It has also announced plans for 802.11n/

A new company, due to launch in Europe soon, takes a radically different approach. Aerohive has no centralised switch, but each access point takes part in a self-organising system, a little like a mesh, but linked over Ethernet if available.

There's a certain buzz around Aerohive, which has received venture funding and was founded by a group of former Netscreen staff. The company claims that it can scale upwards - particularly with the addition of management software, but till we've tried it, we are going to wonder if it suffers from the problem of escalating communications among the APs causing overheads.

There are still traces of older approaches - Bluesocket made its name early in the Wi-Fi market with a "gateway" that connects wireless APs to the network through their own firewall. It was pitching at small businesses when we last met it - but has recently bought a VoIP player and looks like repositioning.

With all this going on, wireless for SMEs looks like remaining a tricky issue to negotiate, with plenty of choices. It's in the nature of the sector that most often the choice will probably be made by the third party integrator. What they're all looking for - far more than cheapness - is ease of integration.

The WLAN has to be put in with no trouble and little training, or the cost of the equipment rapidly gets swamped.