What is Wi-fi?

Wi-fi is a wireless technology that operates on the 2.4Ghz and 5Ghz band. It allows electronic devices to send and transmit data to each other, over a local area network (LAN) or over the Internet. Wi-fi was built on the 802.11 standard and there are various versions of this, i.e 802.11a/b/g/n with each one having specific characteristics. A Wi-fi alliance was formed to promote Wi-fi as a technology. Many devices use Wi-fi such as Smart Phones, Video Games Consoles and some digital cameras. Wi-fi devices connect to a LAN or the internet using an Access point. Typical ranges of an access point vary from 20 meteres indoors to apporximately 50 metres outdoors depending on the location and infrastructure. Wi-fi networks are set up in two ways  – Infrastructure and Ad-hoc mode.

Infrastructure mode:

In infrastructure mode a wireless network is joined to a wired Ethernet network while still supporting connections to wireless clients. At least one access point is required. The access point and all the wireless clients on the LAN are configured to use the same network name, i.e SSID. The access point is connected to the wired network via a cable. This enables the wireless clients access to the Internet or printers etc. Additional access points can be added to the network to increase its reach and support more wireless clients.

The advantages of this type of network include scalability and centralised security. The disadvantage is the additional cost of buying more access point hardware.

Wi-fi Infrastructure mode

Wi-fi infrastructure mode set-up

Ad-hoc Mode

In Ad Hoc mode wireless devices connect directly to each other. They find another device within range and communicate with each other in a peer to peer manner. A centralised access point or router is not required in the network.

To set up an ad-hoc wireless network, each wireless adapter must be configured for ad-hoc mode rather than infrastructure mode. All wireless adapters in the network must use the same channel and SSID.

Ad-hoc networks work well where there are small groups of devices close together and connected to each other. Performance suffers as the number of devices grows and large ad-hoc networks are more difficult to manage. Ad-hoc networks cannot connect to wired local area network or to the Internet without installing a special-purpose gateway.

Ad hoc mode is used when building a small all wireless network and has the advantage of not being as expensive as infrastructure mode. Ad hoc networks are used as a temporary setup if infrastructure mode hardware (access points or routers) stop functioning.

Wi-fi Adhoc network

A typical Wi-fi ad-hoc network

Wi-fi in industry:

Wi-fi networks are gaining popularity in industrial applications. The standard is easily understood and the cost of modules has reduced significantly. Many embedded modules are now available with real-time operating systems (RTOS) and a built in serial port interface that allows a wireless connection to many devices, e.g an E.C.G monitor while needing only a basic understanding of wireless communications. Security is a issue however and we offer an additional security layer on top of whats already available. We supply embedded and boxed Wi-fi hardware manufactured by Digi International. This is high quality, long life hardware that comes with excellent functionality and customisation options. Please contact us for more details.