WiFi technology (IEEE802.11) can be broadly categorised to IEEE802.11 a/b/g/n/ac. Each is an improvement in transmission speed and/or signal range from the previous, although these days only ‘G’ and ‘N’ are used.
The standard G versions of networking devices have an optimal transmission speed of 54 Mbps with an indoor range of approximately 40 m whereas the N versions have a theoretical maximum speed of 300 Mbps (practical of approximately 150 Mbps and above) with an indoor range in the region of 70 m.
In addition to this, N variations offer the choice of two frequency ranges; 2.4 GHz or 5 GHz. The higher frequency has no impact on the range but offers a potentially less polluted frequency to help reduce crosstalk noise.
Both the G and the N devices utilise the same channel capabilities but these vary regionally. In Europe (including UK) a channel system of 1-13 is used whereas in the US the system uses 1-11. Both use the same frequency ranges resulting in an approximate frequency void of 16.5 MHz at the end of the 2.4 GHz range.
Japan utilise a different system still, expanding the 2.4 GHz range beyond the acceptable ISM guidelines by 10.5 MHz to allow for an additional 14th channel with 11 MHz of non-interference from other channels (see Figure below) , , .
Image. 22MHz channel allocations for WiFi 2.4GHz frequencies, with curvatures implying affinities for intra-channel frequency selection.
The figure above shows the affinities for the frequency selection within each 22 MHz channel and the overlap between channel frequencies. The same would be seen for 40 MHz channels with the obvious exception that there would be twice the amount of overlap between channels, leaving fewer isolated channels. The solid lines show the 3 channels in the US 11 channel system that do not encroach on each other’s range at all. Each WiFi access point will secure its own channel and use that channel for all communications. Multiple channels will not be utilised by one access point other than during overlap.
WiFi communication protocols are Internet Protocol (IP) based where the destination address is in packet headers allowing large amounts of data to be transmitted through a network of nodes at high speed. This means that on any WiFi network a central control node (network coordinator) will allocate all IP’s in the network on discovery allowing for any packets to be addressed and routed to a connected device .
This article was created by --BRE. It was taken from The future of electricity in domestic buildings, a review, by Andrew Williams, published in November 2014.
NB The term 'WiFi' was coined by the Wi-Fi Alliance as shorthand for wireless local area network (WLAN) products based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards. It did not specifically 'stand for' anything. It has popularly been adopted to mean Wireless Fidelity but this is not correct.
 Related articles on Designing Buildings Wiki
- Glossary of electrical terms.
- ICT and Automation (ICTA) Scoping Study Report.
- In-building wireless.
- Information and communications technology.
- Internet of things.
- Local area network.
- Smart buildings.
- Smart cities.
- Smart technology.
- The future of electricity in domestic buildings.
 External references
-  E. G. Villegas, E. López-Aguilera, R. Vidal and J. Paradells. Effect of adjacent-channel interference in IEEE 802.11 WLANs. Cognitive Radio Oriented Wireless Networks and Communications, Orlando, 2007.
-  Butler J. Wireless Networking in the Developing World, Copenhagen: Creative Commons, 2013.
-  Institute of Electrical and Electronics Engineering, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE Standards, 2012.
Featured articles and news
UK-GBC green paper proposes more powers for cities on new-build housing.
The Pompidou Centre – not a monument but an event.
The Chartered Institute of Building restructures and launches 29 new local hubs.
Designing Buildings Wiki talks to the founder of the world's first indoor biophilic gym, now open in London.
£1.3bn Swansea Bay project to be backed as a 'pathfinder' for other tidal lagoon projects.
Designs released for a proposed Las Vegas stadium to entice the Oakland Raiders.
Have a look at these award-winning concept designs for a thermal bath in Latvia.
Flagship project no longer "a going concern" according to the Garden Bridge Trust as funding slows.
How the work of 20th century urbanist Jane Jacobs continues to resonate in light of the government's garden village plans.
New landmark for the Ecuadorean capital of Quito utilises a sinuous facade mold system.
Have a look at this glass piano and violin building in China.