WiFi: A Quick Introduction
Before we get ahead of ourselves let’s take a moment to look at what WiFi is.
At a fundamental level, WiFi is just a means of transmitting data through the air rather than through a cable. It uses something most of us consider a bit of a mystery – radio waves.
Ordinary cabled networks work by sending electrical pulses down a physical wire. WiFi involves a small electronic chip connected to an antenna, which is used to convert these same electrical pulses into a radio wave.
The unit in charge of communication in a WiFi network is called an Access Point. All devices that talk back to the Access Point are called Stations.
A radio wave is a type of electromagnetic wave, not much different to a wave of light. In fact, we can technically transmit data wirelessly by turning a lightbulb on and off in a sequence. But light doesn’t travel very far, so we use a lower frequency wave that can bounce off walls and penetrate through thin materials.
There are two frequency bands that the world has chosen for WiFi – 2.4 GHz and 5 GHz. Being the lower of the two, 2.4 GHz travels further and is more reliable for larger outdoor networks. 5 GHz can’t travel as far but has a lot more capacity, which means it can handle much more data and operate in busier environments.
Because we have to communicate potentially between rooms or around objects, WiFi needs to be able to adjust the speed it transmits. Essentially this means talking slower in noisy environments to make sure all the information goes through.
It’s a consequence of this adjustment that we experience big changes in how well our WiFi works. Some of the biggest culprits to poor WiFi performance are listed below:
Physical objects in the way
WiFi works best when there is a clear path between your device and the WiFi Access Point. The clearer the path, the cleaner the signal, and hence more information that can be packed into each millisecond of transmission.
Powertec uses advanced radio modelling software to design WiFi networks that not only account for obstructions but leverage reflective surfaces to eliminate dead spots and provide high speed reliable wireless communication.
Like traffic on a highway, the speed of your WiFi connection depends on the number of users transmitting their data. When another device is sending or receiving data from the Access Point, your device must wait its turn.
This means an effective WiFi network design must account for capacity by coordinating a number of Access Points together, much the same as building more highways to meet the extra traffic. Powertec can help estimate demand and design a WiFi network which meets a guaranteed performance objective.
Other WiFi networks
Radio spectrum is an incredibly valuable resource. Because everyone in the country must share only two bands (2.4 GHz and 5 GHz), other WiFi networks play a big part in performance. Within your network, the Access Point can manage traffic to ensure users wait their turn. In the presence of overlapping WiFi networks, Access Points and users clash as they compete – transmitting louder and longer to make sure their own information gets through, causing even more interference to others.
Powertec’s WiFi engineers recognise the complexity of operating in shared spectrum, using spectrum analysis and RF planning tools to carefully develop networks which isolate and compensate for hostile interference.
To make sure people share the public spectrum, the government regulates WiFi spectrum and imposes strict limits on maximum power levels. The consequence is that WiFi can ordinarily only travel a short distance.
Communication between a WiFi Access Point and a device such as a phone or laptop has a hard-limit of about 120 metres. To get around this limitation, a large number of WiFi Access Points are used to provide coverage throughout a large building, university campus, or large outdoor area.
Instinctively we might ask, why can’t we use a larger antenna? It’s because a larger antenna would breach the effective radiated power (EIRP) limit. For specialised equipment, such as machine control and IoT sensors, Powertec can develop systems which use bidirectional external antenna, allowing very large WiFi networks to be constructed. In certain environments such as tunnels and underground mining, Powertec also use a technique known as waveguiding to extend transmission further than their ordinary distances.