Interference causes numerous network issues and is a significant blocker to a fast, reliable Wi-Fi signal. Varying degrees of interference can occur including one or all of the below:
Every device will poll an Access Point on the same Wi-Fi channel, sometimes referred to as congestion. More devices equate to more polling, this congestion can result in a delayed network. This only becomes problematic with large numbers of clients.
Adjacent Channel Interference
On 2.4GHz there are only 3 usable channels. Access point signals across these channels can overlap each other, which means channels are re-used, reducing the signal strength and at worse cancelling signals causing the dropout of networks.
Other non 802.11 devices such as microwave ovens, lighting systems, security and CCTV cameras, can interfere with the Wi-Fi signal, reducing quality and performance of the network.
Prior to the deployment of a Wi-Fi network, it is highly advisable to conduct a Wi-Fi Site Survey to highlight issues and identify ideal deployment and optimisation of the network. In a Wi-Fi site survey, the signal to noise ratio (SNR) will be recorded to identify the difference between the signal strength and any interference, and is a direct indicator of a networks’ performance. An analysis of the spectrum can also be conducted using a spectrum analyser to assess the occupied space on an already deployed network.
REDUCE CO-CHANNEL INTERFERENCE
The key to reducing co-channel interference is to review strategies that will improve the data rate (the speed of communication from client device to the Access Points).
Wi-Fi protocols set the limit to the capability of your Wi-Fi. The most advanced standard available in Australia is the 802.11ac which enables 24 channels in the 5Ghz frequency and an extremely high data rate of 1.3Gps.
Review your hardware, does it need upgrading? Data rate will be capped at the fasted transmission of either the client or the Access Point. For example; If the client device supports up to 300Mbps but the Access Point only supports up to 54Mbps. The Access point will limit the speed of transmission. By upgrading older equipment to support more advance Wi-Fi protocols, you can open your network to both frequencies, increase channel choice and open more bandwidth.
With more modern protocols, you can also include MIMO. MIMO (multiple input, multiple output) is an antenna technology for Wi-Fi in which multiple antennas are used at both the source and destination. This enables many devices and clients to communicate to each other simultaneously. The antennas are used to optimise data rates.
REDUCE ADJACENT-CHANNEL INTERFERENCE
Companies should be making more use of the 5GHz band to reduce adjacent channel interference. By identifying your networks signal strength, frequency, bandwidth and channel choices at specific locations, you will be able to choose the optimum set up for increased Wi-Fi performance.
Also, is your Wi-Fi network located correctly? You need to ensure the location of your WLAN and Access Points are optimally placed to ensure ideal coverage and to reduce signal overlap. Overlapping signals reduce the quality of your network and can cause dropouts of data. Simply turning up your signal strength could inherently make the problem worse. Strategising the optimum channel selection based on the location of each Access Point is crucial in reducing adjacent interference. It is good practice to ensure adjacent channels on adjacent access points differ.
Neighbouring networks also cause adjacent interference, selecting a different frequency, Wi-Fi protocol, or channel to your neighbours can prevent their network interfering with your network performance.
REDUCE NON-WIFI INTERFERENCE
- Thick plaster walls that contain chicken wire for support
- Concrete brick walls
- Metal wiring/supports in walls
- Large metal objects like file cabinets
- Cordless phones
- Microwave oven (Microwaves block Wi-Fi signals when on)
- Baby monitors
- Wireless security systems
- Wireless sound systems
With Wi-Fi there are always trade-offs between location, Wi-Fi protocol capabilities, frequency choice, bandwidth availability and channel selection and that is why a Wi-Fi site survey is highly recommended to utilize the available spectrum in the most optimum way at the least cost of ownership.
NetWireless is a multi-disciplinary IT Network and management company specializing in Wi-Fi design, deployment, security and managed services. Speak to our technical consultants today (CALL 1300 324 844) to ensure your Wi-Fi infrastructure meets your needs.