Signal Attenuations and Quality of Experience

Various environmental factors can degrade WiFi performance. The factors that affect WiFi signal attenuation include absorption, reflection, diffraction and multipath:

  • Absorption is a physical phenomenon in which radio waves are blocked by some material. Highly absorbent materials for WiFi signals include concrete and brick. If a building contains a large amount of these materials, it is very important to take into account the effects of signal absorption.

  • Diffraction is a phenomenon in which a signal passes through a material and becomes weaker or more muddle. A wide variety of materials can cause diffraction.

  • Reflection is when a signal bounces off a surface. Reflective materials include glass, whiteboards, and plastic.

  • Multipath can cause problems with WiFi performance. This happens when the client device is being bombarded with various signals, including reflected and diffracted signals.

The most spread signal strength indicator for WiFi is RSSI (Received Signal Strength Indicator), measured in dBms. RSSI depends on the distance between AP (Access Point - router) and STA (Station - client) and radio propagation issues.

 
 

RSSI directly influences the bit rate: with increasing the RSSI, the bit rate also grows and therefore, user loyalty becomes higher (and vice versa). The signal strength also relates to coverage.

 
 

If there are too many devices with low RSSI, advanced planning of router placement is needed!

In our Support Portal, RSSI values are recalculated from dBm to percentages to represent the relation with connection quality:

 
 

TR-069 or TR-369 protocols can be used to obtain the information required for analysis (Device.WiFi.AccessPoint.{i}.AssociatedDevice.{i} field). The list of necessary parameters is shown in the table below.

 
 

Note that the SignalStrength parameter can be replaced by some vendor specific parameters in some CWMP data models (e.g. in tr-098-1-8-0). (Examples: internetGatewayDevice.LANDevice.1.WLANConfiguration.1.AssociatedDevice.1.X_HW_RSSI InternetGatewayDevice.LANDevice.1.WLANConfiguration.1.AssociatedDevice.1.X_MGTS_RSSI.)

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The Features of 802.11AC Standard. Is It Possible to Reach the Stated Speed?