Interference Measurements in IEEE 802.11 Communication Links Due to Different Types of Interference Sources

The number of wireless devices (smartphones, laptops, sensors) that use the 2.4 GHz ISM band is rapidly increasing. The most common communication system in this band is Wi-Fi (IEEE 802.11b/g/n). For that reason coexistence between Wi-Fi and other systems becomes more and more important. In this paper we have investigated the influence on Wi-Fi communication for different interference sources, i.e., wireless Audio/Video (A/V) transmitter, microwave and Bluetooth. A measurement tool has been developed to measure this influence both at the Physical (PHY) Layer and at the link layer to assess the overall Quality of Service (QoS). At link layer the tool allows to analyze the received packets types and sub fields; a sophisticated approach to analyze interference mechanisms compared to traditional packet sniffers that focus on throughput and packet error rate only. In addition, this tool allows to identify the type of interference source based on the occurring interference mechanisms at these lower two layers of the OSI protocol stack. The experimental results show severe impact of A/V transmitters which causes significant overall QoS degradation of WiFi communication in contrast to microwave and Bluetooth interference.