Impact of frame tail effect on backoff procedure in modern dense Wi-Fi networks

As the density of Wi-Fi networks increases, interference becomes a major issue that can reduce performance depending on how the devices deal with it. Although Wi-Fi devices are expected to follow the IEEE 802.11 standard that defines channel access rules, there is no guarantee that vendors accurately implement them. This paper discovers a Frame Tail Effect, which is the unexpected behavior of many real Wi-Fi devices observed in dense deployments when they miss frame preambles and start to contend for the channel once the ongoing transmission ends. In this case, the considered devices do not wait for the standardized inter-frame space and try to access the channel immediately after the ongoing transmission. It increases the throughput for misbehaving devices but degrades the performance of other devices and prevents the support of real-time applications, which is the target of Wi-Fi 7. Although the Frame Tail Effect is observed only for Intel devices, it is crucial because the wireless cards of this vendor are widespread.