Wireless interference is currently the biggest factor affecting wireless networks, seriously compromising stability and transmission speed. As wireless networks become more prevalent in daily life, instances of wireless interference are also on the rise.
1. Large-scale WLAN networks generally use a thin AP architecture.
Detecting and mitigating wireless interference can be done by leveraging the APs that provide access services for scanning, or through a network composed of specialized devices. It can even be combined with dedicated handheld RF equipment for interference location, which is generally suitable for small networks or precise positioning within a limited area. For larger networks, monitoring typically requires deploying a dedicated network. The devices in this specialized network are usually APs in Monitor state or dedicated Sensors.
2. There are two modes of collaboration between the dedicated detection network and the access network.
One is the independent mode, where the devices of the detection network and the access network are managed by different controllers, with no interaction between them. The other is the integrated mode, where the devices of the detection network and the access network are managed by the same controller, and the detection network server can also process monitoring data from the APs of the access network. Compared to independent networks, integrated networks offer benefits such as unified management, full utilization of access network resources, and more convenient detection and positioning.
3. Detecting wireless interference essentially involves continuously monitoring over-the-air signals.
When the energy of an over-the-air signal exceeds a certain threshold, an FFT transformation is performed, and the result is further output to the WLAN receiver and various identifiers. The former determines whether the interference is a WLAN signal and further analyzes the MAC information, while the latter identifies the type of non-WLAN interference source.
4. Avoiding and mitigating wireless interference can greatly improve WLAN network performance. The industry has widely implemented these technical features, which further refine the entire network from details like 802.11 packet transmission or overall WLAN coordination to reduce mutual interference and effectively enhance WLAN performance. These technical features include: packet transmission rate adjustment, per-packet power control, and intelligent load balancing technology.
1) Packet transmission rate adjustment dynamically calculates the transmission rate for each packet. When sending a packet or retransmitting it to each client, the system considers factors like the client’s signal strength and historical transmission data to dynamically determine the appropriate current transmission rate.
When a transmission fails, different rate adjustment algorithms can be used based on the environment. In high-density environments, transmission failures are often caused by packet collisions. Using a very low transmission rate only increases the airtime of the packet, causing a wider impact range and a higher probability of further collisions. This can trigger other APs to further reduce their transmission rates, leaving the entire network in a state of low performance. In contrast, by using only high-speed retransmission, even if several attempts fail, upper-layer retransmission mechanisms can ensure the usability of upper-layer applications is not affected.
2) Like RRM’s dynamic adjustment of AP power, the goal of per-packet power control is to reduce interference between co-channel APs. When H3CAP sends each packet, it adjusts the transmission power of the current packet based on the client’s RF state. Per