Wireless Interference detection and elimination measures

WLANIt is no longer just a simple network access method. Many important applications of enterprises, such as voice, video, and location services, are gradually deployed on wireless networks. Even for normal network access, users also hope that the higher the bandwidth, the better. As applications increase,Wireless InterferenceThe impact of problems on the Quality of network services is becoming increasingly prominent.

Wireless Interference detection

Large-scale WLAN networks generally adopt a thin AP architecture. The detection and reduction of wireless interference can be performed by scanning the AP that provides access services, or by a network composed of dedicated devices, you can even use a dedicated handheld RF Device to locate interference. The latter two fall into the scope of spectrum analysis. The positioning of handheld RF devices is generally suitable for precise positioning of small networks or small areas. For large networks, a dedicated network is usually needed for monitoring. In this dedicated network, the device is generally in the Monitor status AP, or a dedicated Sensor. These devices send data from the empty port to the server for analysis, storage, and processing.

There are two ways to collaborate between a specialized detection network and a network that provides access. One is independent of each other, that is, the devices on the detection network and those on the access network are managed by different controllers, there is no interaction between the two. The other is the integration method, that is, the device of the detection network and the device connected to the network are managed by the same controller, the server that detects the network can also process monitoring data from the AP connected to the network. Compared with an independent network, an integrated network features unified management, full use of network resources, and convenient detection and positioning.

Wireless Interference detection is to continuously monitor air port signals. When the signal energy of the blank port exceeds a certain value, the FFT is performed and then output to the WLAN receiver and Classifier). The former checks whether the interference is a WLAN signal and further analyzes the MAC information, the latter determines non-WLAN interferenceSource Type 5 ).

Measures to avoid and reduce Wireless Interference

Wireless Interference avoidance and reduction can greatly improve the performance of WLAN networks. These technical features are widely achieved in the industry. H3C has innovated the following technical features. These technical features further improve the entire network, reduce mutual interference, and improve the performance of the WLAN Network from details such as 802.11 message transmission or WLAN Network coordination. These features include packet transmission rate adjustment, packet-by-packet power control, and smart load balancing.

1. message transmission rate adjustment

The message transmission rate adjustment dynamically calculates the transmission rate of each packet. Each time each Client sends a message or re-transmits a message, H3CAP dynamically calculates the appropriate transmission rate of the current message based on the Client's signal strength and Historical Transmission Information. When sending fails, you can use different rate adjustment algorithms based on different environments. For example, in a high-density deployment environment, when a packet fails to be sent due to a high rate, the packet will not be resent at a very low rate. This is because in a high-density environment, packet transmission failure is generally caused by a message conflict. When a very low packet is sent, only the length of the blank port of the sent packet changes, the impact scope is greater, leading to more potential conflicts, and other APs further reduce the transmission rate, making the entire network in a low-performance state. However, only high-speed retransmission is adopted. Even if multiple sending attempts fail, the upper-layer retransmission mechanism can be used without affecting the availability of upper-layer applications.

2. Package-by-package Power Control

The goal of One-package power control is to dynamically adjust the AP Power in the same way as that of RRM, to reduce interference between the same-frequency AP. When each message is sent, H3CAP adjusts the sending power of the current message according to the RF status of the Client. Package-by-package power control can minimize the impact of signal transmission and ensure AP coverage.

3. Smart Load Balancing

The smart Server Load balancer technology is different from the simple Server Load balancer technology. The wireless Controller determines the location of the Client. Only clients in the two AP overlapping regions can start the Server Load balancer, connect the Client to a low-Load AP. Smart load balancing can reduce the load of a single AP, thus reducing the proportion of Client conflicts under this AP.

Because of the difference in the network card used by the user or other differences in the location), the performance of users under the same AP is often different, and the speed of individual users is often very low. If an AP has a high-speed user and a low-speed user, the chances of empty ports being snatched are almost the same, as a result, each time the high-speed rate completes sending its own data, it will have to wait for the low-speed user to send its data slowly. Therefore, the performance of high-speed users is greatly restricted by low-speed users. Therefore, by reducing the time occupied by low-rate users and reducing their impact on the blank port, the throughput performance of the entire network is improved.

The detection and positioning of WLAN interference has been able to be centrally monitored and managed. RF management is no longer a solution only for professionals, and can be easily done by general network managers. In the future, with the development of WLAN transmission systems and the improvement of other hardware technologies, WLAN interference will have more ways to overcome and users will have a more perfect WLAN experience.