Technology: Overview

For WLANs to be able to support mission-critical or time-sensitive applications, RF interference must be continuously monitored and the WLAN must dynamically adapt to mitigate the effects of the interference.  Bandspeed’s advanced RF interference monitoring and management technology is embedded into network devices to automatically detect and dynamically adjust Wi-Fi access point configurations to avoid interference and optimize performance.  Bandspeed AirMaestro Spectrum Analysis solutions employ a novel RF interference classification architecture, making them low-cost, high-performance, highly-scalable and field upgradable.

Wi-Fi has become the defacto standard for wireless connectivity within buildings.  With 802.11n, Wi-Fi solutions can now support distribution of high-throughput applications such as streaming video.  Wi-Fi networks, however, are prone to RF interference which can have drastic effects on the performance of the WLAN.  Some devices can completely disrupt an 802.11 channel even when they are a significant distance from the AP/client.

Common interferers in the 2.4 GHz Wi-Fi frequency band include:

• Bluetooth devices
• Microwave ovens
-Conventional
-Inverter
• Cordless phones
• Wireless video cameras
• Motion detectors

• Wireless game controllers
• Baby monitors
• Wireless pointing devices
• Zigbee devices
• RF Jammers

Depending on the type of interferer, its frequency profile, signal strength and location to the Wi-Fi communication devices, up to 100% of the WLAN network throughput can be lost due to this interference.

With users looking to deploy latency-sensitive applications such as voice over their Wi-Fi networks, better RF interference management solutions are needed.  Latency sensitive devices can suffer performance loss from RF interference even when the average throughput is sufficient to support the throughput requirements.  Even though voice calls require relatively little bandwidth, their latency and jitter requirements to support adequate call quality require solutions beyond higher throughput.  Quality of Service (QoS) standards support can help prioritize voice packets over video and data packets, but they are based on a Layer 2 mechanisms and do not help when the packets are delayed or blocked by RF interference. 

With the AirMaestro Spectrum Analysis technology, Bandspeed has redefined the architecture for RF interference classification solutions allowing it to be cost-effectively embedded in edge network devices.  Traditional solutions capture RF spectral information from the environment and provide this information to network processors or centralized server CPUs for feature extraction and signal analysis (see figures below).  The AirMaestro Embedded Signal Analyzer has an embedded classification engine that moves classification to the edge of the device/network.  This fundamental architectural change provides advanced interference monitoring and management, while requiring little from the network device CPU/memory or the local area network to which the device is connected. 

The AirMaestro Embedded Signal Analyzer is a purpose-built integrated circuit (IC) with a firmware-based classification engine supporting hardware-accelerated interference classification.  A time-domain analyzer and a frequency-domain analyzer are both integrated into the IC, allowing for more accurate interference classification that is not possible if only FFT/frequency-domain information is available.  While some WLAN ICs can provide some FFT/frequency-domain information, using the WLAN ICs to capture this information across the frequency band requires the WLAN interface to be taken out of service.  This is disruptive to the network and the users.  As a dedicated RF sensor with its own dedicated radio, the AirMaestro Embedded Signal Analyzer scans the RF environment independent of the WLAN ICs providing WLAN access.

Interference Classification Performed by a Remote Server/Appliance

Interference Classification Performed by a Network Device CPU

click image to enlarge

AirMaestro Spectrum Analysis Architecture

With interference classification in network devices, WLAN access points can dynamically adjust their channel settings to avoid real-time interference.  They can intelligently select the best channel based on historical information on the RF environment and specific adaptation policies selected by the user.