Do the Wi-Fi airwaves need to be scanned 24x7? Why or why not?





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Both mobile spectrum analyzers and 24 X 7 distributed spectrum solutions (sensors with built-in spectrum analysis adapters) have significant benefits and advantages. The choice between them may ultimately come down to the preference of the user and their business and/or technical requirements for their WLAN deployment. These include:
1) Need for remote monitoring as compared to on-site monitoring, which may be influenced by the number of sites that need to be monitored and the availability of IT staff members
2) Budget for RF spectrum monitoring
3) Need for 24 X 7 monitoring for security purposes
4) Number of RF related problems occurring in the network
5) Time between RF spectrum scans
6) Need for pin-pointing the location of the interference source

The use of mobile spectrum analyzer solutions,like AirMagnet Spectrum XT,in the WLAN deployment phase is mandatory. Results from the initial RF spectrum sweep go a long way in making the right choices for a successful and optimally performing WLAN. RF energy levels and the presence of interference sources detected by the spectrum analyzer influence the location of the APs and their channel and power settings. Mobile solutions also work great when you are trying to physically locate interference sources, so that they can be stopped from operating or can be quickly removed from the facility. So, even if the source is hidden inside a drawer, on top of a bookshelf or is built inside some other office equipment or fixture, the “Geiger-counter” based device locator feature can lead the IT staff member to the exact location. Also, many of the non Wi-Fi interference problems are location specific and require spectrum solutions to travel to the location of reported problems. For example, with a mobile solution, one can precisely measure the level of interference and other RF specific parameters at a location, instead of relying on reports from sensor hundreds of feet away.

A 24 X 7 distributed monitoring solution, which includes RF spectrum sensors reporting back to a centralized server, has its own advantages. Sites that need remote monitoring due to unavailability of IT staff or lack of RF expertise at every location may benefit from a centralized spectrum solution. Some corporations may also mandate continuous monitoring to detect any unauthorized activity, such as layer 1 DoS attacks from unintentional or intentional transmitters (like RF jammers),or may implement a “no wireless or RF” policy (commonly seen in Federal or military deployments) and need to be alerted to the presence of RF emitting devices. The use of mission-critical applications (for example healthcare applications or even voice over WLAN) warrant for continuous monitoring of the network. Distributed 24 X 7 spectrum solutions, such as AirMagnet Enterprise, send alerts (emails, page messages, etc.) to the IT staff as soon as interference sources are detected and even allow saving of RF data as forensic information for post-capture or post-incident investigation.

AirMagnet provides best of both world industry-leading solutions (i.e. 24 X 7 distributed solution and mobile spectrum analyzers) to provide users with a complete arsenal of solutions to deal with any interference related problem. Users commonly start with the mobile spectrum solution, and, realizing the potential and benefits of spectrum monitoring and management in their network, move to the distributed solution as the number of sites that need to be monitored increases.

Yes. An initial or periodic scan is insufficient because 1) new devices can be introduced at any time as someone walks into the enterprise carrying a device, 2) lots of devices are used intermittently (ex. cordless phones) and might be missed during a periodic scan.

Also, 24x7 scanning gives you: pro-active alerting as soon as a problem occurs and history over time of how often similar problems occur.
History is also important when you have a trouble ticket from a day or two ago, and want to understand what was happening in the RF during that window.

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