IPTel Solutions - Wi. Fi and The Problem With Radar. It sounds like a bit of a stretch for most people that Wi. Fi would have an issue with Radar. Microwave ovens are a pretty well known interferer with Wi. Cisco CleanAir Competitive Testing. This design can allow the channel to be. We used 5GHz DECT to record the signaling impact of frequency hopping. Cisco Secure Wireless Plant: Security and Quality of. Study sets matching "ccna 3 wireless" Study sets. When deploying a Cisco Cloud Wireless. Interference caused by two transmitters using the same channel. Frequency-hopping spread spectrum (FHSS) transmission is the repeated switching of frequencies during radio transmission to reduce interference and avoid interception. Cisco Wifi Channel Hopping PartFi in the 2. 4. GHz spectrum (they generate alerts for interferers, so we know they're there!)The bands in which Wi. Fi operate are known as unlicensed spectrum. This is different in each country that you operate – you have to tell your controller and APs in which domain they operate and the relevant channels are made available. While the 2. 4. GHz band tends to have a lot more interferers than the 5. GHz band (in addition to those Microwave ovens, there's Bluetooth headsets, some types of lights and so on), the 5. GHz band is also susceptible. Typically you don’t see too many interferers - 5. GHz is the preferred band for the reason that it generally has less interferences from outside sources than the 2. GHz band. We have though seen things like Mobile phone repeaters that use 5. GHz as a backhaul between repeaters, channel hopping and managing to obliterate several channels in the process. You may have seen a large radome (tallish building with a giant golf ball on top) near such facilities and it turns out that this can be operating in some of the 5. GHz spectrum. This is a programmed feature to allow Wi. Fi to make use of the same spectrum as a radar, but try not to either interfere with it – or be interfered by it. Unfortunately, the process is not exactly seamless, requiring APs to go offline and mark channels as non- useable. This can result in up to a 5 second silence (although it can be shorter), while the phone selects the next best AP and re- authenticates to it. If you have newer APs, you’ll find you can use the UNI II Extended band, which will allow some additional channels to be used – which depending on the region you’re in, might help. Alternatively, if you’re only using data functionality (and not voice), you can most likely get away with using DFS and the effect not get noticed.
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November 2017
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