![]() Negative Impact of Heavy Channel EnergyĪs a result, it blasts the spectrum continually and the channels are heavily loaded with energy that cannot be decoded by a Wi-Fi transceiver.ĭue to the high non-Wi-Fi energy, the access point in the area holds back sending its beacons. More importantly, it uses a proprietary technology which does not follow the Wi-Fi Listen-Before-Talk principle. It also has an output power of 115mW (20.6 dBm). the Cel-Fi repeater found uses the 5 GHz band to communicate between the Network Unit and the Coverage Unit. When he does, he finds a Cel-Fi cellular repeater is being used for indoor cell phone signal boosting. With this technique, it's clear to see in the spectrum chart below that interference is strongest between antennas 1 and 5.Īt this point, all the network engineer has to do is go to the location and make a visual inspection. An integrated compass allows for correlating antenna numbers with the customer's office layout. Therefore, with the help of antenna directivity, the source of the interference can be located. The Sapphire Eye 2100 uses an array of six 60-degree directional antennas with spectrum analysis. ![]() In fact, the spectrum analysis also shows another band with a similar increase, but luckily in this case, there are no nearby access points using that channel. The access point named LWAP-04, which is the one that originally alerted our customer with a Beacon Availability alarm, uses channel 60. Below is a waterfall spectrum graph which shows a significant RF power increase on channels 56-60. With only a spectrum analyzer, it’s difficult to say whether this new energy is just busy Wi-Fi traffic or something else, because the bandwidth looks similar to 40 MHz Wi-Fi channel. A nice benefit of 7SIGNAL is that it runs a periodic spectrum test throughout the day and night and stores the data for later analysis. What About a Spectrum Analyzer? Periodic Spectrum Test However, as seen in the chart below, the system indicates that the access point had remained on channel 60 despite the high noise level. Most Wi-Fi access point vendors promise that with RF automation enabled, APs will automatically change channels when they detect interference. We are NOT referencing any specific Wi-Fi vendor. Our customer was using RRM, as recommended by their WLAN vendor. ![]() We use RRM as general term here for Radio Resource Management. Something is blasting the spectrum on a large swath of channels so hard, that not even beacons can cut through the noise. As you can see in the chart below, the Beacon Availability alarm corresponds precisely with a dramatic increase in noise on certain channels. It's important to recognize that the customer's WLAN controller software was not able to detect this.Īs a next step, we took a closer look at the Noise Monitor in 7SIGNAL as a quick and simple way to detect an increased noise floor. The chart below illustrates this perfectly as the Beacon Availability KPI went from 100% to zero. Our customer received an automated Wi-Fi performance alert from the 7SIGNAL system indicating that access point beacons were no longer detected. This is problematic because not all of them play by the same set of rules as Wi-Fi. Different technologies exist and some of them utilize the 5 GHz U-NII frequency bands for internal system communications. Their job is to receive the cellular signal and then amplify it. To address the issue of low indoor signal strength, you can also use indoor cell phone signal boosters. But none of these are quick and simple alternatives. Other potential solutions include redirecting the base station antenna, adding more base stations, and finally, you can build-out indoor coverage with a distributed antenna system ( DAS) or with more indoor base stations. However, this quickly leads to an unbalanced radio link and an increase in co-channel interference, because when the terminal receives a good signal level from the base station but base station does not receive a sufficient signal back from the terminal, then your connection problems remain. Increase Power Outputįirst, they could increase the base station's output power. To address the issue, a cellular operator has a few different options. How to Improve Indoor Cellular CoverageĬellular indoor coverage is a common problem. Using our Wi-Fi performance management system, one of our customers recently discovered how their indoor cell phone signal booster was completely trashing their 5GHz spectrum, rendering one poor neighboring access point completely worthless.
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