Troubleshooting through Spectrum Analysis

Interference between wireless devices increases significantly as more devices operate in the same frequency band. As more devices share the same channel, they may experience co-channel interference (CCI) and adjacent channel interference (ACI) resulting in their having to wait for each other’s transmissions, increasing latency and reducing throughput.
Spectrum analysis allows you to remotely visualize the radio frequency (RF) environment and detect interference patterns across the 2.4 GHz and 5 GHz bands. It helps identify both Wi-Fi and non-Wi-Fi sources of interference within your network, allowing you to view amplitude and utilization across channels, pinpoint where interference is strongest, and monitor how the patterns evolve over time.
    Note:
  • Spectrum analysis is currently not supported on the 6 GHz band.
  • Keep spectrum captures brief. During active spectrum scans, connected clients may be offloaded to nearby APs to avoid service disruption and new Wi-Fi clients cannot join the selected AP. The AP will return to full service after the scan stops.

APs which are put in spectrum-mode transmit data to the controller, which in turn displays the data in spectrum-mode for analysis.

  1. From the controller GUI main menu, select Monitor > Troubleshooting & Diagnostics > Troubleshooting.
    This displays Troubleshooting window as shown in the following example.
  2. Select Spectrum Analysis from the Type drop-down menu in section 1.
  3. Click Select in the AP MAC Address field in section 2. In the resulting Select AP window, expand the network hierarchy as necessary, click the checkbox for the desired AP, and click OK.
  4. Select the radio frequency from the Radio drop-down menu in section 3. Available values are 2.4GHz or 5GHz; 6GHz is not yet supported.
    If you select 5GHz, then an additional Segment field appears; select Lower (channels 36 through 64), Middle (channels 100 through 144), or Upper (channels 149 through 165) from the drop-down menu.

    Configure the data visualization settings for the following graphs (such as displaying amplitude or utilization, displaying averages or maximums, and coloring by amplitude or density): :

    • Real-Time FFT and Spectrum Usage: This chart displays a black line to reflect the Real-Time Fast Fourier Transform (FFT) data and a color-based view to show collections of spectrum usage data points, all collected every 2 seconds across all channels in the selected band. If you view by real-time Amplitude (signal strength), then the chart can display either the Average or the Maximum amplitudes of energy measured across the band for that sample period and the chart can display spectrum usage color-coded data points by Amplitude or Density. As more spectrum usage data samples are measured at a specific frequency and amplitude coordinate, the color shown at that coordinate will change. If you choose to view colors by amplitude, the warm colors depict higher amplitude and cool colors lower amplitudes. If you view the colors by density, the warm colors depict a high number of samples at a given coordinate and cool colors show low number of samples at a given coordinate. If you view by real-time Utilization (duty cycle), then the chart displays a black line reflecting the percentage (%) at which the frequency is utilized across the channels, relative to the threshold. The utilization threshold is configurable but the default is -85dBm.
    • Swept Spectrogram: This chart displays a waterfall of color over time, where each horizontal line in the waterfall represents one sample period (2 seconds) of color-coded data points across the channels in the selected band. The full waterfall display spans up to 2 minutes of time (60 samples at 2 seconds each). There are two display options for the spectrogram chart:
      • Amplitude: Shows either the Average or Maximum amplitudes of energy measured across the band for that sample period.
      • Utilization: Shows the percentage (%) at which the frequency is utilized relative to the defined utilization threshold. The utilization threshold is configurable but the default is -85dBm.

  5. After you select the parameters that you want to use to view the graphs, click Start.

    Troubleshooting - Spectrum Analysis

  6. Click Stop to terminate collection of spectrum analysis data. The graphs remain on-screen, allowing you to continue view and change the display parameters for the collected data.
    Note: The data and graphs are not persistent and will disappear when you start a new capture or leave the Troubleshooting page.
Parent topic: Troubleshooting Tools