60 GHz cnWave Antenna Alignment

Antenna Alignment feature is basically a tool to assist in optimizing alignment of the V3000 to V3000 in a PTP topology.

The antenna alignment tool is not a substitute for optical alignment. The optical alignment is the key to get the signal to within the +/-2deg azimuth and +/1deg Elevation window. Once we are in the window, to ensure we are optimal, the tool can be used to get away from the edge, corner or spurious beams.

The following points would describe how one can install and align the devices to achieve optimal performances.

  1. Customer to complete a Link Plan using Cambium Link planner. This would provide the information as to what the expected RSSI would be for the link. This should be used as target, when using the alignment tool.

  2. Enter the PTP topology in CnMaestro or device GUI, by creating the 2 Sites, assigning the V3K nodes and then setting up the wireless link between the 2 nodes.

  3. Assume at this stage either the nodes are already mounted or will be mounted at the sites.

  4. The installer should have access to the UI of the POP device or the controller managing this PTP link. What we will need to do is to enable the antenna alignment tool to kick start the alignment visual display. The alignment tool is available under the tools/Antenna Alignment as shown below.

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  5. The antenna alignment page default display will be as below.

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  6. To kick start the alignment tool, click on the Start Alignment button. When this button is pressed, a warning text would be displayed, indicating that the link ignition will be disabled. Basically, what this means is for alignment to run, the auto ignition needs to be disabled and if a link had already been established, it will be disassociated. Its ok to click the continue at this stage to start alignment process.

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  7. As soon as the alignment gets started, the RSSI time series will get populated as shown below.
    a. The screen starting from the top left labelled Local Node, displays the direction of arrival angle with respect to the local (POP) device.
    b. The screen on the top right-hand corner, labelled Remote Node, displays the direction of arrival angle with respect to the remote device.
    c. The cell marks the Direction of arrival, and the colour of the cell, represents the RSSI based on the heatmap scale given on the left.
    d. The bottom screen shows the RSSI time series, with the peak RSSI displayed with the latest data point on the right end of the plot.
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  8. The RSSI time series and the heatmap plots update every 6 seconds. This is due to the processing time taken for a complete sweep of all combinations of the beams and channels.

  9. During this alignment phase, the transmit power used will be the maximum configured power and the transmit power control will be disabled. Note if the installer has enabled the short-range installation in the radio configuration, the transmit power will be set to the minimum.

  10. The optimal RSSI should be reached when the beams are close to the central region as shown below. The RSSI on the time series should be very close to the Link planner predicted RSSI with an error of +/-5dB. If the time series reported RSSI, is more than 10dB out from the link planner’s predicted RSSI, this may indicate that the device has been mis-aligned and being picked up on the sidelobes or spurious beams. If one has this issue where, the cell is highlighted but the RSSI is more than 10 dB off the expected RSSI, it may be necessary to sweep beyond the current position in both Azimuth and elevation in turn to ride past the sidelobes.

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  11. How to make use of the Direction of arrival information to physically align the radios?

    11.1 Elevation mis-match example

    11.2 Azimuth mis-match example

  12. Once the desired alignment and RSSI has been achieved, the end alignment button could be pressed. Otherwise, once the 15minute cycle is over the alignment would end itself. Upon ending the alignment cycle, the ignition that was earlier disabled would be enabled to auto ignition and the link will be established.
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2 posts were split to a new topic: Problem with antenna alignment