ePMP: Troubleshooting the radio link

This post describes how to test the link when there is no radio communication, when it is unreliable, or when the data throughput rate is too low. It may be necessary to test both the AP and the SM.

Module has lost or does not establish radio connectivity

Step

Action

1

Check that the AP and SMs are configured with the same Frequency Carrier.  Also, if operating in a region where DFS is required, ensure that the SM’s Frequency Carrier List contains the frequencies configured in the AP’s DFS Alternate Frequency Carrier 1 and DFS Alternate Frequency Carrier 2 fields.

2

Check that the Channel Bandwidth is configured the same at the AP and at the SM

3

On the AP, verify that the Max Range setting is configured to a distance slightly greater than the distance between the AP and the furthest SM that must register to the AP.

4

Check that the AP’s Synchronization Source is configured properly based on the network configuration.

5

Verify the authentication settings on the AP and SM.  if Authentication Type is set to WPA2, verify that the Pre-shared Key  matches between the AP and the SM Preferred AP List

6

Check that the software at each end of the link is the same version.

7

Check that the desired AP’s SSID is configured in the SM Preferred AP List.

8

On the SM, check the DL RSSI and DL CINR values. Verify that for the SM installed distance, that the values are consistent with the values reported by the LINKPlanner tool.

9

Check Tx Power on the AP and SM

10

Check that the link is not obstructed or the AP/SM misaligned.

11

Check the DFS status page (Monitor, System Status) at each end of the link and establish that there is a quiet wireless channel to use.

12

If there are no faults found in the configuration and there is absolutely no wireless signal, retry the installation procedure.

13

If this does not work then report a suspected AP/SM fault to Cambium Networks.

Link is unreliable or does not achieve data rates required

Step

Action

1

Check that the interference has not increased by monitoring the uplink and downlink CINR values reported in the AP page Monitor, Wireless Status

2

Check that the RSSI values reported at the AP an SM are proper based on the distance of the link – the LINKPlanner tool is designed to estimate these values.

3

Check that the path loss is low enough for the communication rates required.

4

Check that the AP or SM has not become misaligned.

5

Review your Quality of Service configuration and ensure that traffic is properly classified and prioritized.

Module Has Lost or Does Not Gain GPS Synchronization

To troubleshoot a loss of sync, perform the following steps.

Step

Action

1

If the AP is receiving synchronization via CMM, verify that the CMM is properly receiving sync via its attached GPS antenna (see PMP Synchronization Solutions User Guide).  Verify that the cables from the CMM to the network switch are at most 30 Ft (shielded) or 10 Ft (unshielded) and that the network switch is not PoE (802.3af) capable.

2

If the CMM is receiving GPS synchronization pulses, verify that the AP’s Synchronization Source is set to CMM and that the AP’s GPS status bar icon is lit green.

3

If the AP is receiving synchronization via its internal GPS module and an external GPS antenna, verify the cabling from the AP to the GPS antenna, and verify that the AP’s Synchronization Source is set to GPS.