airFiber - Good Signal but Bad Data Rates


This article describes what to do when your airFiber's signal strength indicators show excellent signal, but your device is not functioning as if it that were so. 

Table of Contents

  1. Symptoms & Solutions
  2. AF5 and AF5U Receive Sensitivity Table
  3. Related Articles

Symptoms & Solutions

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If the device shows good signal strength in all your Signal Strength indicators, but the airFiber5 link isn't able to modulate at maximum data rate for these signal levels (please check the Receive Sensitivity table for more information).

Possible Solutions 

Please make sure your link meets the following parameters:

  • Clear Line of Sight (LOS) between two sites.
  • No objects that could be causing reflection issues. If the antennas are installed in a roof with metal or any reflective surfaces, install the AF5 as high up as possible, at least 3meters (10ft) above any reflective surface (please read this Community post: Best location for a high performance link).
  • There's no high interference in the frequencies you are using, you can use airView to determine the best channel (available in firmware 2.1 or higher).
  • There's no signal mismatch among 4 signal strength indicators. Maximum deviation should be less than 4dB.
NOTE: Since firmware version 4.0, airFibers show an IDEAL POWER. This value is calculated by distance, gain, and output power. Your signal should match the IDEAL POWER value within 1-2dB. If it does not, you have a line of sight issue, or your alignment is off.

AF5 and AF5U Receive Sensitivity Table

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airFiber AF5/AF5U Receive Sensitivity

Spatial Streams Modulation Sensitivity (10 MHz) Sensitivity (20 MHz) Sensitivity (40 MHz) Sensitivity (50 MHz) FDD Capacity* TDD Capacity*
8x 256QAM -70 dBm -67 dBm -65 dBm -64 dBm 1024 Mbps 512 Mbps
6x 64QAM -77 dBm -74 dBm -72 dBm -71 dBm 768 Mbps 384 Mbps
4x 16QAM MIMO -84 dBm -81 dBm -79 dBm -78 dBm 512 Mbps 256 Mbps
2x QPSK MIMO -90 dBm -87 dBm -85 dBm -84 dBm 256 Mbps 128 Mbps
1x 1/2 Rate QPSK xRT -93 dBm -90 dBm -88 dBm -87 dBm 128 Mbps 64 Mbps
1/4x 1/4 QPSK xRT -95 dBm -93 dBm -92 dBm -91 dBm 32 Mbps 16 Mbps

Related Articles

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airFiber - How to Align an airFiber Antenna

airMAX - Using airView to Find the Best Channel

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