RSSI (Received Signal Strength Indicator) is a measurement of the Radio Frequency (RF) power present in a received radio signal at the mobile device. It is generally expressed in dBm and the best cellular throughput is achieved when the Opengear device and/or its antennas are positioned to maximize RSSI.
-100 dBm or less: Unacceptable signal, check antenna connection
-99 dbm to -90 dBm: Weak signal
-89 dbm to -70 dBm: Medium to high signal
-69 dBm or greater: Strong signal
There are three ways to check signal strength, via the Opengear web UI, the command line, and via the chassis LEDs.
Before measuring signal strength, configure your cellular connection to ensure the readings are measuring the appropriate carrier and band.
Login to the Opengear web UI as root or an admin user and click Status -> Statistics -> Cellular.
This displays the current state of the cellular modem, including RSSI labeled either LTE RSSI (dBm) or Received Signal Strength Indication (RSSI in dBm).
Login to the Opengear CLI as root or an admin user and run:
cellctl -l -s
This displays the current state of the cellular modem, including RSSI labeled either signal-lte-rssi or rssi.
If your Opengear device has signal strength LEDs, refer to the following:
No LEDs lit: Unacceptable signal, check antenna connection
1 LED lit: Weak signal
2 LEDs lit: Medium to high signal
3 or 4 LEDs lit: Strong signal
The LED status is updated every 5 seconds.
Maximizing cellular signal strength
1. It may be useful to undertake a signal strength site survey to profile your site prior to installation. Specialist equipment is available, however a standard cellular phone with a SIM from the same carrier will typically suffice.
2. Antenna selection and placement can drastically affect signal strength:
- Ensure both MAIN and AUX antennas are properly connected
- Use an antenna extender as necessary
- Place the antenna outside any metal racks and cabinets, which may induce a Faraday cage effect
- Keep the antenna and antenna cable away from AC wiring and other interference, such as other electrical or radio devices
- Select the optimum placement for the antenna, e.g. close to an exterior window or to a higher point in the building, on top of tall cabinets, etc.
- Be aware of the location of the carrier's cellular tower and position accordingly
If you can only obtain a marginal signal using the standard antenna, consider a third-party high gain or directional antennas, extenders or boosters – for more information refer to this article.
3. Try a different carrier. Opengear multicarrier models support pre-provisioning with dual SIMs, so that each carrier can be tested and the optimal carrier selected during device deployment.