RSSI stands for Received Signal Strength Indicator. It is an estimated measure of power level that a RF client device is receiving from an access point or router.
At larger distances, the signal gets weaker and the wireless data rates get slower, leading to a lower overall data throughput. Signal is measured by the receive signal strength indicator (RSSI), which in most cases indicates how well a particular radio can hear the remote connected client radios. For point-to-(multi)point applications, the optimal RSSI on each end of the wireless link is between -48 dBm and -65 dBm to achieve the highest possible data rates.
- The best practice is to pre-configure the radios with a transmit power of 15 dBm and validate that a link is properly established (which serves to validate security and MAC address settings as well). Once the access points are physically mounted in place, look at the RSSI readings on each radio and adjust the transmit power settings on each side of the link up or down to get the RSSI to within the -48 dBm to -65 dBm range
- If the signal strength is greater than -35 dBm (typical for wireless links under 50 feet), then the electronic amplifiers get saturated because the signal is too strong, which degrades throughput performance. In such scenarios, turning down the power to minimum (11 dBm) may be insufficient, and if so we recommend purposely misaligning the antennas.
- If the signal strength is less than -75 dBm (typical for very long distance shots over 4 miles), it may be difficult to sustain a link reliably or to achieve high throughputs, especially in the presence of external interference. For long distance shots, EnGenius recommends using laser tooling to optimize the antenna alignment so as to maximize the signal.
Desired RSSI: | -40 dBm to -50 dBm |
Usable RSSI: | -35 dBm to -70 dBm |
Above | -35 dBm: Signal is too strong, saturated amplifiers |
Below | -70 dBm: Signal is too weak, subject to external interference |
Visualize your projects RSSI through the subscription-free network design tool, ezWiFi Planner. Try it now to measure your projects WDS bridge connectivity and projected coverage.
http://community.engeniustech.com/topic/938-what-is-rssi-and-its-acceptable-signal-strength/
Comments
4 comments
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I have a couple of EnGeniusAC5 units about 75 feet apart, showing -17dBm between them and throughput is horrible. I tried AUTO mode, and turning the power down to minimum. Still horrible. Tried misaligning the dishes in an urban area and some other device would try to connect to one end from God knows where and got weird connectivity issues and throughput continues to be horrible. Final solution? Reoriented them both at each other, bought a metalized cloth off Amazon, made a bag of sorts, even comes with metalized cloth tape, hung it over one of the nodes and viola! knocked the signal down to -60dBm, and I can get darn near 700MB throughout (out of a theoretical 866MB throughput). As I am an RF engineer by trade, seriously thinking about popping the open (they are long since out of warranty) and installing a 20dB to 30dB attenuator internally in each (yes I know I could double it on one end but I would prefer to make them identical to help with inband interference from other devices in the area.) and doing away with the bag since it isn't a very attractive solution. Good luck whatever you do! -Jim-
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The second paragraph suggests -48 dBm to -65 dBm, but the summary at the end suggests -40 dBm to -50 dBm. Which is it? Is this range the same for all your products?
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