3G UMTS Signal Strength Reference Guide

3G UMTS Signal Strength Reference Guide main image 3G UMTS Signal Strength Reference Guide image

The following indicators are used to determine the quality of a 3G signal.  The charts indicate rough guidelines as to what constitutes a particular level of quality, ranging from excellent to unusable. 

To avoid performance issues none of these values should be in, or dip into the red.  Optimal performance is achieved when all values are in the green.

Diagnosing Signal Issues

There are many reasons why signal performance can vary significantly, which is why it is important to accurately diagnose your signal issues so that the correct solution can be implemented.  For more information on how to diagnose signal issues see our Guide to Understanding Poor Mobile Coverage, which contains advice that applies to mobile phones and mobile data devices.

RSSI - Received Signal Strength Indication

RSSI Quality Description
≥ -75 dBm Excellent Strong signal enabling maximum data capacity
≥ -80 dBm Good Good signal and speeds with no dropouts expected
≥ -90 dBm Fair to Poor Fair/usable signal with possibility of dropouts and slowdowns
≤ -112dBm Unusable No usable signal - expect frequent disconnections and sluggish performance

 

RSCP - Received Signal Code Power

RSCP Quality Description
≥ -60 dBm Excellent Strong signal enabling maximum data capacity
≥ -75 dBm Good Good signal and speeds with no dropouts expected
≥ -85 dBm Fair to Poor Fair/usable signal with possibility of dropouts and slowdowns
≤ -125 dBm Unusable No usable signal - expect frequent disconnections and sluggish performance

 

Ec/Io - Signal to Noise Ratio

This is a ratio of the received chip rate energy (Ec) to the interfering co-channel (Io); in other words, it is a signal to noise ratio.  Because a payload is transmitted over multiple chips, as Ec/Io becomes poorer, some chips may not make it to the destination or may need to be retransmitted multiple times before the message can be successfully decoded.  It is also a factor used by the mobile network to determine preciesly when to perform handover of user equipment to another base station.

Ec/Io Quality Description
≥ -6 dBm Excellent Strong signal enabling maximum data capacity
≥ -10 dBm Good Good signal and speeds with no dropouts expected
≥ -15 dBm Fair to Poor Fair/usable signal with possibility of dropouts and slowdowns
≤  -20  dBm Unusable No usable signal - expect frequent disconnections and sluggish performance

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