Making Sense of Signal Strength/Signal Quality Readings for Cellular Modems
Posted by Stephen Mammen
The first step in any successful cellular modem installation is verifying that the modem has a good connection back to the carrier network. This is especially helpful in that first "fingers crossed" moment when you are going live with a modem; good signal strength and signal quality makes modem deployment a smoother process.
While some graphical and qualitative ratings are provided by a cell modem's status page (e.g. green status/"Excellent"/"Good", red status/"Poor"/"Weak", etc.), more often one sees a numerical reading in dB or dBm. What do all these acronyms and negative numbers mean? This post aims to help with those questions.
Let's begin by defining our main acronyms of interest (along with the cellular technologies they are most useful for in parenthesis). There are certainly more measurements used in the industry, but let's keep it simple... signal strength and signal quality.
Signal Strength
- RSSI - Received Signal Strength Indicator (3G, CDMA/UMTS/EV-DO)
- RSRP - Reference Signal Received Power (4G LTE)
Signal Quality
- ECIO (Ec/Io) - Energy to Interference Ratio (3G, CDMA/UMTS/EV-DO)
- RSRQ - Reference Signal Received Quality (4G LTE)
- SINR - Signal to Interference-plus-Noise Ratio (4G LTE)