Signal analysis for IoT installations goes beyond checking whether a connection exists. Understanding the full RF picture at a site — which operators perform best, what the interference environment looks like, whether MIMO is working correctly, whether the antenna is pointed correctly — is the difference between an installation that works reliably for years and one that generates support calls from week one.
Signal metrics and what they tell you
| Metric | What it measures | Why it matters | Where to read it |
|---|---|---|---|
| RSRP | Reference signal power from serving cell (dBm/RE) | Primary coverage indicator. Determines whether signal is adequate. | All cellular technologies |
| RSRQ | Signal quality relative to total received power | Identifies interference. Poor RSRQ with good RSRP = interference problem. | LTE, NB-IoT, LTE-M |
| SINR | Signal vs interference plus noise ratio (dB) | Direct predictor of achievable throughput. High SINR = high modulation = high speed. | LTE, 5G NR, NB-IoT |
| CQI | Channel Quality Indicator (0-15) | Reported by modem to base station. Reflects modulation order in use. CQI 15 = maximum. | LTE |
| RSSI | Total received signal strength including noise and interference | Less precise than RSRP. Useful as secondary check. | LTE |
| PCI | Physical Cell Identity (0-503) | Identifies the serving cell. Used with CellMapper to verify tower and bearing. | LTE, 5G NR |
| EARFCN / ARFCN | Absolute Radio Frequency Channel Number | Identifies the exact frequency carrier in use. Confirms band selection. | LTE / 5G NR |
| Timing Advance | Distance compensation value (0-1282) | Proxy for distance to serving tower. High TA = distant cell = more path loss. | LTE |
Diagnostic framework: what to do with your readings
| RSRP | SINR | Diagnosis | Action |
|---|---|---|---|
| Good (>-90) | Good (>+10) | Strong, clean signal from nearby cell | Proceed. Record and certify. |
| Good (>-90) | Poor (<+5) | Interference. Strong signal but polluted channel. | Try directional antenna, band lock, or operator change. |
| Poor (<-100) | Good (>+10) | Weak signal but clean. Distant cell with no competition. | High-gain directional antenna. Confirm throughput adequate. |
| Poor (<-100) | Poor (<+5) | Weak and interfered signal. | Operator change essential. Consider alternative mounting position. |
MIMO port analysis
CellTester reads RSRP from each antenna port individually. For a 2×2 MIMO system, the two RSRP readings should be within 6 dB of each other. For 4×4 MIMO, the spread across four ports should be similarly balanced. Port imbalance above 10 dB indicates a fault: open circuit, poor connector, inadequate cable, or cross-polarisation issue. This fault is invisible to any tester that reads only the combined signal — CellTester reads per port.