Cellular Signals-of-Opportunity for RF Propagation Measurements with SDRs

Max Hollingsworth , Prasanth Prahladan, Michael G. Cotton , and Dirk Grunwald

Abstract:

Cell towers broadcast reference signals that mobile phones measure and report as reference signal received power (RSRP). Phones use the reference signal measurements for connectivity and handover between towers. This study explores the use of software defined radios (SDRs) for precise measurement of the power levels of these reference signals, showing them to be a rich yet untapped source for high-quality radio frequency (RF) propagation measurements. Given the widespread availability of cell towers, these signals are well-suited to generating the extensive RF channel data required by deep learning and ray-tracing models. However, questions remain about whether SDRs can achieve the level of accuracy RF researchers need for propagation model validation and enhancement. We present sdrRSRP, an open-source SDR toolset offering comprehensive, low-level control over reference signal measurements. This study shows that, with proper calibration, an SDR can deliver reference signal power measurements with an accuracy of ±3.5 dB. Additionally, we compare reference signal measurements to the continuous-waveform measurement technique commonly used by RF propagation engineers, demonstrating that the two methods yield measurements with negligible differences (< 1 dB).

Keywords: radio propagation; software defined radio (SDR); SDR; signals-of-opportunity

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