Spectrum Protection from Micro-transmissions Using Distributed Spectrum Patrolling

RF spectrum is a limited natural resource under a significant demand and thus must be effectively monitored and protected. Recently, there has been a significant interest in the use of inexpensive commodity-grade spectrum sensors for large-scale RF spectrum monitoring. The spectrum sensors are attached to compute devices for signal processing computation and also network and storage support. However, these compute devices have limited computation power that impacts the sensing performance adversely. Thus, the parameter choices for the best performance must be done carefully taking the hardware limitations into account. In this paper, we demonstrate this using a benchmarking study, where we consider the detection an unauthorized transmitter that transmits intermittently only for very small durations (micro-transmissions). We characterize the impact of device hardware and critical sensing parameters such as sampling rate, integration size and frequency resolution in detecting such transmissions. We find that in our setup we cannot detect more than 45% of such micro-transmissions on these inexpensive spectrum sensors even with the best possible parameter setting. We explore use of multiple sensors and sensor fusion as an effective means to counter this problem.