A Long-Range Narrowband RF Localization System with a Crystal-Less Frequency-Hopping Receiver

Emerging loT applications, such as asset tracking and first-responder rescue operation, require a new localization solution that achieves decimeter-level accuracy for long range (km) in GPS-denied indoor non-line-of-sight (NLOS) scenarios. Impulse-response ultra-wideband radar (IR-UWB) [1]–[3] can achieve high precision, but cannot operate in long distance NLOS conditions due to FCC-regulated transmit-power limits and severe pathloss through walls. Moreover, IR-UWB requires very high instantaneous power (> 70mW [2]) rendering it impractical for energy-constrained loT with small batteries and high internal resistance. Lower-power solutions with narrower bandwidth, based on WiFi [4] or Bluetooth [5], typically have a limited range of < 100m or are not operable in NLOS. A proprietary 80MHz OFDM-based solution [6] using an active-reflection IC achieved decimeter-level accuracy in NLOS conditions. However, it requires relatively high power consumption (62.8mW) with a limited range up to ~100m. Addressing this technological gap, we propose a new crystal-less low-power RF receiver with -115dBm sensitivity for long-distance (up to 483m) ranging in NLOS conditions with decimeter-level (~0.6m) accuracy.