Dual-band Harmonic and Subharmonic Frequency Generation Circuitry for Joint Communication and Localization Applications Under Severe Multipath Environment

The next generation of ultra-dense connected and automated wireless sensor networks (WSN) requires proximity intelligence for many of its applications, especially for identification and localization. This work presents the first bidirectional circuitry for Internet of Things (IoT) transponder that reciprocally generates harmonics and subharmonics, dual-band frequencies. A multi-band or wideband localization system is essential for future intelligent WSN to mitigate the influence of multipath signals for indoor dense environment. The proposed frequency generation circuitry is based on the novel nonlinear ring resonator (NRR) operating based on standing wave resonation. The proposed NRR generates two sustainable oscillation frequencies based on the periodicity of the nonlinear circuit in the ring configuration. Due to the symmetry and reciprocity of the ring layout, the two bidirectional ports can excite the circuit at the two opposite nodes while maintaining the required boundary conditions for oscillation. The sustainable resonance conditions occur by creating zero, short impedance, or pole, infinite impedance, at subharmonic and harmonic excitation ports. The NRR circuit consumes zero DC power and covers two communication frequency plans interchangeably, which makes it a premier technique compared to the conventional ultra-wideband (UWB) localization system and conventional single-band nonlinear passive circuitry. The latter is narrowband due to the tunning limitation of the nonlinear varactor while the former is power-hungry approach with complex hardware requirements.