Carrier and sampling frequency offset estimation for RF communication with crystal-less nodes
US11496174B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 2021 |
| Grant date | Nov 8, 2022 |
| Priority date | — |
| Expiry date | Apr 10, 2041 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0093
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
When the ultra-low power mm-scale sensor node does not have a crystal oscillator and phase-lock loop, it inevitably exhibits significant carrier frequency offset (CFO) and sampling frequency offset (SFO) with respect to the reference frequencies in the gateway. This disclosure enables efficient real-time calculation of accurate SFO and CFO at the gateway, thus the ultra-low power mm-scale sensor node can be realized without a costly and bulky clock reference crystal and also power-hungry phase lock loop. In the proposed system, the crystal-less sensor starts transmission with repetitive RF pulses with a constant interval, followed by the data payload using pulse-position modulation (PPM). A proposed algorithm uses a two-dimensional (2D) fast Fourier transform (FFT) based process that identifies the SFO and CFO at the same time to establish successful wireless communication between the gateway and crystal-less sensor nodes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.