A frequency offset recovery algorithm for crystal-less transmitters

In the growing market of low-cost, low data-rate wireless applications there is a significant motivation to implement crystalless wireless nodes, which will reduce costs and form factor. Several applications benefit from an asymmetric wireless scenario in which the transmitter is required to be cheap, small and ultra-low power, while the receiver will be a residential gateway (RG) or a basestation with a virtually unlimited power budget and relatively higher allowable cost and form factor. In this scenario, while the transmitter will be implemented as a crystal-less node, all the required complexity in the frequency synchronization can be shifted to the RG. Nevertheless the acquisition time should be short compared to the transmission time to save power in the transmitter, and frequency offset in the MHz range should be reduced to few kHz. A new algorithm, which can easily recover frequency offsets larger than the data-rate and which can address the aforementioned issues, is proposed in this paper.