Chirp Spread Spectrum Receiver Early Message Rejection
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Solution Overview
Problem
Chirp spread spectrum (CSS) systems face challenges in data alignment and message rejection due to noisy wireless channels, leading to low data rates and false positive acquisitions, which limit the types of data that can be communicated over long ranges.
Innovation Solution
A method for data alignment in CSS using training chirps processed through fast-Fourier transform (FFT) pipelines, where accumulated FFT results exceed a detection threshold to determine symbol alignment, and multiple opposite chirps encode identifiers for early message rejection, enabling robust symbol and data alignment even in noisy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional CSS systems process messages fully before rejection, then message reliability is improved, but latency and false positive acquisitions increase
Solution Approach 1:
The patent applies preliminary action by performing identifier decoding and validation on opposite chirps before fully processing the message. The system decodes identifiers from opposite chirps in the preamble, validates them against expected values, and performs early message rejection if validation fails, avoiding the need to fully process invalid messages and reducing latency.
2Device complexity
If CSS systems use single chirp identification, then device complexity is reduced, but the range of identifiers is limited
Solution Approach 1:
The patent applies segmentation by dividing the identification process into multiple independent chirps within the preamble. Instead of using a single chirp for identification, the system uses multiple opposite chirps, each carrying identifier information. This segmentation allows the system to represent a much larger range of identifiers while keeping each individual chirp processing simple.
3Measurement precision
If CSS systems accumulate FFT results from multiple training chirps, then symbol alignment precision is improved, but processing time increases
Solution Approach 1:
The patent applies partial action by accumulating FFT results from a specific number of training chirps (e.g., 8 or 16 chirps) rather than processing all available chirps. The system accumulates results from sufficient chirps to achieve reliable symbol alignment and detection threshold exceeded, then stops accumulation and proceeds to opposite chirp processing, balancing precision with processing time.
Data Source
AI summary
A chirp spread spectrum (CSS) receiver may reject, based on multiple data alignment chirps that includes an attribute identifier that is a mismatch to one or more preconfigured identifiers, a message early and before fully receiving/decoding the message. The multiple data alignment chirps may enable usage of a larger range of IDs than a single chirp signal. A receiver may receive a sequence of training chirps for symbol alignment followed by multiple opposite chirps for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT) and the resulting values accumulated until a threshold is exceeded. Using symbol alignment from the training chirps, the receiver may decode multiple opposite chirps that indicate data alignment and comprise an encoded identifier. The receiver may reject the message and terminate further message processing based on the encoded identifier being a mismatch to preconfigured identifiers or attributes indicated by the encoded identifier.