Swept-Tone Interferer Estimation in Frequency-Hopped Systems
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Solution Overview
Problem
Existing wireless communication systems face challenges in effectively estimating and mitigating swept-tone interferers, which are characterized by fast varying instantaneous frequencies, due to their broadband nature and interference across multiple frequency hops.
Innovation Solution
The approach models swept-tone interferers as magnitude-periodic signals with a common pulse shape over the observation or hop bandwidth, estimating the period and phase rotations to generate an interference estimate, which is then subtracted from the received signal to produce an interference-mitigated signal of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive notch filters are used to track instantaneous frequency of swept tone, then mitigation capability is improved, but device complexity increases
Solution Approach 1:
The patent creates a model copy of the swept-tone interferer by estimating its parameters (frequency, sweep rate, amplitude) and generating a synthetic replica. This model interferer is then subtracted from the received signal to achieve cancellation. This approach avoids the complexity of adaptive filtering by using parameter estimation and signal reconstruction instead.
2Measurement precision
If joint estimation of chirp signal parameters using least-squares is employed, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent segments the chirp signal estimation into distinct steps: first estimating the frequency and sweep rate parameters, then using these to determine the amplitude and phase. This segmented approach breaks down the complex joint estimation problem into simpler sequential steps, reducing computational complexity while maintaining precision.
3Object-affected harmful factors
If tone prediction using adaptive filter structure is used, then periodic interference cancellation is improved, but adaptability to non-periodic signals deteriorates
Solution Approach 1:
The patent changes the approach from adaptive filtering to parameter-based modeling. By estimating fundamental parameters (frequency, sweep rate, amplitude, phase) of the interferer, the system can generate an accurate model that adapts to different signal characteristics. This parameter-based approach works for both periodic and non-periodic swept-tone signals, improving versatility.
4Measurement precision
If swept-tone interferer modeling as magnitude-periodic signal is implemented, then estimation accuracy is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary estimation of the interferer parameters (frequency, sweep rate) first, then uses these pre-estimated parameters to construct the magnitude-periodic model. This preliminary action allows the system to establish the model structure before detailed signal processing, improving efficiency by avoiding iterative optimization during the main processing stage.
Data Source
AI summary
The estimation and mitigation of swept-tone interferers includes receiving a composite signal comprising a signal of interest and a swept-tone interferer over an observation bandwidth or a hop bandwidth in a frequency-hopping system. The estimation of the interfering signal may be based on modeling the interferer as a magnitude periodic signal comprising non-overlapping, contiguous epochs, where each epoch may comprise a common pulse shape and a distinct phase rotation. The modeling may be based over the observation bandwidth, the hop bandwidth, or after combining the signal over all the frequency hop bandwidths. The period of the magnitude-periodic signal may be initially determined, and the common pulse shape and each of the distinct phase rotations may then be estimated. These estimates may be used to reconstruct an estimate of the swept-tone interferer, which may be subtracted from the composite signal to generate an interference-mitigated signal of interest.