Adaptive Filter Tap Order Selection for Interference Suppression
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Solution Overview
Problem
Modern communication systems face challenges in effectively reducing narrowband interference due to intentional or unintentional jamming and multipath distortion, especially in wideband radio channels, which can cause bit errors and disrupt signal reception.
Innovation Solution
An adaptive filter system with a variable delay circuit and tap order selection mechanism, using weighted coefficients and algorithms like LMS, RLS, or MMSE, to dynamically adjust filter taps and gain based on measured output power and demodulator state, allowing for improved multipath performance and interference suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the number of adaptive filter taps is increased to handle multiple interferers, then interference suppression capability is improved, but device complexity and platform resource usage increase
Solution Approach 1:
The patent implements dynamic tap order selection where the adaptive filter adjusts its tap order based on detected interference conditions. The filter can switch between different tap orders (e.g., order 2, order 4, order 6) depending on the number and strength of interferers present, allowing the system to optimize performance while managing computational resources efficiently
Solution Approach 2:
The system changes the parameter of filter tap order dynamically based on interference detection. By monitoring the signal environment and adjusting the tap order parameter accordingly, the system adapts to handle varying numbers of interferers without maintaining maximum complexity continuously
2Object-affected harmful factors
If the adaptive filter updates coefficients rapidly to track changing interferers, then interference suppression effectiveness is improved, but computational load and power consumption increase
Solution Approach 1:
The adaptive filter applies periodic updates to its coefficients rather than continuous updates. The system updates filter coefficients at specific intervals or under certain conditions (e.g., when interference characteristics change significantly), reducing computational load while maintaining effective tracking of interferers
Solution Approach 2:
The filter maintains continuous interference suppression capability through sustained adaptive operation, but the update rate is modulated based on conditions. The useful action of interference cancellation continues continuously, while the computationally intensive coefficient updates occur only when necessary
3Object-affected harmful factors
If adaptive filter processing is applied to the entire waveform including preamble, then interference reduction is improved, but waveform synchronization and parameter detection accuracy deteriorate
Solution Approach 1:
The patent segments the waveform processing into distinct portions: the preamble is processed separately from the data portion. The adaptive filter is applied selectively - either bypassing the preamble or applying it with different parameters - to preserve synchronization accuracy while still providing interference reduction for the data portion
Solution Approach 2:
The system performs preliminary processing of the preamble portion before applying adaptive filtering to the data portion. By handling synchronization and parameter detection first (during preamble), then applying interference reduction (during data portion), the system avoids degrading synchronization accuracy while still achieving interference suppression
4Adaptability or versatility
If the adaptive filter uses more filter taps to handle multiple interferers, then the number of handleable interferers increases, but platform constraints such as FPGA usage and power are exceeded
Solution Approach 1:
The system dynamically adjusts the tap order based on the detected number of interferers. When few interferers are present, a lower tap order is used to conserve resources. When multiple interferers are detected, the system increases the tap order to handle them effectively, optimizing the balance between capability and resource usage
Solution Approach 2:
The tap order parameter is changed dynamically to match the interference environment. The system can switch between different tap order configurations (e.g., 2, 4, 6 taps) to adapt to varying numbers of interferers, providing versatility without permanently committing to high resource usage
Data Source
AI summary
A communications system receives a modulated signal that carries encoded communications data. An adaptive filter has a plurality of non-adaptive and adaptive filter taps with weighted coefficients and a tap order selection circuit for selecting the number and order of adaptive filter taps based on one of at least measured output power from the adaptive filter and signal modulation. A demodulator and decoder receives the filtered output signal and demodulates and decodes the signal to obtain the communications data.