Narrowband Interference Excision in Spread OFDM Systems
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Solution Overview
Problem
Existing wireless communication systems face interference issues from narrowband and wideband sources, including self-interference and intentional jamming, which affect system performance and reliability, and current methods are inadequate for robust interference mitigation.
Innovation Solution
A communications device and system that utilize a processor to receive and process spread OFDM signals, excising narrowband interference by distributing data across multiple subcarriers, and employing decision feedback equalization to recover data, while also equalizing and respreading the signals to improve link quality and reduce interference impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interference compensation methods (FEC, spread spectrum, diversity) are used, then some level of interference mitigation is achieved, but the system performance and reliability are still insufficient under strong narrowband interference conditions
Solution Approach 1:
The received OFDM signal is segmented into individual subcarriers in the frequency domain. Each subcarrier is processed independently to detect and excise narrowband interference, allowing targeted removal of interference affecting specific frequency components while preserving other subcarriers
Solution Approach 2:
Narrowband interference is extracted and removed from affected subcarriers through detection algorithms that identify interference patterns. The excised interference components are then replaced with estimated clean signal values, effectively taking out the harmful interference from the received signal
2Object-affected harmful factors
If frequency diversity is used to compensate for interference by adjusting operating frequency, then interference-free channels can be found, but the system complexity and channel switching overhead increase
Solution Approach 1:
Instead of switching frequencies to avoid interference, the patent processes multiple frequency subcarriers simultaneously within the same OFDM signal structure. This transforms the problem from a time-domain frequency switching approach to a parallel frequency-domain processing approach, maintaining system simplicity while achieving interference mitigation
3Object-affected harmful factors
If spatial diversity with multiple antennas is used to cancel interference, then interference rejection improves, but the device complexity and cost increase
Solution Approach 1:
The patent introduces signal processing algorithms as an intermediary between the received signal and the final decoded data. These processing steps (FFT transformation, subcarrier analysis, interference detection, excision, and IFFT reconstruction) act as a virtual intermediary that achieves interference rejection without requiring additional physical antenna elements
Data Source
AI summary
A communications device may include a wireless receiver, and a processor coupled to the wireless receiver. The processor may be configured to receive a spread OFDM signal having narrowband interference associated with the same, the spread OFDM signal having subcarriers with data distributed among the subcarriers. The processor may be configured to excise the narrowband interference from the spread OFDM signal, and despread the spread OFDM signal after excising and based upon the excising to recover the data.