Blind OFDM Preamble Detection via Autoconvolution
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Solution Overview
Problem
Traditional OFDM receiver techniques for preamble detection in complex valued sample streams are computationally challenging due to the need to process a large number of possible patterns, making them unsuitable for environments with many possible patterns.
Innovation Solution
The method involves autoconvolving a portion of the OFDM complex valued sample stream to detect peaks, selecting the peak with the greatest energy, and using autocorrelation to determine the timing and identify the preamble, thereby eliminating the need to process multiple patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If supervised techniques are used for preamble detection in OFDM receivers, then detection accuracy can be maintained for known patterns, but computational complexity increases significantly when dealing with a large number of possible patterns
Solution Approach 1:
The patent extracts the essential characteristic of preamble detection by removing the requirement for prior knowledge of sample stream patterns. Instead of processing multiple known patterns, the system extracts and processes only the autoconvolved signal to detect preambles blindly, significantly reducing computational complexity while maintaining detection capability
Solution Approach 2:
The patent introduces autoconvolution as an intermediary processing step between the raw OFDM sample stream and preamble detection. This intermediary transformation converts the complex pattern-matching problem into a simpler peak-detection problem in the autoconvolved signal domain, resolving the contradiction between accuracy and complexity
2Productivity
If blind preamble detection is implemented to reduce computational complexity, then processing speed improves, but detection reliability may deteriorate without knowledge of sample stream patterns
Solution Approach 1:
The patent replaces the mechanical pattern-matching approach with a mathematical transformation approach using autoconvolution. This substitution enables blind detection by transforming the signal into a domain where preambles manifest as distinct peaks, maintaining reliability without requiring prior pattern knowledge
Solution Approach 2:
The patent changes the parameter domain by applying autoconvolution transformation to the OFDM sample stream. This parameter transformation converts the detection problem from the time-domain signal amplitude space to the autoconvolved signal space, where preamble detection becomes more reliable through peak identification
Data Source
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AI summary
A method for determining a presence of a preamble for an orthogonal frequency division multiplexed (OFDM) complex valued sample stream may include capturing a portion of the OFDM complex valued (20) stream and autoconvolving the portion of the OFDM complex valued sample stream to generate an autconvolved portion (22). The method may further include determining a presence of a preamble in the OFDM complex valued sample stream if a peak is detected in the autoconvolved portion (24).