Preamble Generating Device for Arbitrary Length OFDM Signals
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Solution Overview
Problem
Existing preamble generation technologies for OFDM schemes face challenges in reducing the peak-to-average power ratio (PAPR) of preambles, especially when the preamble length is arbitrary, and are limited in generating preambles of varying lengths and types.
Innovation Solution
A preamble generating device that determines a preamble model, reorders and transforms data sequences using FFT and IFFT operations to achieve a low PAPR, with cyclic shifting and threshold-based processing to adjust the PAPR and autocorrelation, allowing for the generation of preambles of arbitrary lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the preamble length is increased to improve detection accuracy, then the PAPR increases causing more distortion
Solution Approach 1:
The patent changes the parameter of preamble length from fixed to arbitrary/variable lengths. By allowing the preamble length to be dynamically adjusted based on detection requirements, the system can achieve low PAPR for short preambles while maintaining sufficient detection accuracy when longer preambles are needed, thus resolving the contradiction between detection accuracy and PAPR distortion
Solution Approach 2:
The patent introduces dynamic preamble length adjustment capability. Instead of using a fixed preamble length, the system can adaptively select appropriate lengths based on the specific detection task requirements, enabling flexible optimization between PAPR performance and detection accuracy for different应用场景
2Object-generated harmful factors
If the preamble length is fixed to a specific value, then the PAPR can be controlled, but the flexibility to generate preambles of arbitrary lengths is lost
Solution Approach 1:
The patent creates a universal preamble generation method that can handle preambles of any length. The technique uses FFT-based processing and cyclic shifting operations that work effectively for arbitrary preamble lengths, making the system multi-functional and adaptable to different requirements without needing separate solutions for different preamble lengths
3Ease of manufacture
If the preamble is generated using conventional methods, then the generation process is simple, but the resistance to distortion is insufficient
Solution Approach 1:
The patent incorporates feedback mechanisms through iterative cyclic shifting operations and threshold-based adjustments. The system evaluates the generated preamble's PAPR and autocorrelation properties, and uses this feedback to adjust the cyclic shift amount and other parameters, thereby improving distortion resistance while maintaining relatively simple generation process
Solution Approach 2:
The patent employs periodic cyclic shifting operations to generate the preamble. By applying cyclic shifts in periodic intervals and adjusting the shift amounts based on predetermined patterns, the system achieves low PAPR and good autocorrelation properties, improving distortion resistance through a systematic periodic process
Data Source
AI summary
A first calculator generates first computational data by multiplying each element in a result obtained by applying a fast Fourier transform to data containing at least one of a real data sequence and an imaginary data sequence with reordered elements by an element of a preamble model at a same position as the each element. A second calculator generates second computational data by performing computation that converts an absolute value of each element in the inverse fast Fourier-transformed first computational data into a value in a predetermined range. A third calculator generates third computational data by multiplying each element in the fast Fourier-transformed second computational data by an element of the preamble model at a same position as the each element. A decider generates the third computational data as a preamble in a case of the PAPR of the inverse fast Fourier-transformed third computational data matching a predetermined criterion.