Wireless Signal Acquisition Using Subcode FFT Segmentation
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Solution Overview
Problem
Existing wireless communication systems face high computational complexity and memory usage when calculating Fast Fourier Transforms (FFTs) for signal acquisition, particularly as the size of the acquisition sequence increases, leading to resource-intensive processing and potential slowdowns due to external memory usage.
Innovation Solution
The approach involves dividing a large acquisition code symbol sequence into smaller subcodes, each with substantially the same transmissive energy, allowing for reduced computational operations and memory usage by performing FFT calculations on these subcodes, which reduces the overall processing complexity and memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FFT is used to calculate correlation in frequency domain, then computational efficiency is improved, but hardware resources and memory usage increase significantly as acquisition sequence size increases
Solution Approach 1:
The patent divides the large acquisition sequence into multiple smaller sub-sequences. Instead of performing a single large FFT operation on the entire acquisition sequence, the system performs multiple smaller FFT operations on segmented portions. This segmentation reduces the computational complexity and memory requirements of each individual FFT operation while maintaining the overall correlation detection capability through subsequent combination of results.
2Reliability
If acquisition sequence size increases, then processing gain is improved, but memory usage and computational complexity increase
Solution Approach 1:
The patent segments the large acquisition sequence into smaller sub-sequences that can be processed with reduced memory requirements. By dividing the sequence, the system maintains the processing gain benefits of longer sequences while avoiding the exponential memory growth that would otherwise be required to store and process the entire sequence in a single FFT operation.
Solution Approach 2:
The patent performs preliminary processing by computing FFT of individual sub-sequences before combining them. This preliminary action allows the system to prepare smaller data sets that require less memory, and then combine these pre-processed results to achieve the equivalent of a full-length sequence processing gain without the corresponding memory burden.
3Measurement precision
If acquisition sequence size increases, then correlation peak detection accuracy is improved, but processing time increases due to external memory usage
Solution Approach 1:
By segmenting the acquisition sequence into smaller sub-sequences, the patent enables processing to be completed using internal memory rather than requiring external memory access. This segmentation allows multiple smaller FFT operations to be performed faster in sequence, reducing the overall processing time while maintaining correlation peak detection accuracy through proper combination of the segmented results.
Data Source
AI summary
In an embodiment, a receiver includes an antenna configured to receive a communication frame. The communication frame may include an acquisition code symbol sequence, which in turn may include a plurality of acquisition code symbols. In an embodiment, an acquisition code symbol includes a subcode sequence having a plurality of subcodes. A receiver also may include a correlation calculator coupled to the antenna. The correlation calculator may be configured to determine a correlation between the subcodes of the received communication frame and a stored version of the subcodes. The correlation may be used in determining a timing offset for further processing of the communication frame.