DSSS Signal Receiver Using Rotated Trial Sequences for Fast Detection
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Solution Overview
Problem
Detecting direct sequence spread spectrum (DSSS) signals in a short time interval is challenging due to the need for precise alignment of the spreading code with the received chip sequence, which can span multiple symbols, hindering efficient antenna diversity and signal decoding.
Innovation Solution
A receiving device and method that utilize a correlation unit to compare the latest chip sequence with rotated trial chip sequences, allowing for detection of a symbol within a shorter time frame by identifying correlation values exceeding a threshold, and adjusting antenna selection and power modes based on detection success, thereby reducing detection time and minimizing false detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the spreading code is aligned with the received chip sequence for accurate decoding, then the decoding accuracy is improved, but the detection time increases because the chip sequence may span multiple symbols
Solution Approach 1:
The patent applies preliminary action by pre-generating all possible trial chip sequences (all combinations of M bits encoded with the spreading code) before receiving the actual signal. When a chip sequence is received, the system immediately compares it against the pre-generated trial sequences to identify matches, eliminating the need for time-consuming real-time alignment calculations and enabling rapid detection without sacrificing decoding accuracy
Solution Approach 2:
The system dynamically adapts its detection approach by using correlation-based matching between received chip sequences and trial sequences. Instead of requiring fixed alignment, the system can identify signals even when they span symbol boundaries by finding the best match among trial sequences, allowing flexible handling of variable timing conditions while maintaining detection accuracy
2Reliability
If the chip sequence is processed to accommodate multiple symbols, then the signal detection reliability is improved, but the complexity of synchronization increases
Solution Approach 1:
The patent segments the complex synchronization problem into manageable parts by dividing it into: (1) receiving a chip sequence of N chips, (2) comparing against pre-generated trial sequences that represent all possible M-bit symbol combinations, and (3) identifying matches through correlation. This segmentation transforms a complex alignment problem into a series of simpler comparison operations, reducing synchronization complexity while maintaining reliable detection across multiple symbols
3Reliability
If antenna diversity is implemented for improved signal reception, then the reception reliability is improved, but the detection time increases due to the need to evaluate multiple antennas
Solution Approach 1:
The patent applies partial action by implementing a two-stage antenna diversity approach: first performing rapid correlation-based detection to identify potential signal presence and basic quality metrics, then performing more comprehensive evaluation only on antennas that pass the initial screening. This allows the system to quickly eliminate poor antennas without fully evaluating all possibilities, reducing antenna selection time while maintaining reception reliability
Data Source
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AI summary
A direct-sequence spread spectrum (DSSS) signal receiving device (10) is described. The device (10) may comprise a receiver unit (22), a chip sequence generating unit (44), a correlation unit (28), and comparison unit (38). The receiver unit (22) may extract, in a detection phase, a chip stream from a radio-frequency signal, said chip stream containing a first chip sequence. The chip sequence generating unit (44) may generate, in said detection phase, a plurality of trial chip sequences on the basis of a first trial chip sequence and on the basis of a plurality of index rotations, each trial chip sequence being index-rotated relative to said first trial chip sequence by one of said index rotations. The correlation unit (28) may determine, in said detection phase, a plurality of correlation values on the basis of said plurality of trial chip sequences and on the basis of said first chip sequence, each of said correlation values indicating a degree of correlation between a respective one of said trial chip sequences and said first chip sequence. The comparison unit (38) may determine, in said detection phase, whether a maximum one of said correlation values exceeds a defined threshold value. A method is also described.