Signal Decision Apparatus Using Phase Difference Detection
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Solution Overview
Problem
Existing wireless LAN systems, particularly those compliant with the IEEE 802.11n standard, face challenges in quickly determining the type of received signal, which is essential for optimal gain adjustment and synchronization, as conventional methods require equalization and demapping processing that are not completed within a short period.
Innovation Solution
A signal decision apparatus and method that separates received signals into subcarriers, including pilot and data carriers, and uses phase difference information to determine the type of signal by detecting whether the phase difference between pilot and data carriers meets a predetermined condition, allowing for rapid type decision without the need for equalization and demapping processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional equalization and demapping processing is used to determine signal type, then measurement precision is improved, but processing time increases significantly
Solution Approach 1:
The patent extracts only the necessary phase difference information between pilot and data carriers from the received signal, separating this critical identification feature from the complete signal processing chain. By taking out only the phase difference component needed for signal type determination, the system achieves fast decision-making without performing the full equalization and demapping processing, thus resolving the contradiction between accuracy and time.
Solution Approach 2:
The patent segments the signal processing into two independent paths: one for rapid signal type identification using phase difference detection, and another for complete signal processing (equalization and demapping) that is performed only after type determination. This segmentation allows the system to prioritize speed for identification while maintaining completeness for processing, resolving the time-accuracy tradeoff.
2Loss of time
If rapid signal type decision is implemented, then processing time is reduced, but device complexity increases due to additional phase difference detection mechanisms
Solution Approach 1:
The patent makes the phase difference detection mechanism serve multiple functions: it not only identifies signal type but also provides phase information useful for subsequent equalization processing. By designing the detection unit to perform both identification and processing support functions, the system reduces overall device complexity despite adding rapid decision capability, as the same structural element serves multiple purposes.
Solution Approach 2:
The patent introduces phase difference information as an intermediary element that bridges the received signal and the decision-making process. Instead of directly analyzing the complete signal, the system uses phase difference as an intermediate representation that enables fast classification while requiring minimal additional processing complexity, thus resolving the contradiction between speed and complexity.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
An FFT unit (170) separates a received symbol by Fourier conversion into a plurality of subcarriers, and a phase difference detection unit (193) detects a phase difference between 4 pilot carriers and data carriers adjacent to the pilot carriers (adjacent carriers). The decision unit (194) decides whether the phase differences between the pilot carriers and the adjacent carriers detected by the phase difference detection unit (193) fulfill a phase difference condition. Then, the decision unit (194) decides that the received symbol is an HTSIG if the number of phase differences that fulfill the phase difference condition is greater than or equal to a predetermined number, and decides that the received symbol is either a SIG or a DATA if the number of phase differences that fulfill the phase difference condition is less than the predetermined number.