Cognitive Radio Signal Detection Using Correlation Matrix
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Solution Overview
Problem
Cognitive radio (CR) secondary communication apparatuses face inefficiencies in sensing primary system signals, leading to potential collisions and resource wastage, particularly in multiple input multiple output orthogonal frequency division multiplexing (MIMO OFDM) environments, as existing methods do not adequately address the need for precise and efficient signal detection without separate sensing time periods.
Innovation Solution
The CR communication apparatus employs a correlation matrix-based method to sense primary user signals using elements associated with known signals from secondary transmitters, allowing for precise and efficient detection without dedicated sensing time, reducing false alarm and missed detection probabilities by controlling the size and form of the correlation matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the secondary communication apparatus periodically stops communication operations to sense a signal of a primary system, then the detection accuracy of primary system signals is improved, but radio resources such as time resources are wasted
Solution Approach 1:
The patent merges the data reception function with the signal sensing function by processing received data signals through correlation matrix operations to detect primary system signals. This eliminates the need for separate sensing time periods, as the sensing is performed concurrently with normal data reception using the received signal energy itself.
Solution Approach 2:
The patent enables continuous sensing of primary system signals during ongoing data reception operations. The correlation matrix computation is performed continuously on incoming signals without interrupting communication operations, maintaining continuous useful action for both data transmission and interference detection.
2Reliability
If the secondary communication apparatus uses traditional sensing methods to detect primary system signals, then the presence of signals can be determined, but false alarm probability and missed detection probability cannot be sufficiently reduced
Solution Approach 1:
The patent replaces traditional energy-based detection methods with correlation matrix-based signal processing. By computing the correlation matrix of received signals and analyzing its eigenvalues or diagonal elements, the system can distinguish between primary system signals and noise/interference more effectively, reducing both false alarms and missed detections.
Solution Approach 2:
The patent changes the detection parameter from simple signal energy or power measurement to correlation matrix properties (eigenvalues, diagonal elements). This parameter transformation enables more precise characterization of signal structure and improves detection reliability by exploiting the statistical properties of the correlation matrix under different signal conditions.
3Measurement precision
If the secondary communication apparatus performs signal sensing in MIMO OFDM environments, then comprehensive signal detection can be achieved, but computational complexity increases
Solution Approach 1:
The patent extracts only the essential information from the full MIMO OFDM signal processing by focusing computation on the correlation matrix of received signals. Rather than performing complete MIMO channel estimation and equalization, the method extracts sufficient statistics through correlation matrix computation, reducing computational burden while maintaining detection capability.
Solution Approach 2:
The patent applies partial action by performing correlation matrix computation on a subset of received signals or using simplified correlation calculations. The method uses only the necessary computational steps required for detection purposes, avoiding excessive processing of all signal parameters, thereby reducing complexity while achieving adequate detection performance.
Data Source
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AI summary
A cognitive radio (CR) communication apparatus and method is provided. A cognitive radio (CR) communication apparatus includes a signal receiving unit which receives signals from a primary user of a primary system and a secondary transmitter of a secondary system, the received signals including an element associated with at least one known signal of the secondary transmitter, and a determination unit which determines whether a signal of the primary user exists from among the received signals based on the element associated with the at least one known signal.