Radio Receiver Signal Detection Using Autocorrelation
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Solution Overview
Problem
Radio communication devices face a trade-off between power consumption and speed of network access, as frequent attempts to connect to a network consume energy but infrequent attempts lead to delayed access when coverage becomes available, posing the 'container problem'.
Innovation Solution
A low-power trigger mechanism using autocorrelation to detect radio signals with duplicated parts, such as OFDM signals, reduces the frequency of full network access attempts, allowing for frequent low-power detection and rapid signal acquisition by comparing the similarity of signal parts, thereby minimizing power consumption and maximizing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If full network access attempts are performed frequently, then speed of signal acquisition is improved, but power consumption increases
Solution Approach 1:
The network access process is divided into two distinct stages: (1) a low-power initial detection stage using autocorrelation to detect the presence of a radio signal, and (2) a full network access stage performed only when a signal is detected. This segmentation allows the device to spend most time in the low-power state while maintaining the ability to quickly access the network when needed.
Solution Approach 2:
The patent performs preliminary signal detection using autocorrelation before initiating full network access attempts. This preliminary action identifies the presence of a radio signal in advance, allowing the device to avoid performing computationally expensive full access attempts when no signal is present, thereby reducing overall power consumption while maintaining fast acquisition when signals are available.
2Use of energy by moving object
If full network access attempts are performed infrequently, then power consumption is reduced, but speed of signal acquisition deteriorates
Solution Approach 1:
The patent introduces an intermediary detection mechanism (autocorrelation-based signal presence detection) that acts as a gateway between the low-power state and full network access. This intermediary performs minimal processing to detect signal presence, enabling the system to maintain low power consumption while being prepared to quickly transition to full access mode when a signal is detected, thus resolving the speed-power tradeoff.
3Measurement precision
If complex correlation techniques are used for network access, then detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The detection process is segmented into two complexity levels: (1) a simple autocorrelation-based presence detection that requires minimal computation, and (2) the more complex full network access correlation techniques that are only performed when needed. This segmentation maintains high detection accuracy when signals are present while minimizing computational complexity during the majority of time when no signal is detected.
Solution Approach 2:
The patent applies partial action by performing only the minimal necessary detection (autocorrelation) to determine signal presence, rather than performing the full complex correlation analysis continuously. The complete analysis is performed only partially, and only when the simple detection indicates a signal is present, thus reducing overall computational complexity while maintaining detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables both low power consumption and fast network signal acquisition, overcoming the 'container problem' by allowing frequent low-power detection without sacrificing speed, and only initiating full network access when a signal is detected, thus reducing computational and battery power usage.
Implementation Method 1
a first part of a sequence of samples of the radio signal is obtained. A second part of the sequence of samples of the radio signal is obtained. The similarity of the first part of the sequence with the second part of the sequence is computed
Data Source
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AI summary
A radio receiver (120) is provided for low-power detection of a radio signal (130), wherein said receiver (120) is configured to receive a radio signal (130) over a radio network (100); convert at least part of the received radio signal into a sequence of samples; compare the similarity of a first part (210), (310), (310') of the sequence and a second part (230), (330) of the sequence, wherein the first part and the second part are of equal length; and in response to said similarity being greater than a similarity threshold: detect a phase difference between the first part of the sequence and the second part of the sequence; calculate a frequency offset between a frequency of the received radio signal and an expected frequency of the received radio signal using said phase difference (518); and use said calculated frequency offset to attempt (508) full access to the radio network.