OFDM Signal Correlation for RAN Availability Detection
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Solution Overview
Problem
Communication terminals face challenges in accurately determining the availability of communication systems while minimizing energy consumption, as existing methods are either inaccurate due to power level variations from fading and shadowing or inefficient due to high processing loads and battery consumption.
Innovation Solution
A determination apparatus for Orthogonal Frequency Division Multiplexing (OFDM) communication systems that includes a reception unit, an obtaining unit, a correlation value calculation unit, and a determination unit to assess communication availability by calculating the correlation value of discrete sample signals at predefined time shifts, allowing for accurate determination without relying solely on power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power level detection method is used to find available RAN, then terminal can easily find a RAN, but determination accuracy deteriorates because power level varies according to fading and shadowing
Solution Approach 1:
The patent changes the detection parameter from power level to autocorrelation value. By calculating the autocorrelation value of received signals and comparing it with a threshold, the system can accurately determine RAN availability without being affected by fading and shadowing that cause power level variations.
2Measurement precision
If base station transmits notification information about congestion situation, then terminal can accurately determine non-congested RAN, but energy consumption increases due to access, synchronization, and demodulation requirements
Solution Approach 1:
The patent extracts only the necessary information (RAN availability) from the complex notification mechanism. By using autocorrelation-based detection, the terminal can determine RAN availability without accessing the base station, synchronizing clocks, or demodulating notification information, thereby significantly reducing energy consumption.
Solution Approach 2:
The terminal performs self-detection of RAN availability using autocorrelation calculation on received signals. This self-service approach eliminates the need for energy-consuming interactions with the base station (access, synchronization, demodulation) while maintaining accurate determination capability.
3Measurement precision
If FFT is applied to received wireless signals to directly determine data traffic, then data traffic can be directly determined, but processing load becomes extremely heavy
Solution Approach 1:
The patent replaces the computationally expensive FFT process with a simpler autocorrelation calculation. The autocorrelation method achieves direct determination of data traffic with significantly lower processing load, making it suitable for resource-constrained terminals.
4Measurement precision
If base station transmits congestion information in notification information, then terminal can accurately determine RAN availability, but standard specifications need to be changed which reduces ease of realization
Solution Approach 1:
The terminal independently determines RAN availability by calculating autocorrelation values of received signals. This approach does not require any changes to base station transmission protocols or notification information structures, thereby maintaining compatibility with existing standards and improving ease of realization.
Data Source
AI summary
A determination apparatus for determining communication availability in an Orthogonal Frequency Division Multiplexing (OFDM) scheme communication system, the determination apparatus includes a reception unit configured to receive a wireless signal including an OFDM symbol in which a pilot signal is inserted at a constant interval in a frequency axis direction, an obtaining unit configured to obtain a discrete sample signal by sampling the wireless signal, a correlation value calculation unit configured to calculate a correlation value of the discrete sample signal for a time shift amount that is defined in advance according to the constant interval, and a determination unit configured to determine the communication availability in the communication system based on at least a result of determination whether the correlation value for the time shift amount has a peak or not.