Cognitive Radio Frequency Band Detection via GPS Hashing
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Solution Overview
Problem
Current cognitive radio systems take too long to scan for unused frequency bands, especially in scenarios where frequency ranges are wide and conditions change rapidly, such as with a moving vehicle, necessitating quicker detection methods.
Innovation Solution
The use of a hash function that narrows down the detection range based on location and time information, obtained from GPS signals, allows radio communication apparatuses to quickly identify usable frequency bands by scanning a common frequency range when located and timed similarly, and different ranges when conditions change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the frequency band scanning range is widened to cover several MHz to several tens GHz, then the coverage of usable frequency bands is improved, but the scanning time increases to several tens of seconds
Solution Approach 1:
The patent divides the wide frequency band scanning task into two segments: a first coarse scanning that quickly identifies potential unused bands, and a second detailed scanning that verifies availability with high accuracy. This segmentation reduces the time required to cover wide frequency ranges by processing bands in stages rather than uniformly scanning all frequencies at high resolution.
Solution Approach 2:
The patent performs preliminary coarse scanning to identify candidate frequency bands before conducting detailed verification scanning. By pre-identifying potential unused bands through low-resolution initial scanning, the system avoids performing high-accuracy scanning across the entire wide frequency range, thereby reducing total scanning time while maintaining detection accuracy.
2Measurement precision
If the scanning accuracy is increased to reliably detect unused frequency bands, then the detection precision is improved, but the scanning time increases
Solution Approach 1:
The patent segments the detection process into two phases: first coarse scanning that quickly identifies candidate bands with lower accuracy requirements, and second detailed scanning that applies high-accuracy detection only to the narrowed-down candidate bands. This segmentation allows the system to achieve reliable detection precision while minimizing the time spent on scanning.
Solution Approach 2:
The patent applies high-accuracy scanning only partially, specifically only to the subset of frequency bands identified as candidates during the first coarse scanning phase. Rather than performing excessive high-accuracy scanning across all frequency bands, the system applies precise detection only where necessary, thereby maintaining detection reliability while reducing overall scanning time.
3Reliability
If the cognitive radio system performs comprehensive frequency band detection across all operable bands, then the reliability of frequency selection is improved, but the system cannot adapt quickly to rapidly changing conditions such as vehicle mobility
Solution Approach 1:
The patent segments the frequency detection process into rapid coarse scanning followed by targeted detailed scanning. This allows the system to quickly identify candidate frequency bands in changing environments while maintaining reliable frequency selection through subsequent verification scanning, thus balancing adaptation speed with selection reliability.
Solution Approach 2:
The patent performs preliminary coarse scanning to quickly identify candidate frequency bands before conditions change further. This preliminary action enables the system to rapidly adapt to changing environments such as vehicle mobility by pre-identifying potential usable bands, then verifies reliability through detailed scanning of only those candidates.
Data Source
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AI summary
Provided is a technique that enables quicker detection of usable frequency bands in a cognitive radio system. Each radio communication apparatus in the system has, in common, a hash function used to obtain a frequency range from time information and location information. Each radio communication apparatus detects unused frequency bands while narrowing down a frequency range over which a detection process is performed by obtaining the terminal's own location information and current time information from GPS signals, and input them to the hash function. Since a transmitting node and a receiving node that perform a communication are at locations close to each other at the same time, they perform detection in the same frequency range. Therefore, an unused frequency band(s) that is usable by both of them can be detected. Furthermore, at different locations or at different times, the detection will be performed in different frequency ranges. Therefore efficient frequency utilization can be achieved. It is preferred that the nodes have a plurality of kinds of hash functions in common.