Bidirectional-Spiral Channel Search for Cognitive Radio
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Solution Overview
Problem
Conventional unidirectional channel scanning methods in cognitive radio networks may miss available free channels, leading to inefficient identification of the nearest free channel for transmission, especially in dynamically varying spectra, and do not ensure minimal radio parameter changes during reconfiguration.
Innovation Solution
A bidirectional-spiral searching algorithm that scans the spectrum in both directions from a starting frequency, expanding progressively and switching to unidirectional or random searches upon encountering boundaries, ensuring identification of the nearest free channel with minimal radio parameter changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unidirectional channel scanning is used, then the scanning process is simple and fast, but available free channels may be missed and the nearest free channel cannot be ensured
Solution Approach 1:
The scanning process is segmented into bidirectional phases: an initial unidirectional scan in the first frequency direction, followed by a reverse unidirectional scan in the opposite frequency direction. This segmentation allows comprehensive coverage of the frequency spectrum while maintaining manageable complexity in each individual scanning phase.
Solution Approach 2:
The patent applies inversion by performing the second scan in the opposite frequency direction to the first scan. After scanning from lower to higher frequencies (or vice versa) in the first phase, the system reverses the scanning direction to ensure that free channels missed in the first direction are detected in the second direction, thereby improving reliability.
2Reliability
If bidirectional scanning is performed to find the nearest free channel, then channel identification accuracy improves, but the scanning time and complexity increase
Solution Approach 1:
The patent performs preliminary unidirectional scanning in both frequency directions before conducting a comprehensive bidirectional search. By预先 scanning in simplified unidirectional modes, the system identifies candidate free channels and establishes frequency boundaries, which reduces the search space for the subsequent bidirectional nearest-channel detection, thereby reducing overall scanning time.
Solution Approach 2:
The scanning algorithm applies different scanning strategies to different frequency regions. In regions where free channels are likely to be found during preliminary scans, the system focuses the bidirectional search locally around those frequencies rather than uniformly scanning the entire spectrum, thus reducing total scanning time while maintaining accuracy.
Data Source
AI summary
A method of identifying an available channel of a plurality of frequency channels defined in a radio frequency spectrum for use by a transmitting station, wherein scanning for an available channel in a frequency spectrum is performed by a scanning method in which a bidirectional search is performed away from an initial channel frequency. The method may include steps to take when a boundary of the spectrum is encountered, and may also take into account existing information concerning channel reservation. A related scanner and radio apparatus is also described.