Frequency-Hopping Scheme With Minimum Separation
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Solution Overview
Problem
Wireless devices communicating on a particular center frequency often experience channel degradation or interference, and simply hopping to neighboring frequencies does not effectively mitigate these issues due to coherence bandwidth, which affects both the current and neighboring frequencies.
Innovation Solution
A frequency-hopping scheme that ensures a minimum separation between consecutive hops, using a method to generate a random number and select a target center frequency that is at least this minimum separation away from the previous frequency, ensuring each frequency has an equal chance of being selected, thereby avoiding undesirable channel deterioration and improving coexistence with non-frequency-hopping devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless devices hop to neighboring frequencies to avoid channel degradation, then frequency diversity is improved, but the coherence bandwidth effect causes neighboring frequencies to also suffer from degradation
Solution Approach 1:
The patent changes the frequency hopping parameter from hopping to adjacent frequencies (distance of 1 channel) to hopping to frequencies separated by at least a minimum separation (distance of N channels). This parameter change ensures that the frequency hop distance exceeds the coherence bandwidth, thereby avoiding the harmful effect where neighboring frequencies share the same degradation characteristics.
2Reliability
If frequency hopping is implemented to avoid interference, then communication reliability is improved, but device complexity increases due to the need for frequency management logic
Solution Approach 1:
The patent implements self-service frequency hopping where each device independently generates its own frequency sequence using a random number generator and the same hopping algorithm. This eliminates the need for complex centralized frequency management logic or coordination protocols, as devices automatically select frequencies that satisfy the minimum separation requirement without requiring extensive control logic.
3Reliability
If frequency hopping is used to mitigate interference, then signal quality is improved, but interference from non-frequency-hopping devices increases due to frequency concentration
Solution Approach 1:
The patent segments the frequency spectrum into multiple channels and uses random number generation to distribute frequency hops uniformly across all available channels. This segmentation approach ensures that frequency-hopping devices are dispersed across the entire frequency spectrum rather than concentrating on a subset of frequencies, thereby reducing interference from non-frequency-hopping devices that operate on fixed frequencies.
4Reliability
If minimum separation between frequency hops is enforced, then coherence bandwidth effects are avoided, but the number of valid frequency choices is reduced
Solution Approach 1:
The patent uses feedback from the random number generator to dynamically select valid frequency hops. The random number generator produces a random index that is used to select the next frequency from a predefined list of valid frequencies that satisfy the minimum separation requirement. This feedback mechanism ensures that only valid frequency transitions are executed, maintaining both coherence bandwidth compliance and frequency selection flexibility.
Data Source
AI summary
A method comprises generating, by logic, a random number. The method also comprises determining a next frequency in said sequence using the random number and one or more of a minimum separation, a channel number, and a number of channels. The method further comprises hopping to the next frequency.