Frequency-Hopping Transmission With Bandwidth Switching for Coexistence
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Solution Overview
Problem
Existing spectrum sharing mechanisms, such as Listen Before Talk (LBT) and Frequency Hopping (FH), are ineffective when different communication technologies use different methods, leading to interference and reduced effectiveness in coexistence, particularly when wideband systems interfere with narrowband systems using adaptive frequency hopping (AFH).
Innovation Solution
A method and apparatus for transmitting a frequency hopping signal that employs an interference detect and avoid (DAA) scheme on a first plurality of frequency channels, and switches to a second bandwidth without DAA when interference is detected in a predetermined proportion of the first channels, using proactive puncturing to avoid interference and ensure coexistence with narrowband systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wideband system uses LBT to detect and defer from transmitting when a narrowband FH transmission is detected, then interference to the narrowband system is avoided, but the wideband system cannot utilize the channel even when the narrowband transmission is not actively interfering
Solution Approach 1:
The wideband channel is segmented into multiple sub-channels or frequency portions. The system performs LBT detection on specific sub-channels rather than the entire wideband channel, allowing selective transmission on portions of the spectrum that are not currently occupied by narrowband transmissions.
Solution Approach 2:
Different parts of the wideband channel are treated differently based on local interference conditions. The system identifies specific frequency regions where narrowband transmissions are occurring and avoids only those local regions, while allowing transmission in other regions of the same wideband channel.
2Productivity
If a wideband system does not detect a narrowband system due to low average power, then the wideband system can initiate transmission, but this results in harmful interference to the narrowband system
Solution Approach 1:
The wideband system performs preliminary detection scans across the frequency spectrum before initiating transmission. This preliminary action allows the system to identify narrowband transmissions even when their average power is low, by scanning for their presence across different frequency portions before committing to transmission.
Solution Approach 2:
The system implements feedback mechanisms where transmission outcomes are monitored and used to adjust detection sensitivity. When interference issues are detected, the system adjusts its detection parameters to become more sensitive to narrowband transmissions in future channel access decisions.
3Object-affected harmful factors
If AFH is used to avoid interfered frequency channels, then coexistence with wideband systems is improved, but it takes significant time to determine whether a channel should be avoided
Solution Approach 1:
Instead of performing exhaustive detection across all frequency channels, the system performs partial detection on a selected subset of channels or uses excessive detection on only the most critical frequency regions. This reduces the time required for channel assessment while still providing effective interference avoidance.
Solution Approach 2:
The system performs preliminary channel assessments using simplified criteria before full AFH detection. This preliminary action quickly identifies obviously interfered channels, allowing the system to avoid spending time on channels that are clearly unsuitable, thereby reducing overall assessment time.
4Productivity
If all frequency channels are used by a wideband system, then maximum bandwidth utilization is achieved, but AFH becomes ineffective as no free channels remain for narrowband systems
Solution Approach 1:
The wideband system segments its transmission across multiple frequency channels rather than occupying all channels continuously. This segmentation creates temporal and spectral opportunities for narrowband systems to operate, allowing AFH to remain effective while maintaining high overall bandwidth utilization.
Solution Approach 2:
The wideband system employs periodic transmission patterns with intentional gaps or silent periods on certain channels. This periodic action creates windows of opportunity for narrowband systems to transmit, ensuring that AFH can identify and utilize available channels while the wideband system maintains high productivity during its active transmission periods.
Data Source
AI summary
Methods and apparatus are provided. In an example aspect, a method of transmitting a signal is provided. The method includes transmitting a frequency hopping signal on a first plurality of frequency channels in a first bandwidth using a first interference detect and avoid (DAA) scheme for each of the plurality of frequency channels, detecting interference in a predetermined proportion of the first plurality of frequency channels, and transmitting the frequency hopping signal on a second plurality of frequency channels in a second bandwidth smaller than the first bandwidth without using the first interference DAA scheme in response to detecting interference in the predetermined proportion of the first plurality of frequency channels.