Frequency Hopping Bandwidth Switching Under Broadband Interference
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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 coexistence issues between wideband and narrowband systems, particularly when wideband systems cover the entire frequency range used by narrowband systems like Bluetooth.
Innovation Solution
A method and apparatus for transmitting a frequency hopping signal that employs a dual interference detect and avoid (DAA) scheme, where interference is detected on a subset of frequency channels, marking them as unusable for a longer period, and switching to a smaller bandwidth without DAA for coexistence, allowing proactive puncturing of frequency ranges to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wideband system uses LBT to detect and avoid narrowband FH transmissions, then interference to narrowband systems is reduced, but the wideband system cannot utilize the full bandwidth effectively and data rates are limited
Solution Approach 1:
The wideband channel is segmented into multiple sub-channels or frequency regions. The system performs LBT independently on each sub-channel rather than on the entire wideband channel. This allows the wideband system to transmit on sub-channels that are idle while avoiding sub-channels occupied by narrowband FH transmissions, thereby maintaining high data rates while reducing interference to narrowband systems.
Solution Approach 2:
Different parts of the wideband spectrum are treated differently based on local interference conditions. Each sub-channel is assessed individually for narrowband activity, and transmission decisions are made locally for each sub-channel. This enables the wideband system to maintain high utilization of bandwidth by transmitting on interference-free sub-channels while protecting narrowband systems on occupied sub-channels.
2Adaptability or versatility
If a narrowband FH system uses DAA to avoid wideband LBT transmissions, then coexistence with wideband systems is improved, but the narrowband system cannot find sufficient free channels when wideband systems occupy most of the spectrum
Solution Approach 1:
The narrowband FH system dynamically adapts its frequency hopping pattern based on detected wideband activity. When wideband LBT transmissions are detected, the system dynamically adjusts its hopping sequence to avoid those frequencies. This dynamic adaptation allows the narrowband system to maintain transmission success by continuously adjusting to the presence of wideband systems while still achieving good coexistence.
3Object-affected harmful factors
If LBT is used for spectrum sharing, then wideband transmissions can detect and avoid narrowband transmissions, but narrowband FH transmissions are not reliably detected by wideband systems due to low average power
Solution Approach 1:
The wideband system performs periodic LBT measurements on sub-channels at regular intervals. This periodic sampling increases the probability of detecting narrowband FH transmissions by capturing their activity during the measurement windows. The periodic nature of LBT allows the wideband system to build a more reliable picture of narrowband presence over time, improving detection reliability despite the intermittent and low-power nature of narrowband transmissions.
Data Source
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AI summary
Methods and apparatus are provided. In an example aspect, a method of transmitting a signal is provided. The method comprises 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.