Adaptive Subframe Scheduling for Radar Detection in Unlicensed Spectrum
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Solution Overview
Problem
Current wireless communication networks face challenges in mitigating interference in unlicensed frequency bands, particularly when LTE devices operate near Wi-Fi devices, as conventional interference detection methods may lead to unnecessary back-off in transmission due to adjacent channel leakage or non-Wi-Fi interference.
Innovation Solution
The method involves adaptively using subframes, such as MBSFN subframes, to schedule traffic and radar detection in unlicensed spectrum, adjusting the number of subframes based on the type of primary user detected, allowing for efficient coexistence with radar systems and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional listen-before-talk (LBT) approach is used to detect interference in unlicensed band, then interference from Wi-Fi devices can be avoided, but unnecessary back-off occurs due to adjacent channel leakage or non-Wi-Fi interference
Solution Approach 1:
The patent applies local quality by performing different types of interference detection for different frequency locations. Specifically, it detects Wi-Fi interference in Wi-Fi bands and radar interference in radar bands separately, rather than using a uniform detection approach across all unlicensed bands. This allows the system to make targeted transmission decisions based on the specific interference conditions in each frequency region.
Solution Approach 2:
The patent changes the detection parameter from simple energy detection to type-specific detection. Instead of treating all detected energy as Wi-Fi interference, the system identifies whether the energy corresponds to Wi-Fi signals or radar signals, and adjusts transmission behavior accordingly. This parameter change eliminates unnecessary back-off caused by misidentifying radar signals as Wi-Fi interference.
2Reliability
If radar detection subframes are scheduled in unlicensed spectrum, then coexistence with radar systems is improved, but communication throughput may be reduced due to subframe allocation for detection
Solution Approach 1:
The patent applies dynamics by making the subframe configuration adaptive rather than static. The system dynamically adjusts the number and positioning of radar detection subframes based on actual radar presence and communication traffic conditions. When radar is detected, detection subframes are allocated; when no radar is present, more subframes are available for communication, thus optimizing throughput while ensuring radar coexistence.
Solution Approach 2:
The patent implements periodic radar detection through periodically scheduled detection subframes. Instead of continuous detection that would block all communication, the system uses periodic detection opportunities at specific subframe intervals. This allows communication to proceed in non-detection subframes while still maintaining radar awareness and compliance.
Data Source
AI summary
Systems and methods for adaptively using subframes for radar detection in unlicensed spectrum are disclosed. The systems and methods include scheduling a first set of subframes in a frame duration for traffic based at least in part on a first configuration for communications in an unlicensed frequency band. Further, the systems and methods include scheduling, based at least in part on the first configuration, a second set of subframes in the frame duration for detection of a primary user of the unlicensed frequency band. Moreover, the systems and methods include adjusting a number of subframes in the first and second set of subframes based on a second configuration for communications, wherein the second configuration for communications is identified based on a type of primary user being detected.