Air-to-ground interference avoidance via single grant and victim carrier detection
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Solution Overview
Problem
Existing air-to-ground communication systems face challenges in efficiently managing interference across multiple channels, particularly when operating as secondary users in shared frequency bands, which can lead to reduced flexibility and increased interference with primary users.
Innovation Solution
The implementation of a single grant scheme across multiple air-to-ground communication channels, combined with an adaptive system for detecting and reacting to changing channel conditions, allows for efficient interference avoidance and spectrum utilization. This system includes methods for interference detection at both the aircraft and ground stations, using techniques such as power measurement, block error rate monitoring, and acknowledgment channel analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single grant scheme is used across multiple air-to-ground communication channels, then control channel signaling is reduced and system simplicity is improved, but flexibility in managing diverse channel conditions deteriorates
Solution Approach 1:
The patent segments the control channel signaling into two parts: a single grant for resource allocation across multiple carriers, and separate interference detection mechanisms (victim carrier detection, block error rate monitoring) that operate independently on each carrier. This segmentation reduces overall signaling overhead while maintaining the ability to adapt to channel-specific conditions through distributed detection and selective carrier removal.
Solution Approach 2:
The patent implements feedback loops where the aircraft station detects interference on individual carriers and reports victim carriers back to the ground station. The ground station then removes affected carriers from the carrier aggregation configuration. This feedback mechanism enables the system to adapt to changing channel conditions without requiring complex centralized control signaling for each carrier.
2Productivity
If multiple carriers are scheduled with a single grant, then scheduling efficiency is improved, but interference detection and victim carrier removal complexity increases
Solution Approach 1:
The patent enables the air-to-ground communication system to self-detect and self-correct interference issues through autonomous victim carrier detection at the aircraft station and automatic carrier removal at the ground station. The system uses inherent signals (block error rates, acknowledgments) to detect interference without requiring additional complex detection infrastructure, and automatically adjusts the carrier aggregation configuration to maintain scheduling efficiency.
3Productivity
If air-to-ground systems operate as secondary users in shared frequency bands, then spectrum utilization is improved, but interference with primary users increases
Solution Approach 1:
The patent converts the harmful effect of shared spectrum usage into a benefit by implementing victim carrier detection that identifies and removes carriers experiencing primary user interference. The system uses the presence of interference as a signal to trigger carrier removal, thereby transforming the potential harm of spectrum sharing into an opportunity for adaptive resource management that protects primary users while maintaining secondary user connectivity on unaffected carriers.
4Productivity
If LTE specification is directly applied to ATG systems, then communication efficiency is improved, but control channel robustness requirements increase which cannot always be guaranteed
Solution Approach 1:
The patent adopts a simplified control channel approach where the single grant scheme serves as a lightweight, disposable control mechanism that allocates resources across multiple carriers without requiring the robust, persistent control channels of full LTE specification. The system accepts that individual control signals may be lost or interfere with primary users, but compensates through efficient single-grant allocation and automatic carrier removal, achieving LTE-level efficiency with reduced control channel overhead and reliability requirements.
Data Source
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AI summary
Techniques to reduce scheduling grants to minimize or eliminate the use of control channels, at the expense of flexibility, allow protection of the system from unnecessary retransmissions in case of interference from the primary system. Use of a single grant to allocate a set of resources across all carriers, or communication channels simplifies the system at the cost of retransmission of a grant for all carriers in the case if interference corrupts the transmission of a subset of the carriers. Thus, complementing a single grant embodiment with detection of the affected frequency carriers or victim carriers and remove such carriers from the carrier aggregation configuration allows more efficient use of the allocated spectrum.