Multi-Value Doppler Pre-Compensation for LEO Satellite Spot Beams
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Solution Overview
Problem
Conventional Doppler pre-compensation techniques in LEO satellite systems are inadequate for large spot beams, as they fail to sufficiently reduce Doppler shifts for UEs near the edge of the beam, leading to signal divergence and handling limitations.
Innovation Solution
A multi-value Doppler pre-compensation mechanism that considers spot beam/cell size and Doppler shift differences among UEs, allowing for different Doppler shift values to be applied to various parts of the spot beam/cell through synchronization signal blocks and control/data signals, enabling better signal alignment and access for UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-value Doppler pre-compensation is used, then the system is simple to implement, but UEs at the edge of large spot beams experience insufficient Doppler shift reduction leading to signal divergence
Solution Approach 1:
The patent divides the spot beam coverage area into multiple zones (center region and edge regions) and applies different Doppler pre-compensation values to each zone. This segmentation allows UEs at different positions to receive appropriate compensation, resolving the contradiction between maintaining simple implementation and improving signal handling for edge UEs.
Solution Approach 2:
The patent applies different Doppler pre-compensation values to different spatial locations within the spot beam. UEs in the center region receive one compensation value while UEs in edge regions receive different compensation values optimized for their specific positions, thereby improving overall signal handling capacity without excessive complexity.
2Reliability
If multi-value Doppler pre-compensation is implemented for different UE positions, then signal alignment improves for all UEs, but the signaling overhead and system complexity increase
Solution Approach 1:
The patent performs Doppler pre-compensation in advance before signal transmission, calculating and applying appropriate compensation values based on UE positions. This preliminary action ensures that signals are pre-adjusted to account for expected Doppler shifts, improving signal alignment while minimizing the need for complex real-time adjustments and reducing signaling overhead.
Solution Approach 2:
The patent changes the Doppler pre-compensation parameter values based on UE position within the spot beam. By adjusting these parameters according to location (center vs. edge), the system achieves better signal alignment for all UEs while managing signaling overhead through efficient parameter selection and transmission.
3Adaptability or versatility
If a single Doppler pre-compensation value is used for the entire spot beam, then the system complexity is low, but UEs at different radial positions experience different signal quality leading to access limitations
Solution Approach 1:
The patent segments the spot beam into multiple radial zones and assigns different Doppler pre-compensation values to each zone. This enables UEs at different radial positions (from center to periphery) to access the network effectively, improving overall system adaptability while maintaining manageable complexity through structured segmentation.
Solution Approach 2:
The patent creates a multi-functional Doppler pre-compensation system that can serve multiple UE positions simultaneously with different compensation values. This universal approach allows the system to adapt to various UE locations and conditions, enhancing access capability across the entire spot beam coverage area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances signal handling capacity by allowing UEs across the spot beam/cell to connect effectively, reducing frequency offsets and achieving robust communication, even at the edge of the beam, thereby improving system performance.
Implementation Method 1
Doppler pre-compensated control and data signal(s) generated using first and second Doppler pre-compensation patterns, respectively, are transmitted
Data Source
AI summary
Doppler pre-compensated control and data signal(s) generated using first and second Doppler pre-compensation patterns, respectively, are transmitted. A signal indicating the Doppler pre-compensation patterns is transmitted. The Doppler pre-compensated control signals comprise synchronization signals, system information blocks (SIBs), a radio resource control (RRC) message, or a physical downlink control channel (PDCCH), and the Doppler pre-compensated data signals comprise a physical downlink shared channel (PDSCH). The signal indicating the Doppler pre-compensation patterns comprises one of an RRC message or a PDCCH, and may indicate absolute Doppler values or a difference between Doppler values. The PDCCH may indicate a time offset between the PDCCH PDSCH.