NTN Beam Sweeping Using Dual Broadcast Signals for Faster Access
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Solution Overview
Problem
The current NR beam sweeping solution in NTN systems is inefficient, leading to prolonged satellite access times, especially for UEs at edge beam positions, where the UE may miss the satellite due to long search times, making it difficult to capture and access satellites as the number of beams increases.
Innovation Solution
Implementing a method where UEs receive a first broadcast signal with reduced periodicity and narrower bandwidth to quickly determine the strongest receive beam direction, followed by accessing the satellite using a second broadcast signal, with non-overlapping frequency spectra and sparser frequency rasters to accelerate satellite access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE uses the current NR beam sweeping solution with default 20ms SSB periodicity to search for satellites, then the UE can complete frequency sweeping and beam alignment, but the satellite access time becomes excessively long (52.28s for single frequency, proportional to quantity of to-be-swept frequencies for multiple frequencies)
Solution Approach 1:
The patent segments the traditional single broadcast signal into two distinct broadcast signals: a first broadcast signal with reduced periodicity for rapid beam direction identification, and a second broadcast signal with standard periodicity for subsequent access procedures. This segmentation allows the UE to quickly determine the strongest receive beam direction using the first signal without compromising the accuracy of beam alignment, while significantly reducing the overall satellite access time.
Solution Approach 2:
The patent implements preliminary action by having the UE receive and process the first broadcast signal before the second broadcast signal. The first broadcast signal is used to pre-identify the strongest receive beam direction, which serves as a preliminary step that guides subsequent reception of the second broadcast signal. This preliminary beam direction identification reduces the time required for complete satellite acquisition while maintaining alignment accuracy.
2Area of stationary object
If the UE increases the number of beams to improve coverage, then the beam coverage area increases, but the time required for frequency sweeping and beam alignment increases proportionally, making it increasingly difficult to capture and access satellites
Solution Approach 1:
The patent divides the beam sweeping process into two phases using two different broadcast signals. The first broadcast signal enables rapid identification of the strongest receive beam direction across multiple beams, while the second broadcast signal handles detailed access procedures. This segmentation allows the system to maintain comprehensive beam coverage without proportionally increasing the time required for satellite capture.
Solution Approach 2:
The patent changes the periodicity parameter of the first broadcast signal to be shorter than the minimum periodicity of the second broadcast signal. This parameter change allows the UE to quickly traverse all receive beam directions and identify the optimal beam direction within a reduced time frame, even when dealing with a large number of beams, thereby maintaining coverage while reducing capture time.
3Reliability
If the UE performs beam alignment on a satellite at a moment, then the UE can establish communication with that satellite, but the satellite may have flown away and cannot cover the UE by the time the UE completes the alignment process
Solution Approach 1:
The patent uses the first broadcast signal to perform preliminary identification of the strongest receive beam direction before the satellite moves significantly. This preliminary action ensures that the UE has already identified the correct beam direction while the satellite is still within the coverage area, thereby maintaining access reliability even as the satellite moves. The shortened periodicity of the first signal enables this preliminary identification to occur faster than the satellite's movement rate.
Solution Approach 2:
The patent introduces dynamic behavior by using two broadcast signals with different periodicities. The first broadcast signal dynamically adapts to the satellite's movement by providing updated beam direction information at a faster rate, allowing the UE to track and maintain alignment with the moving satellite more effectively than a single static-periodicity signal could provide.
Data Source
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AI summary
Embodiments of this application provide a non-terrestrial network NTN access method and a communication apparatus. The method includes: A terminal device receives at least one first broadcast signal based on a first periodicity or continuously receives the at least one first broadcast signal, to obtain a target first broadcast signal, where the first periodicity is less than a minimum sending periodicity of a second broadcast signal; receives at least one second broadcast signal based on the target first broadcast signal, to obtain a target second broadcast signal; and performs access based on the target second broadcast signal. When a sending periodicity of the first broadcast signal is reduced, efficiency of traversing all receive beam directions by the UE is higher, so that a strongest receive beam direction can be determined more quickly, to improve satellite access efficiency.