Random Access Sequence Generation for High Doppler Shift
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Solution Overview
Problem
Existing random access sequence generation methods in communications technologies face interference issues due to insufficient range for shift sequence number selection when Doppler frequency shift exceeds physical random access channel subcarrier spacing, leading to inefficient sequence generation.
Innovation Solution
A method and system for generating random access sequences by instructing user equipment to select shift sequence numbers from a broader range, using specific formulas to calculate cyclic shift values, ensuring adequate sequence generation and detection, even at higher Doppler frequency shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the range for shift sequence number selection is limited to avoid interference when Doppler frequency shift exceeds PRACH subcarrier spacing, then interference between random access sequences is reduced, but the range for shift sequence number selection becomes excessively small
Solution Approach 1:
The patent extends the selection range from the traditional limited interval to a broader range spanning from 0 to ceiling(L/N_CS)-1, where L is the sequence length and N_CS is the cyclic shift spacing. This dimensional expansion in the shift sequence number space allows more candidate sequences while maintaining interference avoidance through proper cyclic shift allocation within this expanded range.
Solution Approach 2:
The patent changes the parameter definition of the selection range from a restricted interval to a systematic range defined by ceiling(L/N_CS). This parameter transformation enables the system to accommodate high-speed mobile scenarios by providing adequate candidate sequences while maintaining the mathematical relationship that ensures orthogonal or near-orthogonal sequences for different users.
2Object-affected harmful factors
If a targeted design with three parameters (quantity of groups, quantity of UE candidate sequence shifts in a group, quantity of UE candidate sequence shifts in the last length) is used to avoid interference, then random access sequence interference is reduced, but the selection range becomes excessively small and limits adaptability
Solution Approach 1:
The patent creates a universal selection range formula ceiling(L/N_CS) that works across different Doppler frequency shift scenarios, including high-speed mobile cases. This single unified range definition replaces the complex three-parameter targeted design, providing both interference avoidance and broad adaptability to various communication scenarios without requiring scenario-specific parameter adjustments.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the selection range to automatically adjust based on the relationship between sequence length L and cyclic shift spacing N_CS. This dynamic range definition enables the system to adapt to different Doppler frequency shifts and mobility scenarios without manual reconfiguration, while the base station dynamically assigns cyclic shifts within this adaptive range to avoid interference.
Data Source
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AI summary
Embodiments of the present invention provide a random access sequence generation method, a device, and a system. The random access sequence generation method includes: generating, by a base station, notification signaling, where the notification signaling includes indication information, the indication information is used to instruct user equipment UE to select a shift sequence number from a range of 0 to the shift sequence number is an integer, is a quantity of UE candidate sequence shifts in a group, is a quantity of groups, is a quantity of UE candidate sequence shifts in the last length that is insufficient for a group, is a quantity of UE candidate sequence shifts in first remaining sequence shifts, and is a quantity of UE candidate sequence shifts in second remaining sequence shifts; and sending, by the base station, the notification signaling to the UE, so that the UE generates a random access sequence according to the indication information.