RAR Scramble Value Determination for Random Access Ambiguity
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Solution Overview
Problem
In contention-based random access procedures, terminals face ambiguity in detecting Random Access Responses (RARs) due to large subcarrier spacing, leading to incorrect identification of RACH resources, which affects RAR detection accuracy.
Innovation Solution
The method involves determining a scramble value for RARs based on the time unit, frequency domain resource, and maximum RAR time window length, ensuring accurate identification of RACH resources by using specific formulas to calculate the RA-RNTI, allowing terminals to distinguish between different preambles and corresponding RACH resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the terminal sends preambles at multiple configured RACH time-frequency resource locations within the same subframe, then the random access capability is enhanced, but the RAR detection accuracy deteriorates due to ambiguity in distinguishing RACH resources
Solution Approach 1:
The patent segments the RACH resource identification by introducing time unit index (i) and frequency domain resource index (f_id) as separate identifying components. Instead of relying solely on subframe number, the system divides the time domain into multiple time units and assigns unique indices to each time unit and frequency resource, enabling precise segmentation and identification of RACH resources even when multiple preambles are sent within the same subframe.
Solution Approach 2:
The patent adds new dimensions to the RA-RNTI calculation by incorporating the time unit index (i) and frequency domain resource index (f_id) as additional parameters. The RA-RNTI is calculated using the formula: RA-RNTI = 1 + i + Nframe × f_id, where i represents the time unit index and f_id represents the frequency domain resource index. This dimensional expansion allows unique identification of RACH resources across multiple time units and frequency resources within the same subframe.
2Productivity
If the subcarrier spacing is increased to 60 kHz, then the spectral efficiency is improved, but the RAR detection accuracy deteriorates due to multiple RACH resources at the same frequency domain location
Solution Approach 1:
The patent segments the time domain into multiple time units (each containing multiple slots) and assigns unique time unit indices (i) to each time unit. When multiple RACH resources are present at the same frequency domain location due to large subcarrier spacing, the system distinguishes them by their time unit indices, ensuring accurate RAR detection while maintaining the spectral efficiency benefits of 60 kHz subcarrier spacing.
Solution Approach 2:
The patent introduces the time unit index (i) as an additional dimension to the resource identification system. The RA-RNTI calculation incorporates this time unit index along with the frequency domain resource index (f_id), creating a multi-dimensional identification space that resolves the ambiguity caused by multiple RACH resources at the same frequency location in high subcarrier spacing configurations.
3Device complexity
If the RA-RNTI is determined using only absolute time index, then the calculation complexity is reduced, but the RAR detection accuracy deteriorates due to inability to distinguish RACH resources
Solution Approach 1:
The patent segments the time domain into multiple time units and assigns unique indices (i) to each time unit. The RA-RNTI calculation incorporates this time unit index along with the frequency domain resource index (f_id), creating a multi-dimensional identification space that resolves the ambiguity caused by multiple RACH resources at the same frequency location in high subcarrier spacing configurations.
Solution Approach 2:
The patent introduces the time unit index (i) as an additional dimension to the resource identification system. The RA-RNTI calculation incorporates this time unit index along with the frequency domain resource index (f_id), creating a multi-dimensional identification space that resolves the ambiguity caused by multiple RACH resources at the same frequency location in high subcarrier spacing configurations.
Data Source
AI summary
This application provides a communication method and a communications device. The method includes: after a terminal sends a first preamble to a network device, determining, by both the terminal and the network device, a scramble value of a first RAR according to an ith time unit, a first frequency domain resource, and a maximum RAR time window length, where the ith time unit is a first time unit corresponding to a first time domain resource, the maximum time window length includes M time units, and M equals to an integer multiple of a quantity of time units included in a system frame of each system parameter in a plurality of system parameters for communication between the terminal and the network device. Therefore, RAR detection accuracy may be improved.