PRACH RO Group Selection for Beam-Aligned Random Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The overlapping of new and legacy PRACH resources in the time domain leads to invalid ROs, reducing the actual PRACH transmission number and impairing coverage performance due to the network device's inability to receive and detect preambles from directions not aligned with its generated beams.
Innovation Solution
A method for a terminal device to select and transmit preambles using RO groups where the union set of SSB indexes is within a defined threshold, ensuring all ROs in the group can transmit preambles, and a network device to determine valid RO groups based on transmission number, proportion, or quantity criteria to enhance coverage and reduce PRACH transmission delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If new PRACH resources are added to enhance coverage capability, then coverage capability is improved, but resource conflict occurs with legacy PRACH resources causing invalid ROs
Solution Approach 1:
The patent segments the PRACH resources by introducing RO groups with specific SSB index associations. Each RO group is configured to be associated with a specific SSB index, creating distinct resource segments that avoid conflicts between new and legacy PRACH resources. This segmentation allows the network to selectively activate appropriate RO groups based on SSB configurations, ensuring that only valid, non-conflicting resources are used for preamble transmission.
Solution Approach 2:
The patent applies local quality by configuring different RO groups with different SSB index associations in different time-frequency locations. Instead of uniformly applying PRACH resources across all locations, the network configures specific RO groups to be associated with specific SSB indexes, creating locally optimized resource allocations that avoid conflicts while maximizing coverage in specific directions.
2Productivity
If multiple SSBs are mapped to overlapping PRACH resources, then resource utilization increases, but beam direction conflict occurs reducing detection capability
Solution Approach 1:
The patent segments the mapping relationship between SSBs and PRACH resources by introducing RO groups with explicit SSB index associations. Each RO group is configured to be associated with a specific SSB index, creating distinct mapping segments that prevent beam direction conflicts. This ensures that each PRACH resource is clearly associated with a specific beam direction, eliminating ambiguity in preamble detection.
Solution Approach 2:
The patent introduces RO groups as an intermediary layer between SSBs and PRACH resources. The RO group configuration acts as a mediator that establishes clear, unambiguous mappings between SSB indexes and PRACH resources. This intermediary structure resolves the conflict by providing a structured association mechanism that prevents beam direction conflicts while maintaining efficient resource utilization.
3Measurement precision
If RO groups are configured with SSB index associations, then beam alignment accuracy improves, but configuration complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring RO groups with specific SSB index associations during network setup. The gNB configures the RO group information in advance, establishing the mapping relationships between SSB indexes and PRACH resources before actual random access occurs. This preliminary configuration eliminates the need for complex real-time beam alignment decisions, simplifying the terminal's operation while maintaining high precision.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A communication method and apparatus are provided, to enhance a coverage capability of a PRACH and improve random access performance. A terminal device receives first information from a network device, where the first information indicates a time-frequency position of a first PRACH resource, the first PRACH resource includes at least one RO group, and the terminal device determines one RO group in the at least one RO group to transmit a preamble with repetitions. Any RO in the at least one RO group is an RO that is capable of being used to transmit a preamble, a quantity of SSB indexes included in a union set of a first index set corresponding to the at least one RO group and a second index set corresponding to a first RO is less than or equal to a first threshold, the first index set is an SSB index associated with an RO that is at a first time domain position and that is in the at least one RO group, the second index set is an SSB index associated with the first RO at the first time domain position, and the first RO is an RO used to transmit a preamble without repetitions.