SSB Grouping for Random Access Resource Efficiency in Unlicensed Spectrum
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Solution Overview
Problem
In New Radio (NR) communications, especially in unlicensed spectrums, channel detection failures lead to wasted resources as base stations cannot transmit Synchronization Signal Blocks (SSBs) planned for transmission, resulting in inefficient utilization of Random Access (RA) resources.
Innovation Solution
Grouping multiple SSBs and selecting a primary SSB from each group, with the base station sending indication information to User Equipment (UE) and transmitting at most one SSB per group, along with the number of SSBs corresponding to preambles and Random Access Channel Occasions (ROs) under Frequency Division Multiplexing (FDM), allowing the UE to determine the corresponding preamble and RO for RA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station performs channel detection before transmitting each SSB in unlicensed spectrum, then the transmission reliability of SSB is improved, but the resource utilization rate of RA resources deteriorates due to wasted RO resources when channel detection fails
Solution Approach 1:
The patent segments the N SSBs into multiple groups, where each group contains one or more SSBs. The base station performs channel detection before each group and transmits at most one SSB per group. This segmentation allows the system to limit the waste of RA resources to only the groups affected by channel detection failures, rather than wasting resources for all N SSBs, thus resolving the contradiction between transmission reliability and resource utilization.
2Ease of operation
If the base station allocates RO and preamble for all N planned SSBs, then the UE can determine corresponding RA resources for each SSB, but the resource allocation efficiency deteriorates when some SSBs cannot be transmitted due to channel detection failure
Solution Approach 1:
The patent segments the N SSBs into multiple groups and informs the UE of the grouping structure. The base station allocates RO and preamble resources for each group rather than for every individual SSB. When channel detection fails for a group, the allocated RA resources for that group are not wasted. This segmentation approach maintains ease of operation for the UE while significantly improving resource allocation efficiency.
Solution Approach 2:
The patent applies partial action by allocating RA resources only for groups that successfully pass channel detection, rather than allocating resources for all N planned SSBs in advance. The base station transmits at most one SSB per group and allocates corresponding RA resources dynamically, avoiding the excessive allocation of resources for SSBs that will not be transmitted due to channel detection failures.
3Area of stationary object
If all N SSBs are transmitted in unlicensed spectrum, then the downlink coverage is improved, but the RA resource utilization rate deteriorates due to channel detection failures
Solution Approach 1:
The patent segments the N SSBs into multiple groups, allowing the system to maintain downlink coverage by transmitting multiple SSBs across different groups while limiting RA resource waste to only those groups affected by channel detection failures. Each group can be independently transmitted based on channel conditions, optimizing both coverage and resource utilization.
Solution Approach 2:
The patent introduces dynamic transmission where the base station transmits at most one SSB per group based on real-time channel detection results. The transmission of SSBs becomes dynamic and adaptive to channel conditions, rather than transmitting all N SSBs statically. This dynamic approach improves RA resource utilization while maintaining downlink coverage through flexible transmission decisions.
Data Source
AI summary
Provided are a Random Access (RA) configuration method and apparatus, an RA method and apparatus, a base station, User Equipment (UE) and a computer-readable storage medium. The RA configuration method may include: grouping multiple Synchronization Signal Blocks (SSBs) and selecting a primary SSB from each SSB group; sending UE indication information indicating a primary SSB to be sent in an SSB group to be sent; sending at most one SSB in each SSB group to be sent to the UE; and sending the number of SSBs corresponding to preambles in each RA Channel (RACH) Occasion (RO) and the number of ROs under Frequency Division Multiplexing (FDM) to the UE.