CG PUSCH SSB Mapping for RRC_INACTIVE Small Data
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Solution Overview
Problem
Current wireless communication systems, particularly in the 5G NR, face inefficiencies in transmitting Configured Grant (CG) Physical Uplink Shared Channel (PUSCH) due to unnecessary power consumption and signaling overhead, especially in the RRC_INACTIVE state where intermittent small data packets require frequent connection resumptions.
Innovation Solution
The solution involves configuring the UE to perform Small Data Transmission (SDT) in the RRC_INACTIVE state by providing a Configured Grant (CG) configuration, allowing for efficient mapping of SSB indexes to PUSCH resources, optimizing the association period, and validating PUSCH occasions to reduce unnecessary transmissions and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE frequently transitions to RRC_CONNECTED state for small data transmission, then the data transmission reliability is improved, but the power consumption and signaling overhead increase
Solution Approach 1:
The network pre-configures uplink resources (CG PUSCH) and transmission parameters for the UE while it remains in RRC_INACTIVE state. This preliminary configuration allows the UE to transmit small data packets immediately without transitioning to CONNECTED state, thereby reducing power consumption while maintaining transmission reliability through pre-validated resource allocations.
Solution Approach 2:
The system dynamically selects between RRC_INACTIVE and RRC_CONNECTED states based on data transmission requirements. For small periodic data packets, the UE remains in INACTIVE state using pre-configured resources. For larger or unpredictable data, the UE transitions to CONNECTED state. This dynamic state management optimizes the trade-off between power consumption and transmission reliability.
2Reliability
If the UE frequently transitions to RRC_CONNECTED state for small data transmission, then the data transmission reliability is improved, but the signaling overhead increases
Solution Approach 1:
The network performs preliminary configuration of uplink resources, transmission parameters, and resource mappings while the UE is in RRC_INACTIVE state. This advance configuration eliminates the need for extensive signaling during actual data transmission, as the UE can directly use the pre-configured resources without additional connection setup procedures.
Solution Approach 2:
The invention extracts the essential resource configuration and transmission parameters from the normal RRC connection setup procedure and provides them in advance through dedicated configuration messages. This separation allows the UE to transmit small data packets without undergoing the complete connection establishment process, thereby reducing signaling overhead while maintaining transmission reliability.
3Productivity
If multiple SSB indexes are mapped to the same PUSCH resource, then the resource utilization is improved, but the resource collision and interference increase
Solution Approach 1:
The system applies different mapping strategies to different SSB indexes based on local conditions. SSB indexes corresponding to UEs with similar channel conditions and spatial directions are mapped to the same PUSCH resource, while SSB indexes with different spatial characteristics are mapped to different resources. This localized quality differentiation reduces resource collisions and interference while maintaining high resource utilization.
Solution Approach 2:
The mapping relationship between SSB indexes and PUSCH resources is dynamically adjusted based on channel conditions, spatial parameters, and interference levels. By changing the mapping parameters adaptively, the system optimizes resource utilization while minimizing resource collisions and interference between different UEs transmitting on the same physical resources.
Data Source
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AI summary
A method and a UE for transmitting a CG PUSCH is provided. The method includes receiving a CG configuration and a plurality of SSBs, each SSB corresponding to an SSB index in a plurality of SSB indexes; determining a mapping of the plurality of SSB indexes to PUSCH resources for the plurality of SSBs, each PUSCH resource being configured by the received CG configuration; identifying an SSB in the plurality of SSBs based on measured RSRPs; identifying a PUSCH resource in the PUSCH resources based on the identified SSB and the mapping of the plurality of SSB indexes to the PUSCH resources; and transmitting a PUSCH on the identified PUSCH resource, wherein the mapping of the SSB indexes to the PUSCH resources is configured in a first increasing order of DMRS resource indexes and in a second increasing order of CG period indexes within an association period.