Configured Grant Small Data Transmission in RRC Inactive State
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Solution Overview
Problem
Current wireless communication systems, particularly in the 5G NR, face inefficiencies in Configured Grant-based Small Data Transmission (CG-SDT) due to unnecessary power consumption and signaling overhead when handling small data packets in the RRC_INACTIVE state, leading to increased performance and battery drain issues as the number of UEs increases.
Innovation Solution
Implementing a method for User Equipment (UE) to perform Configured Grant-based Small Data Transmission (CG-SDT) by initiating transmissions through a first configured Uplink (UL) grant with Hybrid Automatic Repeat Request (HARQ) and retransmitting if feedback is not received, utilizing Common Control Channel (CCCH) messages and Physical Downlink Control Channel (PDCCH) for feedback, and managing timers to optimize data transmission without transitioning to the RRC_CONNECTED state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for small data transmission, then reliable data transmission is achieved, but power consumption and signaling overhead increase
Solution Approach 1:
The patent segments the data transmission process into two parts: small data packets are transmitted using pre-configured grants in RRC_INACTIVE state (low power mode), while larger or more complex transmissions can transition to RRC_CONNECTED state (full functionality mode). This segmentation allows the system to use the most energy-efficient method for simple cases while preserving full capability when needed.
Solution Approach 2:
The network pre-configures uplink grants and transmission parameters for the UE while it is in RRC_INACTIVE state. These preliminary configurations include configured grants, power control parameters, and transmission settings that enable the UE to immediately transmit small data packets without transitioning to connected state, thus avoiding the power consumption and signaling overhead of state transition.
2Adaptability or versatility
If the UE transitions to RRC_CONNECTED state for small data transmission, then full network functionality is available, but signaling overhead increases
Solution Approach 1:
The patent segments transmission scenarios into small data packets (handled in RRC_INACTIVE with pre-configured grants) and larger/complex transmissions (handled in RRC_CONNECTED). This segmentation reduces signaling overhead by avoiding unnecessary state transitions for simple cases while preserving full network functionality for complex scenarios.
Solution Approach 2:
The network provides copies of transmission configurations (configured grants, power control parameters, transmission settings) to the UE in advance while it is in RRC_INACTIVE state. These configuration copies enable the UE to autonomously transmit small data packets without requiring real-time network control, thus reducing signaling overhead.
3Use of energy by moving object
If the UE uses configured grants for small data transmission, then power consumption is reduced, but HARQ feedback reliability becomes critical
Solution Approach 1:
The patent implements HARQ feedback mechanisms where the network monitors uplink transmissions using configured grants and sends acknowledgments to the UE. This feedback ensures that even though the UE operates autonomously in RRC_INACTIVE state with reduced power consumption, the reliability of data transmission is maintained through proper acknowledgment and retransmission protocols.
Data Source
AI summary
A method and a user equipment (UE) for performing a Configured Grant-based Small Data Transmission (CG-SDT) is provided. The method includes performing an initial transmission of the CG-SDT via a first configured Uplink (UL) grant associated with a Hybrid Automatic Repeat Request (HARQ) process; determining whether a feedback from the BS has been received for the first configured UL grant associated with the HARQ process; and performing a retransmission for the initial transmission of the CG-SDT via a second configured UL grant if the feedback has not been received.