RRC Inactive UE Scheduling via PDCCH Monitoring
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Solution Overview
Problem
In 5G NR networks, UEs in the RRC_INACTIVE state experience unnecessary power consumption and signaling overhead due to frequent transitions to RRC_CONNECTED state for small and infrequent data transmissions, which undermines the latency and efficiency benefits of the INACTIVE state.
Innovation Solution
A UE apparatus is configured to monitor a physical downlink control channel (PDCCH) for UE-specific scheduling during an active period after an initial data transmission, allowing subsequent data transmissions without transitioning to RRC_CONNECTED state, using configurations received in RRC release messages or System Information Blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for data transmission, then reliable data transmission is ensured, but power consumption increases and transmission latency increases due to state transition overhead
Solution Approach 1:
The network performs preliminary actions by paging the UE in advance before actual data transmission. The UE transitions to CONNECTED state only when paging is received, allowing the network to control timing and reduce unnecessary state transitions. This preliminary paging action ensures reliability while minimizing power consumption by avoiding premature state transitions.
Solution Approach 2:
The UE alternates between RRC_INACTIVE and RRC_CONNECTED states in periodic cycles. During INACTIVE state, the UE conserves power by not maintaining full connectivity. When data needs to be transmitted, the UE periodically transitions to CONNECTED state, performs transmission, then returns to INACTIVE state. This periodic action pattern reduces average power consumption while ensuring data transmission reliability when needed.
2Productivity
If the UE transitions to RRC_CONNECTED state for data transmission, then data can be transmitted, but signaling overhead increases due to frequent state transitions
Solution Approach 1:
The invention extracts the essential data transmission function from the full RRC_CONNECTED state by enabling small data transmission while the UE remains in RRC_INACTIVE state. Only the necessary signaling for small data transmission is performed, while the complex state transition and full connection setup signaling is eliminated. This extraction reduces signaling overhead while maintaining data transmission capability.
Solution Approach 2:
The network performs preliminary configuration and resource allocation actions while the UE is still in INACTIVE state, so that when data transmission is needed, the UE can immediately transmit without undergoing full state transition procedures. This preliminary action reduces the signaling overhead associated with state transitions by pre-establishing necessary parameters and resources.
3Loss of time
If the UE monitors PDCCH for subsequent data transmission, then transmission latency is reduced, but power consumption increases due to continuous monitoring
Solution Approach 1:
The UE monitors PDCCH periodically rather than continuously while in RRC_INACTIVE state. The monitoring occurs at specific intervals or triggered by specific events (such as receiving paging or reaching certain time points), rather than maintaining continuous monitoring. This periodic monitoring reduces power consumption compared to continuous monitoring while still enabling relatively fast response to data transmission opportunities, thus reducing latency compared to full state transitions.
Data Source
AI summary
A user equipment (UE) may perform operations, including receiving a Radio Resource Control (RRC) release message from a base station, where the RRC release message comprises a suspend configuration to transition the UE to an RRC_INACTIVE state. In addition, the operations include entering the RRC_INACTIVE state. The operations include performing, while the UE is in the RRC_INACTIVE state, an initial data transmission without transitioning from the RRC_INACTIVE state to an RRC_CONNECTED state. Additionally, the operations include monitoring a physical downlink control channel (PDCCH) for a UE dedicated scheduling for a transmission or reception of a subsequent data during an active period, while the UE is in the RRC INACTIVE state. Further, the operations include performing the transmission or reception of the subsequent data based on the monitoring of the PDCCH.