UE DRX State Transition for Downlink Data Latency
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Solution Overview
Problem
In the RRC_INACTIVE state of wireless communication systems, the long Discontinuous Reception (DRX) periodicity delays downlink data transmission from the gNB to the UE, as the UE can only receive notifications at specific instances within a long DRX cycle, leading to delayed subsequent data transmission.
Innovation Solution
The UE listens for downlink data transmission in a specific period after transmitting uplink data and then enters a DRX state, allowing the gNB to transmit downlink data in a timely manner by configuring timers T1, T2, T3, and T4 for listening and DRX periods, which can be set via broadcast messages, dedicated signaling, or protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the UE uses a long DRX periodicity to save power in RRC_INACTIVE state, then power consumption is reduced, but downlink data transmission is delayed
Solution Approach 1:
The patent makes the DRX periodicity dynamic by introducing a first time window where the UE switches from long DRX periodicity to short DRX periodicity after uplink data transmission. This dynamic adjustment allows the UE to respond quickly to downlink data while still maintaining power savings during the majority of time in the long DRX cycle.
Solution Approach 2:
The patent prepares for potential downlink data transmission by establishing a first time window immediately after uplink data transmission. During this window, the UE uses short DRX periodicity to be ready to receive downlink data without delay, while the rest of the DRX cycle maintains long periodicity for power savings.
2Productivity
If the UE enters connected state to transmit large amount of data, then data transmission capability is improved, but power consumption and network resource usage increase
Solution Approach 1:
The patent segments the data transmission process by keeping the UE in RRC_INACTIVE state for the control plane connection while establishing a separate data radio bearer for user plane data transmission. This segmentation allows data transmission without full connection establishment, reducing power consumption and network resource usage.
Solution Approach 2:
The patent introduces an intermediary mechanism where the gNB can directly transmit downlink data to the UE in the short DRX window without requiring full RRC connection establishment. This intermediary approach enables data transmission while maintaining the UE in the lower-power RRC_INACTIVE state.
3Productivity
If the gNB transmits downlink data during long DRX cycle, then network resource utilization is improved, but data may be missed due to timing mismatch
Solution Approach 1:
The patent implements feedback mechanisms where the UE monitors for downlink data during the first time window using short DRX periodicity. The UE can provide feedback (ACK/NACK) for received downlink data, ensuring reliable transmission while maintaining efficient network resource utilization through the structured time window approach.
Data Source
AI summary
A data transmission method, device and system are provided. The method comprises: a UE in an RRC_INACTIVE state monitoring downlink data transmission within a determined time period after completing uplink data transmission; entering a DRX state after the determined time period has expired or downlink data has been completely received. The UE monitors the downlink data within the determined time period after completing the uplink data transmission, and enters the DRX state after the determined time period has expired or the downlink data has been completely received.