Preconfigured Uplink Resource Access for Idle UE Data Transmission
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in uplink data transmission for user equipment (UE) in radio resource control (RRC) idle or inactive modes, leading to significant signaling overhead and power consumption due to the need for establishing an RRC connection for each data transmission.
Innovation Solution
The implementation of preconfigured uplink resources (PURs) and uplink signals, allowing UE in RRC idle or inactive modes to transmit data without full connection setup, using acknowledgement messages to confirm data reception, thereby reducing the need for additional signaling steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If UE in RRC idle or inactive mode transmits uplink data through traditional methods, then data transmission can be achieved, but signaling overhead and power consumption increase due to requiring full RRC connection establishment
Solution Approach 1:
The network pre-configures uplink resources (PUR) and associated parameters for UE before the UE enters RRC idle or inactive mode. This preliminary configuration includes PUR resource allocation, timing advance (TA) values, and other transmission parameters, allowing UE to immediately transmit data without performing full connection establishment procedures when data needs to be sent.
Solution Approach 2:
The uplink transmission process is segmented into two parts: (1) transmission of uplink signals (such as SRS or dedicated reference signals) while in idle/inactive mode to provide channel information, and (2) subsequent data transmission on pre-configured resources. This segmentation allows the UE to maintain a lightweight connection state while still enabling efficient data transmission.
2Reliability
If UE establishes full RRC connection for each data transmission, then reliable data transmission is ensured, but signaling overhead increases
Solution Approach 1:
Instead of performing complete RRC connection establishment procedures, the UE performs only partial actions necessary for data transmission in idle/inactive mode. The network provides sufficient configuration information in advance (PUR resources, TA values, etc.) so that UE can transmit data with minimal signaling, performing full connection establishment only when absolutely necessary.
Solution Approach 2:
The network creates a simplified copy of the connection state by pre-configuring essential transmission parameters and resources before the UE enters idle/inactive mode. This configuration copy includes PUR resource allocations, timing advance values, and other necessary parameters, allowing the UE to replicate transmission behavior without maintaining the full original connection state.
3Measurement precision
If UE transmits uplink signals periodically while in idle mode, then channel estimation accuracy improves, but power consumption increases
Solution Approach 1:
The UE transmits uplink signals such as sounding reference signals (SRS) or dedicated reference signals periodically or aperiodically while in RRC idle or inactive mode. These periodic transmissions provide the network with channel estimation information and timing advance updates without requiring full connection establishment, balancing measurement accuracy with energy efficiency.
Data Source
AI summary
A UE in one of an RRC idle mode or an RRC inactive mode may transmit a plurality of UL reference signals to the base station, receive a first L1 ACK message based on the transmission of the plurality of UL signals from the base station, and transmit UL data via at least one PUR based on the received first L1 ACK message. The plurality of UL signals may include SRS. The UE may receive a PUR configuration from the base station. The UE may determine to drop the transmission of one or more first UL signals, or the base station may determine to omit the transmission of the first L1 ACK message in response to one or more first UL signals, based on L1 ACK density or L1 ACK message in the L1 ACK monitoring window.