RRC-Inactive Uplink Transmission via Pre-Configured Grants for Small Data
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Solution Overview
Problem
Existing wireless communication systems in the RRC_INACTIVE state of 5G NR lack an efficient mechanism for initial uplink data transmission, leading to increased latency and signaling overhead due to the need for state transitions to RRC_CONNECTED state for small data transmissions.
Innovation Solution
Implementing pre-configured grant (pre-CG) configurations for user equipment (UE) in the RRC_INACTIVE state, which includes conditions such as access type, transmission priority, and valid timing advance, allowing initial data transmission without transitioning to RRC_CONNECTED state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for initial uplink data transmission in inactive state, then the data transmission can be performed, but the transmission latency increases and signaling overhead increases
Solution Approach 1:
The network pre-configures uplink grant resources and associated parameters (power control, MCS, etc.) for the UE while it is in RRC_INACTIVE state. These pre-configured resources are stored in the UE's buffer and can be immediately activated for data transmission without requiring state transition, thereby eliminating the latency associated with RACH procedures and RRC connection setup.
Solution Approach 2:
The patent extracts the essential uplink transmission resources (grant, power control parameters, MCS tables) from the RRC_CONNECTED state configuration and provides them separately to the UE in RRC_INACTIVE state. This allows the UE to perform uplink transmission without needing to transition to connected state, directly reducing the signaling overhead and latency.
2Reliability
If the UE transitions to RRC_CONNECTED state for initial uplink data transmission, then data can be transmitted, but the signaling overhead increases
Solution Approach 1:
The network performs preliminary configuration of all necessary uplink transmission parameters including PUSCH grant, power control settings, and MCS tables before the UE needs to transmit data. This pre-provisioning eliminates the need for extensive signaling exchanges during the transmission process, reducing overhead while maintaining full transmission capability.
Solution Approach 2:
The pre-configured grant resources are designed to be universally applicable for multiple transmission scenarios and purposes. The same pre-configured resources can handle different types of uplink transmissions (data, control information) without requiring additional dedicated configurations, thereby reducing overall signaling overhead.
3Loss of time
If pre-configured grant resources are used for initial transmission in RRC_INACTIVE state, then transmission latency is reduced, but the device complexity increases
Solution Approach 1:
The network performs all complex configuration tasks in advance while the UE is in connected state, including setting up pre-CG resources, power control parameters, and MCS tables. The UE simply stores these configurations and activates them with a single command later, shifting the complexity burden from the UE to the network and minimizing UE processing requirements.
Solution Approach 2:
The network acts as an intermediary that manages the complexity of pre-configured grant resources. Instead of requiring the UE to independently manage complex transmission parameters, the network provisions and controls these resources, simplifying the UE's role to storage and activation of pre-defined configurations.
4Ease of operation
If the UE maintains RRC configuration before entering INACTIVE state, then the configuration is available for quick resumption, but the UE cannot perform dedicated data transmission in INACTIVE state
Solution Approach 1:
The network pre-configures not just the basic RRC parameters but also the specific uplink grant resources needed for data transmission before the UE enters inactive state. This goes beyond simple configuration storage to actually provisioning the transmission resources themselves, enabling immediate data transmission capability upon activation.
Solution Approach 2:
The patent merges the RRC configuration maintenance function with the uplink transmission resource provisioning function. By combining the stored RRC configuration with pre-configured grant resources, the UE achieves both quick state transition capability and immediate data transmission capability without requiring separate mechanisms.
Data Source
AI summary
A user equipment (UE) device including an antenna, a memory, an RF circuitry commutatively coupled to the antenna, and a processor configured to perform operations is described. In an exemplary embodiment, the operations include receiving the one or more pre-configured grant (pre-CG) configurations for an RRC_INACTIVE state from a network node. The one or more pre-CG configurations are for an initial data transmission when the UE is in the RRC_INACTIVE state. The operations also include performing, while the UE is in the RRC_INACTIVE state, the initial data transmission using a pre-CG resource based on the received one or more pre-CG configurations. Each of the one or more pre-CG configurations includes a configuration of the pre-CG resource and one or more conditions to use the pre-CG resource. The one or more conditions to use the pre-CG resource include one or more of an access type, a transmission priority, a mapped Logical Channel (LCH)/Dedicated Radio Bearer (DRB)/Quality of Service (QoS) flow, and a valid timing advance (TA).