RRC Idle Mode Uplink Transmission via Preconfigured Resources
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Solution Overview
Problem
Current wireless communication systems, particularly in NB-IoT, fail to effectively reduce power consumption in IoT devices as they often require frequent switching between RRC idle and connection states for uplink message transmission, leading to increased signaling exchange and power consumption.
Innovation Solution
A mechanism where a user equipment (UE) performs a random access procedure with a base station (BS) to preconfigure an uplink resource and starts a dedicated time alignment timer in RRC idle mode, allowing for direct uplink message transmission on the preconfigured resource if the timing advance value is valid, thereby reducing the need for frequent state changes and signaling exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE switches to RRC connection state to transmit uplink messages, then the uplink message transmission can be completed, but the power consumption increases due to frequent state switching and signaling exchange
Solution Approach 1:
The base station pre-configures uplink resources for the UE in RRC idle state before actual data transmission is needed. This preliminary configuration includes allocating specific time-frequency resources and providing relevant parameters, so that when the UE has data to transmit, it can immediately use the pre-configured resources without needing to switch to RRC connection state, thereby reducing power consumption and signaling overhead
Solution Approach 2:
The patent extracts the resource configuration process from the traditional RRC connection establishment procedure. By separating the resource pre-configuration from the connection setup, the UE can obtain uplink resources while remaining in RRC idle state, eliminating the need for frequent state transitions and reducing the signaling exchange associated with connection management
2Loss of energy
If the BS configures one-time radio resource for UE in EDT procedure, then the signaling exchange is reduced, but the UE cannot transmit subsequent uplink messages without switching to RRC connection state
Solution Approach 1:
The pre-configured uplink resources are designed to serve multiple purposes and multiple transmission instances. Instead of allocating resources for a single transmission, the base station configures resources that can be reused by the UE for multiple uplink message transmissions while remaining in RRC idle state, making the resource allocation more versatile and reducing the need for repeated connection setups
Solution Approach 2:
The UE is empowered to autonomously use the pre-configured uplink resources whenever it has data to transmit, without needing to request additional resources or switch states. The UE can independently determine when to transmit on the pre-configured resources, making the system more self-service oriented and reducing control signaling overhead
3Productivity
If the UE frequently switches between RRC idle and connection states, then the uplink message transmission can be accomplished, but the signaling exchange increases and power consumption rises
Solution Approach 1:
The base station performs resource configuration in advance during RRC idle state, so that when the UE needs to transmit data, the resources are already allocated and ready for immediate use. This eliminates the time-consuming process of resource request and allocation that would otherwise occur during connection establishment, reducing both signaling exchange time and power consumption
Data Source
AI summary
A user equipment (UE) and a base station (BS) for a mobile communication system are provided. The UE performs a random access (RA) procedure with the BS in a radio resource control (RRC) idle mode. The UE transmits a preconfigured uplink resource request message to the BS and receives a configuration message indicating a preconfigured uplink resource from the BS. The UE starts a time alignment timer (TAT) which is used for the RRC idle mode in response to the RA procedure. When the UE determines that there exists an uplink message to be transmitted in the RRC idle mode and determines that the current timing advance (TA) value is valid, the UE transmits the uplink message on the preconfigured uplink resource.