User Terminal SCell Activation via DCI Extraction
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Solution Overview
Problem
Legacy LTE systems require several tens of milliseconds to activate Secondary Cells (SCells), which hampers throughput and necessitates a faster activation/deactivation method for future radio communication systems like NR.
Innovation Solution
A user terminal with a receiving section for downlink control information and a control section that manages cell activation and channel state measurement based on DCI, including activation commands, CSI measurement triggers, CSI reporting requests, SRS Resource Index, and A-SRS transmission triggers, allowing for quicker control of SCell activation/deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MAC CE is used to activate SCell in legacy LTE, then the SCell can be activated from deactivated state, but the activation time requires several tens of milliseconds which is too slow for future radio communication systems
Solution Approach 1:
The invention extracts the SCell activation command from the MAC CE layer and places it directly in the DCI (Downlink Control Information) at the physical layer. This extraction allows the activation command to be transmitted more quickly through the physical channel rather than waiting for MAC layer processing, thereby reducing the activation time from several tens of milliseconds to a much shorter duration.
Solution Approach 2:
The invention introduces a new intermediary mechanism by using DCI format 0 with a specific field (e.g., 2-bit field) to carry the SCell activation command. This DCI-based intermediary bypasses the slower MAC CE path and enables faster transmission of activation commands through the physical downlink control channel, resolving the time delay issue.
2Productivity
If faster SCell activation is implemented, then throughput can be improved, but the system complexity increases due to new DCI formats and control mechanisms
Solution Approach 1:
The invention makes the DCI format 0 multi-functional by enabling it to carry both uplink scheduling information and SCell activation commands. The same DCI structure is used for different purposes: normal uplink grants and SCell activation/deactivation commands. This universality avoids creating entirely new complex signaling structures while still achieving fast activation.
Solution Approach 2:
The invention changes the parameter interpretation of existing DCI fields. For example, specific bit combinations in the DCI format (such as 2-bit fields) are reinterpreted to indicate SCell activation commands rather than just uplink scheduling parameters. This parameter change allows existing DCI structures to convey new functionality without adding significant complexity.
Data Source
AI summary
A user terminal according to one aspect of the present disclosure includes: a receiving section that receives downlink control information on a downlink control channel, the downlink control information including information related to activation of a cell and information related to a trigger of channel state measurement; and a control section that controls the activation of the cell based on the information related to the activation, and controls the channel state measurement of the cell based on the information related to the trigger of the channel state measurement. According to the one aspect of the present disclosure, it is possible to control activation at a high speed.