Terminal D2D Bearer Control During Radio Link Failure
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Solution Overview
Problem
Current cell reselection procedures in device-to-device communication are inefficient, particularly when a terminal apparatus experiences radio link failures, leading to wasteful resource allocation and difficulty in maintaining effective D2D communication.
Innovation Solution
A terminal apparatus that performs data communication with a base station and device-to-device communication, using a radio resource configured by the base station, selectively continues, suspends, or releases device-to-device data radio bearers based on the ability to perform D2D communication in the cell and the presence of D2D data, optimizing connection control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cell reselection procedure is used to prioritize D2D frequencies, then D2D communication ability is improved, but connection re-establishment efficiency deteriorates when radio link fails
Solution Approach 1:
The patent dynamically adjusts the cell selection procedure based on the terminal's D2D communication state. When D2D communication is active, the terminal prioritizes frequencies that support D2D during connection re-establishment, rather than using static frequency priority. This dynamic adaptation resolves the contradiction by making the system flexible enough to maintain both D2D capability and re-establishment efficiency.
Solution Approach 2:
The patent changes the frequency selection parameters during connection re-establishment based on D2D communication requirements. Specifically, it modifies which frequencies are prioritized in the cell selection process when the terminal needs to re-establish connection after radio link failure, ensuring that D2D-capable frequencies are selected first when D2D data is present.
2Reliability
If terminal tries radio connection in new cell after radio link failure, then connection is restored, but D2D communication resources are wasted
Solution Approach 1:
The patent performs preliminary assessment of D2D communication capability in the target cell before the terminal commits to radio connection re-establishment. By checking whether the selected cell supports D2D communication and whether D2D data exists in the terminal beforehand, the system avoids unnecessary connection attempts that would waste D2D resources, while still ensuring reliable connection restoration when appropriate.
Solution Approach 2:
The terminal autonomously determines whether to attempt connection re-establishment based on its own D2D communication state and the capabilities of the detected cell. The terminal serves itself by making intelligent decisions about resource allocation, avoiding wasteful connection attempts to cells that cannot support D2D when D2D communication is active.
3Productivity
If cell selection procedure is used for connection re-establishment, then connection recovery is achieved, but D2D communication efficiency deteriorates
Solution Approach 1:
The patent modifies the cell selection parameters specifically for connection re-establishment scenarios when D2D communication is active. It changes the frequency priority and selection criteria to favor cells that support D2D, ensuring that connection recovery does not compromise D2D communication efficiency. This parameter adjustment resolves the contradiction by making the cell selection process aware of D2D requirements.
Data Source
AI summary
Provided is a technique related to a terminal apparatus, a control method, and an integrated circuit that are able to efficiently perform connection control when performing device-to-device communication. At a time of re-establishing radio resource control connection, at least on a basis of whether or not device-to-device data communication is able to be performed in a selected cell and whether or not there is data of the device-to-device data communication in the terminal apparatus, the terminal apparatus selects information about the device-to-device data communication, which is to be notified to the base station apparatus.