User Terminal Cell Reselection for SC-PTM Group Communication
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Solution Overview
Problem
In mobile communication systems, particularly in LTE, ensuring service continuity for group communication services across different transmission schemes like SC-PTM and MBSFN is challenging, especially considering user terminal mobility, as existing technologies lack clear mechanisms for seamless handover and priority management between these schemes.
Innovation Solution
A user terminal and base station system that includes controllers for cell reselection, group communication service notification, and handover management, prioritizing SC-PTM transmission when available, and providing information about neighboring cells offering group communication services via DL-SCH and PDSCH channels, ensuring continuous service reception during mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a user terminal performs cell reselection in RRC idle mode without priority information, then cell selection is based on general criteria, but the terminal cannot preferentially select cells providing SC-PTM transmission for group communication services
Solution Approach 1:
The base station performs preliminary action by including SC-PTM transmission information in system information broadcast before the user terminal needs to perform cell reselection. This allows the terminal to have advance knowledge of which neighboring cells provide SC-PTM services, enabling informed cell selection decisions that maintain service continuity without requiring complex real-time negotiations during handover.
2Reliability
If the base station transmits detailed SC-PTM service information to all user terminals, then terminals can make informed cell selection, but system information broadcast overhead increases
Solution Approach 1:
The patent extracts only the essential SC-PTM transmission information (such as cell identifiers and service availability indicators) from the complete service description and includes only these extracted elements in the system information broadcast. This allows user terminals to make informed cell selection decisions without receiving unnecessary detailed service information, thereby reducing system information overhead while maintaining service continuity capability.
3Adaptability or versatility
If the system supports both SC-PTM and MBSFN transmission schemes, then service coverage is enhanced, but the complexity of managing handovers and service continuity between different schemes increases
Solution Approach 1:
The patent implements a universal cell selection mechanism that works across both SC-PTM and MBSFN transmission schemes. By using a common approach where user terminals acquire transmission scheme information from system information and apply the same priority-based cell reselection logic, the system achieves multi-functionality without requiring separate handover management procedures for each transmission scheme, thereby reducing overall complexity.
Data Source
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AI summary
A user terminal according to one embodiment comprises a controller configured to perform cell reselection in a RRC idle mode. The controller is configured to when having an interest in reception of a group communication service provided in one frequency over SC-PTM transmission, preferentially select a cell belonging to the one frequency during the cell reselection.