Base Station Cross-Frequency Discovery Signal Permission
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Solution Overview
Problem
The effective utilization of Device to Device Proximity Service (D2D ProSe) in mobile communication systems is hindered due to inadequate specifications for D2D ProSe relaying, particularly in scenarios where a radio terminal needs to transmit a discovery signal outside the coverage of the serving cell, leading to inefficient signal transmission.
Innovation Solution
A base station and radio terminal system where the base station receives a request from the radio terminal to transmit a discovery signal in a different frequency band and determines permission based on the signal reception level, allowing transmission only if the level is below a threshold, and specifies the necessary radio resources for the transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a radio terminal transmits a discovery signal outside the coverage of the serving cell, then the communication range is extended, but interference with other frequency band operations increases
Solution Approach 1:
The base station changes the parameter of frequency band allocation by permitting discovery signal transmission in a second frequency band different from the serving cell's first frequency band. This parameter change enables extended communication range while managing interference through controlled frequency selection based on reception level thresholds.
2Productivity
If permission for cross-frequency discovery signal transmission is freely granted, then D2D ProSe utilization is improved, but signal quality control deteriorates
Solution Approach 1:
The base station implements a feedback-based permission system where it receives a permission request message from the radio terminal and responds with permission or non-permission based on the reception level. This feedback mechanism ensures that D2D ProSe utilization is improved while maintaining signal quality control through centralized base station authorization.
3Productivity
If discovery signal transmission is permitted in a different frequency band, then the effectiveness of D2D ProSe is enhanced, but base station control complexity increases
Solution Approach 1:
The base station extracts the permission control function from the general cell management functions, creating a specific permission request and determination mechanism for cross-frequency discovery signal transmission. This extracted control mechanism enhances D2D ProSe effectiveness while managing complexity by focusing control on the specific permission decision based on reception level thresholds.
Data Source
Figure 1
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Figure 4
AI summary
A base station according to a present embodiment manages a cell operated in a first frequency band. The base station comprises: a receiver configured to receive, from a radio terminal connecting to the cell, a message requesting permission for the radio terminal to transmit a discovery signal in a second frequency band different from the first frequency band; and a controller configured to determine whether to permit transmission of the discovery signal in the second frequency band.