Uplink Transmit Power Control via Subframe Offset Signaling
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Solution Overview
Problem
In mobile communication systems, especially in time-domain inter-cell interference coordination, accurate transmit power control is challenging due to varying interference signal sizes across subframes, leading to frequent and inaccurate signaling for transmit power control.
Innovation Solution
The method involves creating a subframe offset of transmit power (SOTP) based on resource allocation information from adjacent cells, which is then transmitted to terminals, allowing them to correct uplink transmit power for each subframe, reducing signaling complexity and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-domain ICIC is implemented with frequent TPC signaling to coordinate interference for each subframe, then inter-cell interference coordination is improved, but signaling overhead and system complexity increase
Solution Approach 1:
The patent segments subframes into two categories: normal subframes and Almost Blank Subframes (ABS). This segmentation allows different transmit power control strategies to be applied to different subframe types, reducing the need for frequent TPC signaling while maintaining effective interference coordination. By dividing the subframe structure, the system can coordinate interference without requiring individual TPC commands for every subframe.
Solution Approach 2:
The patent applies preliminary action by pre-configuring ABS patterns and notifying terminals of upcoming ABS positions in advance. This allows terminals to proactively adjust their transmit power for subframes following ABS based on predicted interference conditions, rather than waiting for reactive TPC commands. The advance notification mechanism enables power adjustment before the interference situation actually occurs.
2Measurement precision
If TPC signaling is sent frequently to adjust transmit power for each subframe, then transmit power control accuracy is improved, but the number of signaling commands increases
Solution Approach 1:
The patent merges the transmit power control functionality into the existing ABS configuration signaling. Instead of sending separate TPC commands for each power adjustment, the ABS position information and power adjustment parameters are combined into a single signaling message. This merging reduces the total number of signaling commands while maintaining the ability to accurately control transmit power based on interference conditions.
Solution Approach 2:
The patent changes the parameter representation by introducing SOTP (Subframe Offset for Transmit Power) as a new parameter that directly indicates power adjustment for specific subframes. This parameter change allows the system to convey multiple power control instructions more efficiently by encoding them in a compact format rather than using multiple separate TPC commands.
3Stability of the object's composition
If transmit power control range is limited to previously set values, then system stability is improved, but accurate power control becomes difficult when interference exceeds the control range
Solution Approach 1:
The patent introduces dynamics by making the transmit power control adaptive to varying interference conditions. The SOTP parameter allows the system to dynamically adjust power control ranges based on actual interference levels, particularly for subframes following ABS where interference patterns change. This dynamic approach enables accurate power control even when interference exceeds previously set control ranges, while maintaining system stability through structured adjustment mechanisms.
Data Source
AI summary
Disclosed is a method for controlling uplink transmit power in a mobile communication system. A mobile communication includes a first base station and a second base station which are located in two mutually adjacent cells, respectively, at least one base station of the first and second base stations which generate a subframe offset of transmit power (SOTP), and transmits a subframe offset of transmit power generated by at least one base station of the first and second base stations to at least one terminal which belongs to a corresponding cell. Accordingly, it is possible to reduce signaling times for transmit power control, and to accurately control transmit power.