Power Headroom Reporting for Carrier Aggregation
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Solution Overview
Problem
The existing power headroom reporting methods in mobile communication systems supporting carrier aggregation are inefficient, particularly in determining and transmitting power headroom information for multiple uplink carriers, as they are designed for single carrier scenarios and struggle to adapt to the complexities of carrier aggregation.
Innovation Solution
A method and apparatus for efficiently transmitting and receiving power headroom information by acquiring path loss reference information, triggering power headroom reports when path loss changes exceed a threshold, and obtaining power headroom information for each activated cell, especially when extended power headroom reports are used and uplink resources are allocated for new transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If existing power headroom reporting methods designed for single carrier are used in carrier aggregation systems, then device complexity is reduced, but power headroom information accuracy and completeness deteriorate
Solution Approach 1:
The patent segments the power headroom reporting mechanism by introducing separate path loss reference configurations for different uplink carriers. Each uplink carrier can independently reference a downlink carrier for path loss calculation, allowing differentiated power headroom reporting per carrier while maintaining manageable device complexity through structured segmentation of the reporting framework.
Solution Approach 2:
The patent adds a new dimension to power headroom reporting by introducing the path loss reference carrier selection mechanism. Instead of a single unified power headroom value, the system now operates in a multi-dimensional space where each uplink carrier's power headroom is evaluated relative to its designated downlink reference carrier, enabling comprehensive multi-carrier power management.
2Measurement precision
If path loss reference is changed frequently to adapt to carrier aggregation, then power headroom information accuracy improves, but signaling overhead and system complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring path loss reference relationships between downlink and uplink carriers through higher layer signaling before actual power headroom reporting occurs. This advance configuration establishes the reference framework in advance, allowing the UE to efficiently determine path loss references without complex real-time decisions, thereby improving accuracy while controlling complexity.
Solution Approach 2:
The system implements feedback mechanisms where the network can adjust path loss reference configurations based on UE reports and channel conditions. This feedback loop allows dynamic optimization of path loss reference selection, ensuring accurate power headroom measurements while adapting to changing carrier aggregation scenarios without requiring excessive signaling overhead.
3Reliability
If power headroom reports are triggered frequently to capture path loss changes, then transmission quality improves, but uplink resource overhead increases
Solution Approach 1:
The patent utilizes parameter changes by introducing a path loss change threshold as a trigger condition for power headroom reporting. Instead of reporting at fixed intervals or unconditionally, the system monitors path loss variations and triggers reports only when changes exceed the configured threshold, thereby maintaining transmission quality through timely updates while significantly reducing unnecessary signaling overhead.
Data Source
AI summary
A Power Headroom Report (PHR) method and apparatus in a communication system are provided. The method includes acquiring information for a path loss reference, wherein the information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell), triggering a power headroom report (PHR) if a path loss is changed more than a threshold for at least one activated cell which is used as the path loss reference, and obtaining power headroom information for each activated cell, if extended PHR is used and an uplink resource is allocated for new transmission.