Power Headroom Report Compression for Uplink Carrier Aggregation
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Solution Overview
Problem
In radio communication systems using uplink carrier aggregation, the existing power headroom reporting (PHR) methods require a significant data amount for transmission, which increases processing load for base stations, and there is a need to optimize this for efficient resource scheduling.
Innovation Solution
A mobile station and base station system that transmits and receives a power headroom report including a power difference between maximum transmission powers of different uplink carriers, reducing the number of information elements needed for reporting and processing, such as using a power difference ΔPCMAX=PCMAX,2−PCMAX,1, and optionally omitting maximum transmission power information, to minimize data amount and processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detailed maximum transmission power information (PCMAX,1 and PCMAX,2) is transmitted for each uplink carrier, then the base station can perform accurate power headroom calculation and resource scheduling, but the data amount of PHR increases significantly
Solution Approach 1:
The patent extracts only the necessary information for power headroom calculation by transmitting the power difference (ΔPCMAX) between carriers instead of absolute PCMAX values for each carrier. This allows the base station to derive the required power headroom information using the received ΔPCMAX combined with its own knowledge of PCMAX,1, thereby reducing PHR data amount while maintaining calculation accuracy.
Solution Approach 2:
The patent changes the reporting parameter from absolute maximum transmission power values (PCMAX,1 and PCMAX,2) to a relative power difference parameter (ΔPCMAX = PCMAX,2 - PCMAX,1). This parameter transformation reduces the information content while preserving the essential power headroom calculation capability, as the base station can reconstruct the needed values using its stored PCMAX,1 information.
2Productivity
If complete power headroom information including PCMAX for each carrier is reported, then the base station can optimize uplink resource allocation, but the processing load and complexity increase
Solution Approach 1:
The patent extracts only the essential power difference information (ΔPCMAX) needed for resource allocation decisions, removing redundant absolute power value transmissions. This reduces the processing complexity at the base station while maintaining the capability to optimize uplink resource allocation, as the base station can calculate power headroom using its existing PCMAX,1 knowledge combined with the received ΔPCMAX.
3Loss of information
If all power headroom parameters (PCMAX,1, PCMAX,2, PH,1, PH,2) are transmitted, then comprehensive power status information is available, but the PHR message size becomes large
Solution Approach 1:
The patent extracts and transmits only the power difference parameter (ΔPCMAX) that captures the essential relationship between carrier powers. This allows the base station to reconstruct complete power status information using its stored PCMAX,1 value and the received ΔPCMAX, thereby maintaining information completeness while significantly reducing PHR message size by eliminating redundant absolute power value transmissions.
Data Source
AI summary
A mobile station (1) has a capability to communicate with a base station (2) simultaneously using activated first and second uplink carriers. The mobile station (1) is configured to transmit a power headroom report to the base station (2). The power headroom report includes an information element (ΔPPUSCH) indicating a power difference between first maximum transmission power of the mobile station (1) for the first uplink carrier and second maximum transmission power of the mobile station (1) for the second uplink carrier. It is thus, for example, possible to provide improvement of power headroom reporting (PHR) suitable for uplink carrier aggregation.