Power Headroom Reporting for Component Carriers Without Grants
Solution Overview
Problem
Existing power headroom reporting mechanisms in LTE systems employing carrier aggregation face challenges in calculating power headroom for component carriers without valid uplink grants or PUCCH transmissions, as required parameters are not available, hindering efficient power control and resource allocation.
Innovation Solution
The solution involves using predetermined known values by both the user equipment (UE) and the eNodeB to calculate power headroom for component carriers without valid uplink grants or PUCCH transmissions, allowing for the transmission of power headroom reports and enabling the eNodeB to make informed scheduling decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If power headroom reporting is implemented for component carriers without valid uplink grants, then power control accuracy is improved, but system complexity increases due to the need for predetermined known values and calculation mechanisms
Solution Approach 1:
The patent applies preliminary action by pre-configuring predetermined known values (such as reference resource block assignments, modulation schemes, and power parameters) at both the eNodeB and UE before actual power headroom reporting is needed. This allows the UE to calculate power headroom for component carriers without valid uplink grants using these pre-established values, eliminating the need for complex real-time parameter negotiation and reducing calculation complexity during actual operation.
Solution Approach 2:
The patent introduces predetermined known values as intermediaries between the eNodeB and UE for power headroom calculation. These known values serve as a common reference that both parties use to calculate and interpret power headroom reports, enabling accurate power control without requiring direct real-time parameter exchange or complex coordination mechanisms for component carriers without active uplink grants.
2Productivity
If power headroom reports are transmitted for all component carriers including those without valid grants, then resource allocation efficiency is improved, but uplink signaling overhead increases
Solution Approach 1:
The patent applies local quality by enabling power headroom reporting specifically for component carriers where it is most beneficial - particularly for secondary component carriers without valid uplink grants. The eNodeB can selectively request and utilize PHR information based on local scheduling needs and path loss conditions for individual component carriers, rather than uniformly reporting for all carriers, thus optimizing the balance between resource allocation efficiency and signaling overhead.
3Measurement precision
If power headroom calculation uses actual parameters from component carriers without valid grants, then reporting accuracy is improved, but the ability to handle rapid path loss changes is reduced due to parameter unavailability
Solution Approach 1:
The patent applies preliminary action by pre-configuring reference parameters (resource blocks, modulation schemes, power control parameters) that the UE can use to calculate power headroom even when no valid uplink grant exists. This allows the system to maintain reporting accuracy while rapidly adapting to path loss changes, as the predetermined known values are already established and can be immediately used without waiting for grant availability.
Data Source
AI summary
Power headroom reporting and report handling are discussed in the context of a Physical Uplink Shared Channel (PUSCH), on which a user equipment (UE) has no valid uplink grant, and a Physical Uplink Control Channel (PUCCH) on which a UE has no transmission. Under these circumstances, it is not possible to directly calculate one or more parameters which are used to calculate power headroom. Accordingly, exemplary embodiments provide for predetermined, known values to be used by the UE to calculate the power headroom, and by the eNodeB to understand the meaning of a received power headroom report.