Virtual Power Headroom Reporting for MTC Devices

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Solution Overview

Problem

In enhanced coverage mode, user equipment (UE) in poor radio conditions often operates at maximum power, making traditional power headroom reporting of limited use, as it frequently indicates zero or negative power headroom, which does not provide valuable information for base station scheduling.

Innovation Solution

The UE adapts power headroom reporting by preparing virtual power headroom reports when in enhanced coverage mode, including information based on virtual scheduled uplink grants, even without actual grants, to provide pathloss information useful for scheduling, and optionally includes a power-limitation indicator or repetition levels in the report.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If traditional power headroom reporting is used in enhanced coverage mode, then the reporting mechanism remains simple and compatible with existing systems, but the reported information becomes meaningless (zero or negative power headroom) and fails to provide useful scheduling information

Engineering Contradiction:

Improveusefulness of power headroom reportVSAvoidcomplexity of power headroom reporting mechanism

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent changes the parameter being reported from actual power headroom (which is zero or negative in enhanced coverage mode) to virtual power headroom calculated based on pathloss. This parameter transformation maintains the reporting structure while providing meaningful information about channel conditions and power limitations to the base station for better scheduling decisions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces pathloss as an intermediary measurement to derive virtual power headroom information. Instead of directly reporting the useless actual power headroom, the system uses pathloss (a measurable channel characteristic) as a mediator to infer and report virtual power headroom, which indirectly conveys the power-limited status and channel conditions without requiring complex new measurement mechanisms

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If UE transmits at maximum power in poor radio conditions, then coverage is maximized, but power headroom becomes zero or negative making the report useless for scheduling optimization

Engineering Contradiction:

Improvecoverage in poor radio conditionsVSAvoidscheduling information from power headroom report

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

Instead of reporting the direct power headroom value (which is zero or negative when transmitting at maximum power), the patent inverts the approach by calculating virtual power headroom based on pathloss measurements. This inversion allows the system to report meaningful channel state information even when the UE is power-limited, thereby preserving scheduling optimization capability while maintaining maximum power transmission for coverage

Inventive Principle:

Principle #13The other way round (Inversion)

3Loss of information

If virtual power headroom reports are prepared for all UEs in enhanced coverage mode, then useful channel state information is provided for scheduling, but processing overhead increases at the UE

Engineering Contradiction:

Improvechannel state information availabilityVSAvoidprocessing energy at UE

Core Design Contradiction:

Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent makes the existing pathloss measurement mechanism serve a dual purpose: it continues to provide pathloss information for uplink power control while simultaneously enabling the calculation of virtual power headroom for reporting. This multi-functionality avoids introducing separate measurement mechanisms, thereby providing useful channel state information without significantly increasing UE processing energy consumption

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10178632B2Power headroom reporting for MTC devices in enhanced coverage mode

Publication Date: 2019.01.08 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

The present disclosure relates various embodiments for improving power headroom reporting for UEs being in an enhanced coverage mode. The UE may be configured to always transmit a virtual power headroom report to the eNB, when operating in the enhanced coverage mode. Or, the UE may be configured to always transmit a virtual power headroom report to the eNB, when operating in the enhanced coverage mode and at the same time being power limited. Moreover, the UE may determine a repetition level for transmissions in the uplink and/or may determine a repetition level for transmissions in the downlink. The power headroom report can then be used to transport this information (either one of, or both of, the uplink/downlink repetition levels), by using predefined codepoints in the power headroom report.