Dynamic Transmit Power Control for FDD-TDD Dual Connectivity

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Solution Overview

Problem

In wireless communication systems with dual connectivity, particularly FDD-TDD dual connectivity, the aggregate instantaneous transmit power across FDD and TDD air interfaces is capped by the SAR limit, limiting the ability to improve uplink communication quality and speed due to restrictions on duty cycle and power levels, leading to potential coverage holes and increased latency.

Innovation Solution

The UE divides its FDD and TDD air interfaces into equal-length time intervals shorter than the SAR window, using the actual transmit power in each FDD interval to set the maximum transmit power in subsequent TDD intervals, ensuring the average aggregate power remains within the SAR limit while potentially increasing TDD transmit power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the aggregate instantaneous transmit power is capped by the SAR limit, then the safety requirement is met, but the uplink communication quality and speed deteriorate

Engineering Contradiction:

ImproveSAR limit complianceVSAvoiduplink communication quality and speed

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent segments the transmit power control into two independent dimensions: FDD transmit power and TDD transmit power. By dividing the power management into separate controllable entities rather than treating aggregate power as a single constraint, the system can optimize each air interface independently while ensuring their sum remains within SAR limits, thereby improving uplink communication quality without compromising safety

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic transmit power adjustment where the FDD and TDD transmit powers are continuously adapted based on real-time channel conditions, traffic requirements, and SAR constraints. This dynamic control allows the system to maximize uplink communication performance by adjusting power levels adaptively rather than using fixed power caps, thereby resolving the contradiction between safety compliance and communication quality

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the duty cycle is restricted to meet SAR limits, then the safety requirement is met, but the latency increases

Engineering Contradiction:

ImproveSAR limit complianceVSAvoidlatency

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent segments the duty cycle control into separate FDD and TDD duty cycles that can be independently optimized. By treating each air interface's duty cycle as an independent controllable parameter rather than being constrained by a unified aggregate duty cycle limit, the system can reduce overall latency while ensuring that the combined SAR exposure remains within safety limits

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic duty cycle adjustment where FDD and TDD transmission opportunities are adaptively scheduled based on real-time conditions. This allows the system to minimize latency by increasing transmission opportunities when channel conditions permit, while dynamically ensuring SAR compliance, rather than using fixed restrictive duty cycle limits

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If the transmit power level is reduced to meet SAR limits, then the safety requirement is met, but the coverage holes increase

Engineering Contradiction:

ImproveSAR limit complianceVSAvoidcoverage continuity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the power control into independent FDD and TDD transmit power parameters that can be separately optimized. This segmentation allows the system to maintain higher transmit power levels on each individual air interface while ensuring their aggregate remains within SAR limits, thereby improving coverage reliability without compromising safety

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic transmit power adjustment that adapts to real-time channel conditions and traffic requirements. This dynamic control enables the system to maintain adequate coverage by adjusting power levels adaptively rather than using fixed reduced power settings, thereby resolving the contradiction between SAR compliance and coverage continuity

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11503554B2Dynamically accounting for past transmit power as basis to set future transmit power on co-existing air interface

Publication Date: 2022.11.15 SPRINT SPECTRUM LLC

AI summary

A method and system for controlling uplink transmit power of a UE when the UE is served concurrently on at least two air interfaces including a first air interface and a second air interface. An example method includes, iteratively for each successive given time interval of a continuum of equal-duration time intervals, (i) determining an actual average transmit power of the UE on the first air interface over the given time interval, (ii) using the determined actual average transmit power of the UE on the first air interface over the given time interval as a basis to set a maximum average transmit power of the UE for transmission on the second air interface in a respective subsequent time interval, and (iii) applying the set maximum average transmit power as a limitation on uplink transmit power of the UE for the transmission on the second air interface in the respective subsequent time interval.