Uplink Power Control for Different TTI Length Carrier Aggregation

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Solution Overview

Problem

Current LTE technologies lack a method to calculate the lower and upper limits of maximum transmission power (P CMAX_L and P CMAX_H) when carrier aggregation is performed between cells with different TTI lengths, as existing calculation methods assume same subframe lengths.

Innovation Solution

A user device and communication method that calculate P CMAX_L and P CMAX_H using formulas that account for different TTI lengths by defining subframes of one TTI length as a reference and combining them with subframes of another TTI length, ensuring constant maximum transmission power in each subframe to prevent demodulation accuracy degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If carrier aggregation is performed between cells with different TTI lengths, then communication flexibility and data transfer rate are improved, but the calculation of maximum transmission power limits becomes undefined and demodulation accuracy degrades

Engineering Contradiction:

Improvedata transfer rateVSAvoiddemodulation accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the calculation parameters for maximum transmission power by introducing TTI length as a variable factor. It defines different calculation formulas for P_CMAX_L and P_CMAX_H based on whether the component carriers have the same or different TTI lengths, thereby adapting the power calculation to the specific TTI configuration of the carrier aggregation scenario

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the power calculation process into different cases: one for component carriers with the same TTI length and another for component carriers with different TTI lengths. This segmentation allows the system to apply appropriate calculation methods for each scenario, ensuring accurate power limit determination while maintaining demodulation accuracy

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If existing power calculation formulas are used for different TTI lengths, then calculation simplicity is maintained, but transmission power becomes unstable and communication quality degrades

Engineering Contradiction:

Improvecalculation simplicityVSAvoidtransmission power stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent introduces dynamic adaptation into the power calculation system by making the calculation formula dependent on the TTI length configuration. The system dynamically selects between different calculation approaches based on the actual carrier aggregation scenario, ensuring transmission power stability while accommodating varying TTI lengths

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3340698B1User device, base station, communication method, and instruction method

Publication Date: 2023.03.08 NTT DOCOMO INC

Figure 1(a1)~1(b2)
Figure 2(a)~2(b)
Figure 3

AI summary

A user device for a radio communication system supports uplink carrier aggregation. The user device includes a transmitter that transmits an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and a calculator that calculates a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe.