Terminal PRACH Power Ramping for PDCCH-Ordered Cell Switching

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Solution Overview

Problem

In future radio communication systems, the control of power ramping during inter-cell mobility is unclear, leading to potential degradation of communication throughput due to inappropriate random access procedures.

Innovation Solution

A terminal that receives a downlink control channel order to decide on power ramping for random access channel transmission, enabling appropriate control of power ramping during mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple RACH procedures are performed in parallel without clear power ramping control, then random access capability is maintained across multiple cells, but power ramping management becomes unclear and communication throughput degrades

Engineering Contradiction:

Improverandom access capabilityVSAvoidcommunication throughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent segments the power ramping control by assigning separate power ramping counters (PREAMBLE_POWER_RAMPING_COUNTER) for each candidate cell. This allows independent tracking and management of power ramping state for each RACH procedure, enabling clear control while maintaining parallel operations across multiple cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic power ramping control where the power ramping counter is updated based on RACH procedure outcomes for each candidate cell. The counter increments when RACH fails and resets when successful, allowing adaptive power adjustment that responds to real-time channel conditions while maintaining parallel RACH procedures.

Inventive Principle:

Principle #15Dynamics

2Productivity

If power ramping is not properly controlled during inter-cell mobility, then device complexity is reduced, but communication throughput degrades

Engineering Contradiction:

Improvecommunication throughputVSAvoidpower ramping control complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The terminal autonomously manages power ramping for each candidate cell by maintaining separate power ramping counters and automatically updating them based on RACH procedure outcomes. This self-service mechanism eliminates the need for complex network-controlled power ramping management while ensuring appropriate power adjustment for optimal throughput.

Inventive Principle:

Principle #25Self-service

3Reliability

If power ramping counter is not reset after successful RACH, then power management becomes simpler, but random access reliability degrades

Engineering Contradiction:

Improverandom access reliabilityVSAvoidpower ramping management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback mechanisms where the power ramping counter for each candidate cell is updated based on RACH procedure outcomes. When RACH succeeds, the counter resets to 0; when it fails, the counter increments. This feedback-driven approach ensures reliable random access by adapting power levels to actual channel conditions while maintaining manageable complexity through standardized counter operations.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP4712594A1Terminal, wireless communication method, and base station

Publication Date: 2026.03.18 NTT DOCOMO INC

Figure 1A~1B
Figure 2
Figure 3A~3B

AI summary

A terminal according to one aspect of the present disclosure includes: a receiving section that receives a downlink control channel (PDCCH) order for a candidate cell; and a control section that decides to perform power ramping for random access channel (PRACH) transmission, based on the PDCCH order.