Terminal CSI Triggering for Multi-TRP Cell Mobility

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Solution Overview

Problem

In radio communication systems with multi-TRP scenarios, the appropriate performance of CSI reporting during L1/L2 inter-cell mobility is unclear, leading to potential reductions in communication throughput.

Innovation Solution

A terminal is equipped with a control section that transmits a specific indication from the physical layer to the MAC layer, counts this indication, and triggers an aperiodic CSI report based on a counter value, ensuring appropriate CSI reporting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If L1/L2 inter-cell mobility is applied in multi-TRP scenarios, then serving cell switching capability is improved, but CSI reporting accuracy deteriorates due to unclear reporting mechanisms

Engineering Contradiction:

Improveserving cell switching capabilityVSAvoidCSI reporting accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the CSI reporting process by introducing separate reporting mechanisms for different cells. The terminal device performs CSI reporting separately for the first cell (source cell) and second cell (target cell) during handover, ensuring accurate channel state information is available for both cells independently. This segmentation resolves the contradiction by maintaining measurement precision while enabling adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by having the terminal device perform CSI reporting for the target cell before the handover is completed. The terminal reports CSI for the second cell in advance, allowing the network to make informed decisions about resource allocation and beam management prior to the actual serving cell switch, thus maintaining accuracy during the mobility transition.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If multi-TRP transmission is implemented, then communication capacity is improved, but system complexity increases due to multiple cells performing DL transmission

Engineering Contradiction:

Improvecommunication capacityVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the management of multiple TRPs under a unified handover framework. Instead of creating separate complex control mechanisms for each TRP, the patent combines them into the existing L1/L2 handover procedure, where the terminal switches serving cells between TRPs using standardized signaling. This merging maintains high communication capacity while reducing system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the handover mechanism universal by applying the same L1/L2 handover procedure for switching between serving cells in multi-TRP scenarios as is used for traditional single-TRP handovers. The existing handover signaling and CSI reporting mechanisms are extended to handle multiple TRPs, avoiding the need for new specialized protocols and thus reducing system complexity while maintaining productivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20260107175A1Terminal, radio communication method, and base station

Publication Date: 2026.04.16 NTT DOCOMO INC

AI summary

A terminal according to an aspect of the present disclosure includes: a control section that transmits, when a Layer 1 (L1) measurement result meets a condition, a specific indication from a physical layer to a Medium Access Control (MAC) layer, counts the specific indication in the MAC layer, and triggers, based on a counter value, an aperiodic CSI report; and a transmitting section that transmits the aperiodic CSI report. An aspect of the present disclosure enables CSI reporting to be appropriately performed.