RACH-Less Handover PUSCH Association With Target-Cell Reference Signals

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Solution Overview

Problem

In RACH-less handover processes in LTE and NR, the association between physical uplink shared channel (PUSCH) transmission and downlink signals is not considered, leading to challenges in determining reference signals, timing advance validation, available transmission occasions, power, redundancy version, and potential transmission conflicts.

Innovation Solution

Establishing an association relationship between the resource of the first PUSCH and a reference signal of the target cell, including configured grant and dynamic grant scenarios, and determining timing advance information to facilitate reliable RACH-less handover.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If RACH-less handover is implemented to reduce signaling overhead and delay, then handover efficiency is improved, but the association between PUSCH transmission and downlink signals becomes unclear leading to reliability issues

Engineering Contradiction:

Improvehandover efficiencyVSAvoidcommunication reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-establishing the association relationship between PUSCH resources and downlink reference signals before handover execution. The network device configures the terminal with reference signal resources and association rules in advance, enabling the terminal to determine uplink transmission parameters without random access signaling during handover, thus maintaining both efficiency and reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces downlink reference signals (SSB or CSI-RS) as intermediaries to establish the association relationship with PUSCH resources. These reference signals serve as mediators that enable the terminal to determine timing advance and transmission parameters without direct random access signaling, resolving the reliability issue while maintaining RACH-less efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If beamforming is not considered in LTE RACH-less handover to simplify the process, then device complexity is reduced, but transmission efficiency and reliability deteriorate

Engineering Contradiction:

Improvehandover process complexityVSAvoidtransmission efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent applies parameter changes by introducing downlink reference signal parameters (SSB or CSI-RS) and their association with PUSCH resources as new configuration parameters. This allows the system to incorporate beamforming capabilities through parameter configuration without fundamentally changing the LTE handover procedure structure, thus improving transmission efficiency while controlling complexity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260067768A1Transmission method, terminal, network side device and medium

Publication Date: 2026.03.05 VIVO MOBILE COMM CO LTD

AI summary

Provided are a transmission method, a terminal, a network-side device, and a medium. The transmission method includes: transmitting, by a terminal, a first physical uplink shared channel PUSCH to a target cell in a random access channel-less RACH-less handover process, where there is an association relationship between a resource of the first PUSCH and a first reference signal of the target cell.