Time Alignment Timer for Uplink Signal Synchronization

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Solution Overview

Problem

In mobile communication systems like 3GPP LTE, terminals face issues when receiving signals for uplink signal transmission or downlink signal reception while their uplink signal transmission timing is incorrect, leading to potential malfunctions and interference.

Innovation Solution

Implementing a time alignment timer mechanism that ensures terminals only process uplink grant signals or transmit downlink signals when the time alignment timer is running, preventing unnecessary random access procedures and maintaining synchronization with the base station.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If terminals process uplink grant signals or transmit downlink signals without checking time alignment timer status, then communication operations can proceed without timing verification, but this causes malfunctions and interference due to incorrect uplink signal transmission timing

Engineering Contradiction:

Improvecommunication operation continuityVSAvoidtiming alignment accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The terminal checks the time alignment timer status before processing uplink grant signals or transmitting downlink signals. This preliminary verification ensures that timing alignment is confirmed prior to communication operations, preventing malfunctions and interference caused by incorrect timing while maintaining operational continuity when timing is proper

Inventive Principle:

Principle #10Preliminary action

2Reliability

If terminals continuously maintain time alignment monitoring, then timing accuracy is preserved, but this increases system complexity and resource consumption

Engineering Contradiction:

Improvetiming synchronization accuracyVSAvoidtime alignment management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The terminal monitors time alignment periodically based on timer status rather than continuously. The time alignment timer is updated at specific intervals through random access procedures or uplink signal transmissions, providing timely synchronization checks while reducing unnecessary monitoring operations and system complexity

Inventive Principle:

Principle #19Periodic action

3Object-affected harmful factors

If terminals ignore uplink grant signals when time alignment is incorrect, then interference is reduced, but this causes resource wastage and requires additional random access procedures

Engineering Contradiction:

Improveinterference reductionVSAvoidrandom access procedure delay

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The terminal uses feedback from time alignment timer status to determine whether to process uplink grant signals. When the timer indicates incorrect timing, the terminal ignores the grant signal to prevent interference. Although this may require additional random access procedures, the feedback mechanism ensures that resources are not wasted on transmissions that would cause harmful interference

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10966185B2Method for transmitting and receiving signals in consideration of time alignment timer and user equipment for the same

Publication Date: 2021.03.30 LG ELECTRONICS INC

AI summary

A method for a user equipment (UE) to generate a transmission is provided. In this method, a UE starts a time alignment timer when a time alignment command is received. The UE receives an uplink grant; and generates an initial transmission or a retransmission according to the uplink grant only when the time alignment timer is running upon receiving the uplink grant. In addition, the uplink grant is received through a Physical Downlink Control Channel (PDCCH) indicated by a Cell Radio Network Temporary Identifier (C-RNTI) of the UE.