Uplink Signal Transmission Timing Alignment in LAA

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Solution Overview

Problem

In LAA systems, uplink synchronization delays occur due to channel occupancy by other systems like WiFi, leading to mutual interference and inefficient network performance.

Innovation Solution

The method involves scheduling uplink signals based on either downlink (DL) timing or uplink (UL) timing, with a transmission timing offset, allowing UEs to perform CCA detection and transmission accordingly, ensuring simultaneous transmission without interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UEs perform CCA detection independently based on their own timing, then each UE can detect channel availability, but transmission times become unsynchronized causing mutual interference

Engineering Contradiction:

Improvechannel detection reliabilityVSAvoidmutual interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies equipotentiality by aligning all UEs to a common reference timing (DL timing or UL timing) so that they perform CCA detection and transmit uplink signals at the same absolute time. This eliminates the timing differences between UEs that cause mutual interference, while maintaining each UE's ability to independently detect channel availability through CCA.

Inventive Principle:

Principle #12Equipotentiality

2Ease of operation

If UEs transmit uplink signals at different times due to timing advances, then individual UE timing can be optimized, but uplink synchronization delays increase

Engineering Contradiction:

Improvetiming optimizationVSAvoidsynchronization delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent introduces a common reference timing (either DL timing from the base station or a unified UL timing) as an intermediary that mediates between individual UE timing requirements. Each UE calculates its transmission time based on this common reference, ensuring that despite different propagation delays, all UEs transmit at synchronized absolute times, thereby reducing uplink synchronization delays.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If LAA systems use unlicensed frequency bands to supplement licensed bands, then spectrum utilization improves, but interference from other wireless systems increases

Engineering Contradiction:

Improvespectrum utilizationVSAvoidinterference from other systems

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by requiring UEs to perform CCA detection before transmitting uplink signals on unlicensed frequency bands. This preliminary channel assessment ensures that UEs only transmit when the channel is idle, preventing interference with other wireless systems like WiFi and radar, while still allowing LAA to utilize unlicensed spectrum resources.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3989668B1Method and user equipment for transmitting uplink signals

Publication Date: 2024.04.17 SAMSUNG ELECTRONICS CO LTD

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AI summary

The present disclosure provides an uplink signal transmission method, user equipment (UE) and base station. When the UE transmits uplink signals in an unlicensed frequency band after receiving uplink synchronization command information, the UE transmits one or more uplink signals according to a predefined time or a time indicated by the base station. The UE determines mapping of an uplink signal according to the predefined time or the indicated time. When provided with the present disclosure, interference between signals of a same type or between signals of different types can be reduced and a signal transmission probability can be improved accordingly.