Flexible Duplex Reference Signal Transmission

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Solution Overview

Problem

In LTE systems, the existing reference signal design fails to effectively reduce interference between uplink and downlink reference signals in neighboring cells, especially in flexible duplex systems where uplink and downlink traffic volumes vary, leading to severe interference in densely deployed small cells.

Innovation Solution

A method is introduced where base stations and user equipment dynamically configure reference signal transmission directions and timeslots based on traffic demands, using flexible frequency bands to minimize interference by configuring uplink and downlink transmissions differently between neighboring cells, and by making reference signals orthogonal to each other.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the existing reference signal design with fixed location and even distribution is used, then inter-cell interference can be reduced in traditional LTE systems, but severe interference occurs between uplink and downlink reference signals in flexible duplex systems

Engineering Contradiction:
Improveinterference between reference signalsVSAvoidadaptability to flexible duplex transmission
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the reference signal configuration adaptive to flexible duplex transmission. The base station determines target subframes based on uplink-downlink timeslot configurations and transmits reference signals dynamically configured according to traffic demands and transmission directions, allowing the system to adapt to changing conditions rather than using fixed patterns

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies local quality by configuring reference signals with cell-specific properties. Each base station determines target subframes and transmits reference signals with configurations tailored to its local uplink-downlink timeslot configuration and transmission direction, allowing neighboring cells to have different reference signal characteristics that reduce mutual interference

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If flexible duplex transmission is implemented to adapt to varying traffic volumes, then network adaptability is improved, but reference signal interference between neighboring cells increases

Engineering Contradiction:
Improveadaptability to traffic volume changesVSAvoidreference signal interference
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system maintains flexibility for traffic adaptation while dynamically determining target subframes based on uplink-downlink timeslot configurations. The base station transmits reference signals only in appropriate subframes where interference is minimized, allowing the system to adapt to traffic changes without suffering from constant interference

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameters of reference signal transmission by determining target subframes based on uplink-downlink timeslot configurations and transmission directions. By adjusting which subframes are used for reference signal transmission according to the flexible duplex configuration, the system maintains adaptability while reducing interference through parameter optimization

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If reference signals are transmitted in all subframes, then measurement accuracy is maintained, but interference from neighboring cells increases in flexible duplex systems

Engineering Contradiction:
Improvereference signal measurement accuracyVSAvoidinterference from neighboring cells
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts reference signal transmission from all subframes and confines it only to target subframes determined by uplink-downlink timeslot configurations. By removing reference signal transmission from subframes where it would cause or experience interference, the system maintains measurement accuracy in the remaining subframes while reducing overall interference

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the constraint of flexible duplex transmission, which causes interference, into a benefit by using the uplink-downlink timeslot configuration information to determine target subframes. The same configuration that causes interference also provides the knowledge needed to select subframes where reference signal transmission is beneficial and interference is minimized

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP3457774B1Method for transmitting reference signal
Publication Date: 2021.02.24 HUAWEI TECH CO LTD
  • EP3457774B1 patent drawingFigure 1~2
  • EP3457774B1 patent drawingFigure 3~5
  • EP3457774B1 patent drawingFigure 6~7

AI summary

A reference signal transmission method and a related device and system are disclosed. The method includes: determining, by a first base station, at least one target sub frame on a target frequency band, where the target frequency band is a frequency band whose uplink and downlink transmission directions are configurable, and uplink-downlink timeslot configurations and/or transmission directions of the first base station and a neighboring second base station in the at least one target subframe are different; and sending, by the first base station, a first reference signal to first user equipment UE in the at least one target subframe, where the first UE is UE served by the first base station. When embodiments of the present invention are implemented, a reference signal can be transmitted on a flexible frequency band, thereby effectively reducing interference between reference signals between neighboring cells in a flexible duplex system.