CSI-RS Transmission Timing in Unlicensed LTE

Solution Overview

Problem

In licensed-assisted access using Long Term Evolution (LAA-LTE) systems, channel state information reference signals (CSI-RS) are either transmitted too late due to random timing or require high signaling overheads when sent aperiodically, hindering timely channel state information acquisition for user equipment (UE).

Innovation Solution

The method involves pre-configuring multiple groups of CSI-RS with different sending periods and offsets, allowing the transmit end device to select and send the target CSI-RS at its start sending moment after obtaining an unlicensed carrier, thereby reducing signaling overheads and ensuring timely transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If CSI-RS is periodically transmitted with random preemption timing, then the eNB can obtain the channel by means of preemption at a random moment, but the CSI-RS cannot be sent to the UE in time and the UE cannot obtain channel state information in time

Engineering Contradiction:

Improveflexibility in channel preemption timingVSAvoiddelay in channel state information acquisition

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent pre-configures multiple groups of CSI-RS resources with different periodicities and time offsets before actual transmission. When the eNB preempts the channel, it can immediately select the most appropriate pre-configured CSI-RS group without requiring real-time configuration decisions, thus eliminating timing delays while maintaining flexibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables dynamic selection among multiple pre-configured CSI-RS groups based on actual channel conditions and timing requirements. The system can adaptively choose different CSI-RS transmission patterns (different periodicities and offsets) to match the random preemption timing, ensuring timely channel state information delivery while maintaining operational flexibility.

Inventive Principle:

Principle #15Dynamics

2Loss of time

If CSI-RS is aperiodically transmitted, then the eNB can send CSI-RS when needed, but the eNB needs to frequently send signaling to the UE to indicate a location for sending the CSI-RS each time, and signaling overheads are relatively high

Engineering Contradiction:

Improvetimeliness of CSI-RS transmissionVSAvoidsignaling overhead

Core Design Contradiction:

Loss of timeVSLoss of information

Solution Approach 1:

The patent pre-configures multiple groups of CSI-RS resources with different periodicities and time offsets before actual transmission. When the eNB preempts the channel, it can immediately select the most appropriate pre-configured CSI-RS group without requiring real-time configuration decisions, thus eliminating timing delays while maintaining flexibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent divides CSI-RS resources into multiple pre-configured groups with different characteristics (periodicities and offsets). This segmentation allows the system to select the most appropriate group for each specific transmission opportunity, avoiding the need for frequent full-reconfiguration signaling while maintaining aperiodic transmission flexibility.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If a single group of CSI-RS is configured, then the configuration is simple, but the CSI-RS cannot be flexibly sent to the UE at the optimal timing after channel preemption

Engineering Contradiction:

ImproveCSI-RS configuration complexityVSAvoidflexibility in CSI-RS transmission timing

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent pre-configures multiple groups of CSI-RS resources with different periodicities and time offsets before actual transmission. When the eNB preempts the channel, it can immediately select the most appropriate pre-configured CSI-RS group without requiring real-time configuration decisions, thus eliminating timing delays while maintaining flexibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a multi-functional CSI-RS configuration system where multiple pre-configured groups serve different timing scenarios. This universal configuration approach allows a single set of pre-configured resources to handle various preemption timing situations, providing flexibility without proportionally increasing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3267643B1Efficient transmission and reception of channel state information reference signals

Publication Date: 2019.09.18 HUAWEI TECH CO LTD

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AI summary

Embodiments of the present invention provide a method and device for transmitting a channel state information reference signal CSI-RS. The method includes: obtaining, by a first device, an unlicensed carrier; determining, by the first device, a target CSI-RS from M pre-configured groups of CSI-RSs, where each group of CSI-RSs in the M groups of CSI-RSs are periodically sent in a time domain, different groups of CSI-RSs in the M groups of CSI-RSs have different sending periods and/or offsets, and M is an integer greater than 1; and sending, by the first device, the target CSI-RS to a second device based on the unlicensed carrier at a start sending moment of the target CSI-RS. According to the method and device for transmitting a CSI-RS provided in the embodiments of the present invention, a sending location (that is a sending moment) can be flexibly selected to send the CSI-RS to a receive end device, without requiring high signaling overheads.