Synchronization Mechanism for Unlicensed Band Carrier Aggregation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In LTE-Advanced systems, maintaining synchronization on unlicensed bands is challenging due to frequent interruptions from co-existing systems like WiFi, leading to delays in time and frequency synchronization, especially in scenarios with multiple carriers and repeaters/RRHs, which affects data throughput and latency.

Innovation Solution

The method involves determining the off-duration of a shared carrier aggregation channel and performing fine synchronization using CRS tracking with course synchronization parameters from the previous ON period if the off-duration is below a threshold, and resorting to coarse synchronization on other carriers if the off-duration exceeds a maximum threshold, utilizing a Fast Synchronization Verification Block (FSVB) for rapid and reliable synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fine synchronization based on CRS tracking is performed continuously on the SCC channel, then synchronization precision is improved, but energy consumption increases and spectrum sharing capability deteriorates

Engineering Contradiction:

Improvesynchronization precisionVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic synchronization by determining the off-duration of the SCC channel and selectively performing fine synchronization only when the off-duration is below a threshold. This periodic approach replaces continuous CRS tracking, reducing energy consumption while maintaining synchronization precision when needed.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts the synchronization strategy based on the off-duration condition. When off-duration is short, fine synchronization is performed; when off-duration is long, coarse synchronization is used. This dynamic adaptation optimizes energy consumption while maintaining adequate synchronization precision.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If fine synchronization based on CRS tracking is performed continuously on the SCC channel, then synchronization precision is improved, but the system's adaptability to spectrum sharing deteriorates

Engineering Contradiction:

Improvesynchronization precisionVSAvoidspectrum sharing capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If coarse synchronization is performed on other carriers when off-duration exceeds maximum threshold, then adaptability to spectrum sharing is improved, but synchronization precision deteriorates

Engineering Contradiction:

Improvespectrum sharing capabilityVSAvoidsynchronization precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses coarse synchronization parameters obtained from previous ON periods as a buffer or cushion. These pre-obtained parameters allow the system to quickly resume fine synchronization after a long off-duration, reducing the precision loss associated with using only coarse synchronization.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Productivity

If the system allows frequent interruptions for spectrum sharing with other networks, then spectrum utilization is improved, but synchronization stability deteriorates

Engineering Contradiction:

Improvespectrum utilizationVSAvoidsynchronization stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent performs coarse synchronization and obtains synchronization parameters during ON periods in advance. These pre-obtained parameters serve as a foundation that maintains synchronization stability during OFF periods when the channel is shared with other networks, allowing frequent spectrum sharing without compromising stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the off-duration is continuously monitored and used to determine the appropriate synchronization strategy. This feedback loop allows the system to adapt to frequent interruptions while maintaining synchronization stability by switching between fine and coarse synchronization based on actual channel conditions.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9603025B2Method and apparatus for synchronization mechanisms on un-licensed band

Publication Date: 2017.03.21 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A method for synchronizing channels on unlicensed bands is described. The method includes determining whether a SCC channel has started to be used by a first network. The SCC channel is a CA channel shared with at least one other network. In response to determining that the SCC channel has been started to be used by the first network, the UE determines an off duration describing a period since a previous SCC channel ON period. A given channel ON period is a continuous period of use of the given channel by the first network, The method also includes, in response to determining that the off duration is less than a minimum threshold duration, performing fine synchronization based on CRS tracking on the SCC channel using course synchronization parameters of the previous SCC channel ON period. Apparatus and computer readable media are also described.