Air Interface Synchronization in High-Density Small Cell Networks

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Solution Overview

Problem

In high-density small cell deployments of LTE/LTE-A mobile communication systems, the switching off of a source eNB can lead to loss of air interface synchronization for target eNBs, as they cannot detect normal synchronization reference signals, affecting system performance and energy efficiency.

Innovation Solution

Implementing a method where the source cell performs signaling interaction with the target cell to determine whether to switch off, and notifies adjacent cells of its monitoring sub-frame position for air interface synchronization, allowing for muting and ensuring that the target cell can find a new synchronization source before the source cell enters an off state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the source cell is switched off to save energy, then energy consumption is reduced, but air interface synchronization for the target cell is lost

Engineering Contradiction:

Improveenergy consumptionVSAvoidair interface synchronization

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The source cell performs signaling interaction with the target cell before switching off to determine whether it can be switched off. This preliminary check ensures that the target cell has alternative synchronization sources or can tolerate the source cell being off, thereby maintaining synchronization reliability while enabling energy saving.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the target cell provides information about its synchronization status and alternative sources to the source cell. This feedback allows the source cell to make informed decisions about switching off, ensuring that energy saving actions do not compromise synchronization reliability.

Inventive Principle:

Principle #23Feedback

2Loss of energy

If the source cell switches off without notification, then energy saving is achieved, but the target cell cannot detect synchronization reference signals

Engineering Contradiction:

Improveenergy consumptionVSAvoidsynchronization reference signal

Core Design Contradiction:

Loss of energyVSLoss of information

Solution Approach 1:

Before the source cell switches off, it performs signaling interaction with the target cell to notify it of the upcoming shutdown. This preliminary notification allows the target cell to prepare for the loss of synchronization signals, either by switching to alternative sources or by adjusting its monitoring behavior, thus preventing information loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The source cell takes preliminary actions to prevent the harmful effect of synchronization signal loss by notifying the target cell in advance and coordinating the shutdown timing. This anti-action ensures that the target cell is prepared and can maintain synchronization through alternative means.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If signaling interaction is implemented between source and target cells, then synchronization reliability is maintained during switching, but system complexity increases

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and formalizes the signaling interaction protocol into standardized procedures and messages. By defining specific signaling formats and interaction patterns, the complexity is managed and contained within well-defined interfaces, making the system easier to implement and maintain despite the added reliability mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

4Loss of energy

If the source cell enters off state without coordination, then energy saving is achieved, but adjacent cells' synchronization is influenced

Engineering Contradiction:

Improveenergy consumptionVSAvoidinterference to adjacent cells

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The source cell performs preliminary signaling interaction with adjacent cells before switching off, notifying them of the upcoming shutdown. This allows adjacent cells to adjust their synchronization strategies in advance, preventing harmful effects on their synchronization performance while still enabling the source cell to save energy.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system implements feedback mechanisms where adjacent cells provide information about their synchronization dependencies on the source cell. This feedback allows the source cell to coordinate its shutdown timing and manner to minimize interference with adjacent cells, balancing energy saving with harm reduction.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10791528B2Method, cell and system for implementing air interface synchronization

Publication Date: 2020.09.29 ZTE CORP

AI summary

Disclosed is a method for implementing air interface synchronization. The method includes that: a source cell performs signalling interaction with a target cell, and determines whether to be switched off or not according to a signalling interaction result. A content about which the source cell performs signalling interaction with the target cell includes at least one of: on/off state information of the source cell, on/off state information of the target cell, whether the target cell finds a new synchronization source or not, timing at which the source cell enters an off state, candidate synchronization source cell set information of the target cell and associated affiliated target cell information of the target cell. The present disclosure further discloses a cell and system for implementing air interface synchronization.