Carrier Indicator for Synchronization Signal Transmission

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Solution Overview

Problem

In wireless communication networks, particularly in V2X sidelink communication scenarios, the simultaneous transmission of synchronization signals on multiple carriers during carrier aggregation leads to power reduction and half-duplex issues, while transmitting on a single synchronization carrier results in synchronization reference problems for legacy devices, especially in out-of-coverage scenarios.

Innovation Solution

The network node controls which carrier is used for transmitting synchronization signals, allowing for limited transmissions on a single carrier or aggregated carriers, ensuring backwards compatibility and optimizing performance by defining signaling conditions and criteria for SLSS transmission based on wireless device capabilities and modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If synchronization signals are transmitted simultaneously on multiple carriers during carrier aggregation, then synchronization coverage is improved, but power reduction and half-duplex issues occur

Engineering Contradiction:
Improvesynchronization coverageVSAvoidpower reduction
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent segments the synchronization signal transmission across different carriers by introducing a carrier indicator field that identifies which specific carrier should be used for SLSS transmission. This segmentation allows the system to maintain multiple carriers for data transmission while designating one specific carrier for synchronization purposes, thereby avoiding the power reduction issues of simultaneous multi-carrier synchronization transmission while preserving synchronization coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a network node as an intermediary that receives synchronization signal transmission indications from wireless devices and determines the appropriate carrier for SLSS transmission based on this indication. The network node acts as a mediator that coordinates between the device's synchronization needs and the carrier aggregation configuration, selecting the optimal carrier to avoid power reduction while maintaining synchronization coverage.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If synchronization signals are transmitted on a single synchronization carrier, then power reduction is avoided, but synchronization reference problems occur for legacy devices

Engineering Contradiction:
Improvepower reductionVSAvoidsynchronization reference for legacy devices
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent implements a universal carrier indication mechanism that works across both legacy and advanced wireless devices. The carrier indicator field in the synchronization signal transmission indication can be interpreted by all devices: legacy devices use it to identify the synchronization carrier for maintaining compatibility, while advanced devices with carrier aggregation capability use it in conjunction with their multi-carrier configuration. This multi-functional approach ensures that a single carrier transmission approach benefits all device types.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If carrier aggregation is used for V2X communication, then data rates and capacity are increased, but synchronization signal transmission becomes complex

Engineering Contradiction:
Improvedata ratesVSAvoidsynchronization signal transmission
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic carrier selection mechanism where the network node determines the appropriate carrier for SLSS transmission based on real-time conditions including the received synchronization signal transmission indication, carrier aggregation configuration, and network state. This dynamic approach allows the system to adapt the synchronization carrier selection to current operational requirements, simplifying the overall process by automating the decision-making rather than requiring complex static configurations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates feedback mechanisms where wireless devices provide synchronization signal transmission indications to the network node, which then uses this feedback to determine the appropriate carrier for SLSS transmission. This feedback loop allows the system to continuously optimize synchronization signal transmission based on actual device needs and network conditions, reducing complexity by using real-time information rather than relying on pre-configured complex synchronization schemes.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3777369B1A wireless device, a network node and methods therein for transmission of synchronization signals
Publication Date: 2023.08.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3777369B1 patent drawingFigure 1
  • EP3777369B1 patent drawingFigure 2
  • EP3777369B1 patent drawingFigure 3

AI summary

A method performed by a first wireless device (120) for transmitting a synchronization signal to a second wireless device (122). The first and second wireless devices (120,122)operate in a wireless communications network (100). The first wireless device (120)receives, from a network node (110) operating in the wireless communications network (100), a message indicating whether or not a carrier is to be used for transmitting a synchronization signal to the second wireless device (122). Further, the first wireless device (120) transmits, to the second wireless device (122), a synchronization signal on a carrier indicated by the received message.