Synchronization Signal Block Transmission on Unlicensed Bands
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Solution Overview
Problem
In wireless communications systems operating on unlicensed frequency bands, there is a challenge in efficiently transmitting synchronization signal blocks to terminal devices, particularly in ensuring that multiple synchronization signal blocks are sent on available time-frequency resources without interfering with other devices, while maintaining synchronization and minimizing power consumption.
Innovation Solution
The method involves an access network device determining a resource set for transmitting a synchronization signal block set within a preset time window, using a combination of preset and flexible candidate resources, and performing clear channel assessment to ensure channels are idle before transmitting, thereby optimizing the transmission probability and reducing service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple synchronization signal blocks are transmitted on unlicensed frequency bands, then the transmission probability is improved, but the interference with other devices and channel contention increases
Solution Approach 1:
The access network device performs clear channel assessment (CCA) before transmitting synchronization signal blocks to determine if the channel is idle. This preliminary action prevents transmission on occupied channels, reducing interference with other devices while maintaining transmission probability on available channels.
Solution Approach 2:
The patent employs flexible candidate resources that can be dynamically adjusted based on channel conditions and traffic requirements. The resource set includes both preset resources and flexible resources that can be configured adaptively, allowing the system to optimize transmission probability while managing interference dynamically.
2Measurement precision
If terminal devices detect synchronization signals over longer time periods, then detection accuracy is improved, but power consumption increases
Solution Approach 1:
The access network device transmits synchronization signal blocks in concentrated time windows with specific periodicity. Terminal devices can perform detection within these defined time frames rather than continuously, achieving sufficient detection accuracy while significantly reducing power consumption by entering sleep modes between detection windows.
3Reliability
If synchronization signal blocks are transmitted frequently, then synchronization reliability is improved, but channel occupancy and interference increase
Solution Approach 1:
The patent implements periodic transmission of synchronization signal blocks within defined time windows at specific periodicity. This periodic action ensures synchronization reliability by maintaining regular transmission intervals while limiting overall channel occupancy, as transmissions are concentrated in specific periods rather than continuous occupation.
Solution Approach 2:
Clear channel assessment is performed before each synchronization signal block transmission to ensure the channel is idle. This preliminary check allows frequent transmission opportunities while actually occupying the channel only when necessary and safe, reducing overall interference and channel occupancy.
Data Source
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AI summary
This application discloses a synchronization signal block transmission method, an access network device, and a terminal device, so that an access network device in a wireless communications system operating on an unlicensed frequency band transmits a synchronization signal block to a terminal device. The method includes: determining, by an access network device, a resource set used for transmission of a synchronization signal block set in a preset time window, where the synchronization signal block set includes a first synchronization signal block and L second synchronization signal blocks, where L ≥ 1; the resource set includes a plurality of first candidate resources used to transmit the first synchronization signal block and at least L second candidate resources used to transmit the L second synchronization signal blocks; sending, by the access network device, the first synchronization signal block to a terminal device on a first resource in the plurality of first candidate resources based on a CCA result, and/or respectively sending N second synchronization signal blocks to the terminal device on N second resources; and determining, by the terminal device, time information based on the first synchronization signal block and/or the N second synchronization signal blocks.