SS-Block Configuration for 5G NR Unlicensed Spectrum Channel Access
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Solution Overview
Problem
The existing synchronization signal block (SS-block) configurations are not applicable for the 5G New Radio (NR) unlicensed spectrum due to excessively long transmission durations, which fail to meet the demands of increasing mobile communication services.
Innovation Solution
A method for configuring the SS-block in the NR unlicensed spectrum, where the SS-block occupies a variable number of Orthogonal Frequency Division Multiplexing (OFDM) symbols (x, where x is a positive integer no greater than 4) and is transmitted with a preset or configured subcarrier spacing, allowing for efficient transmission of Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), and Physical Broadcast Channel (PBCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SS-block uses traditional configuration in unlicensed spectrum, then synchronization and broadcast functions are provided, but the transmission duration is excessively long which reduces channel utilization efficiency
Solution Approach 1:
The SS-block is segmented into multiple parts transmitted in different beams during beam sweeping. Each SS-block contains PSS, SSS, and PBCH that can be transmitted in a compressed manner (e.g., PSS and SSS in one OFDM symbol, PBCH in another symbol), allowing the complete synchronization information to be delivered through multiple shorter transmissions rather than one long transmission, thus reducing the duration each SS-block occupies the channel while maintaining reliable synchronization.
Solution Approach 2:
The system employs periodic beam sweeping where SS-blocks are transmitted in repeated cycles across different beams. Instead of transmitting all synchronization information in one continuous long SS-block, the transmission is broken into periodic shorter SS-blocks that sweep through different beams, achieving both coverage and reduced channel occupation time per SS-block.
2Loss of information
If the SS-block occupies more OFDM symbols to ensure complete transmission of PSS, SSS, and PBCH, then the synchronization information is complete, but the duty cycle of discovery reference signal increases reducing overall system capacity
Solution Approach 1:
The synchronization information is segmented across multiple shorter SS-blocks transmitted in different beams. Each SS-block contains essential synchronization elements (PSS, SSS, PBCH) compressed into fewer OFDM symbols. The completeness is achieved through the collective information from multiple beam sweeps rather than requiring all information in one long SS-block, thus maintaining information completeness while reducing individual SS-block duration and increasing system capacity.
Solution Approach 2:
The system dynamically adapts SS-block configuration based on beam sweeping requirements. SS-blocks are configured with flexible parameters (subcarrier spacing, cyclic prefix length, number of OFDM symbols) that can be adjusted to optimize the balance between information completeness and transmission efficiency, allowing the system to maintain capacity while ensuring complete synchronization information delivery.
3Adaptability or versatility
If the SS-block transmission duration is extended to accommodate beam sweeping process, then beam coverage is improved, but the channel occupation time increases reducing unlicensed spectrum efficiency
Solution Approach 1:
The beam sweeping process is segmented into multiple independent SS-block transmissions, each covering a specific beam direction. Instead of extending one SS-block to cover all beams, the system transmits shorter SS-blocks sequentially in different beams, achieving comprehensive coverage through spatial segmentation rather than temporal extension, thus maintaining beam coverage while minimizing channel occupation time.
Solution Approach 2:
The system uses periodic beam sweeping with SS-blocks transmitted in repeated cycles across different beam directions. Each SS-block in the sweep has a short duration, but the periodic repetition across multiple beams achieves comprehensive coverage. This periodic approach allows the channel to be released between sweeps, reducing overall channel occupation time while maintaining adaptability and coverage.
Data Source
AI summary
Provided is a method and device for transmitting and receiving a Synchronization Signal block (SS-block). The method for transmitting the SS-block includes: configuring the SS-block in an NR unlicensed spectrum, wherein the SS-block occupies x OFDM symbols, with x being a positive integer no greater than 4; and transmitting the S S-block to a user equipment with a preset or configured subcarrier spacing. By this method, during the configuration of SS-block, the SS-block occupies x Orthogonal Frequency Division Multiplexing symbols. If the SS-block occupies a relatively small number of symbols, it is possible to reduce the duty cycle of DRS. In other words, it is possible to shorten the transmission duration of the SS-block, so as to reduce the time that the SS-block occupies the channel in the unlicensed spectrum.