Downlink Control Information for SSB Position Indication
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Solution Overview
Problem
In 5G mobile communication systems, determining the position of Synchronizing Signal/PBCH Block (SSB) on unlicensed spectra is uncertain, posing a challenge for effective channel usage and data transmission.
Innovation Solution
A method and device for transmitting downlink control information that allows network devices to determine and indicate the position of SSB among multiple candidate positions, enabling terminal devices to accurately receive SSB positions and perform rate matching for data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple candidate SSB positions are configured on unlicensed spectrum, then the flexibility of SSB transmission is improved, but the uncertainty of SSB position determination worsens
Solution Approach 1:
The network device pre-configures multiple candidate SSB positions and transmits indication information in advance to indicate which candidate position is actually used. This preliminary indication resolves the position uncertainty before the terminal device attempts to receive SSB, allowing the terminal to directly access the correct position without blind detection across all candidates.
Solution Approach 2:
An indication mechanism serves as an intermediary between the network device and terminal device. The indication information (transmitted via PDCCH or PBCH) acts as a mediator that conveys the actual SSB position from the network to the terminal, resolving the information asymmetry and enabling the terminal to accurately determine the SSB position among multiple candidates.
2Reliability
If blind detection is used to determine SSB position, then the terminal device can handle position uncertainty, but the detection complexity and time consumption increase
Solution Approach 1:
The network device provides preliminary indication information about the actual SSB position before the terminal device performs detection. This advance information allows the terminal to skip blind detection across multiple candidate positions and directly access the indicated position, dramatically reducing detection time while maintaining reliable position acquisition.
3Ease of operation
If SSB transmission position is fixed, then the terminal device can easily determine the position, but the resource utilization efficiency on unlicensed spectrum decreases
Solution Approach 1:
The SSB transmission position transitions from a fixed value to a dynamic selection among multiple candidates. The network device can adaptively choose different candidate positions based on channel conditions and LBT results, improving resource utilization. The indication mechanism ensures that despite this dynamic behavior, the terminal can still easily determine the actual position through the received indication information.
Data Source
AI summary
The present application discloses a method and device for transmitting downlink control information, which may implement an effective transmission of an SSB on an unlicensed spectrum. The method includes: determining, by a network device, a first control resource set capable of being used by the network device among M control resource sets, where the M control resource sets correspond to Y candidate SSB positions on an unlicensed carrier; and sending, by the network device, first downlink control information on a resource of the first control resource set, where the first downlink control information is used to determine an SSB position where at least one SSB in X SSBs is sent among the Y SSB positions, where M, Y and X are all positive integers, and 1≤X<Y, M≤Y.