MBS PDCCH-SSB Mapping for Reliable Beam-Swept Reception
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Solution Overview
Problem
In the NR system, efficiently transmitting broadcast MBS services in RRC idle, inactive, or connected states is challenging due to the need for beam sweeping and the lack of clear association between PDCCH opportunities and SSB indices, leading to potential service interruptions and reception errors.
Innovation Solution
A method and apparatus that determine a correspondence between PDCCH opportunities and SSB indices to facilitate accurate reception of MBS PDCCH, using a new SIB to configure MCCH and MTCH channels, and employing specific indexing methods to number PDCCH opportunities within defined time windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam sweeping is used to transmit broadcast MBS service, then coverage and service availability are improved, but the complexity of associating PDCCH opportunities with SSB indices increases and reception reliability deteriorates
Solution Approach 1:
The network device pre-configures the correspondence between PDCCH opportunities and SSB indices through higher layer signaling (e.g., SIB1 or dedicated RRC signaling) before actual MBS service transmission. This preliminary configuration enables terminal devices to know in advance which PDCCH opportunities to monitor for which SSB indices, eliminating the need for complex real-time association and reducing reception errors.
2Area of stationary object
If beam sweeping is used to transmit broadcast MBS service, then coverage is improved, but reception accuracy deteriorates due to lack of clear PDCCH-SSB association
Solution Approach 1:
Higher layer signaling (SIB1 or dedicated RRC signaling) acts as an intermediary to convey the PDCCH-SSB association information from the network device to terminal devices. This intermediary mechanism ensures that terminal devices receive accurate association information without having to perform complex measurements or calculations, thereby improving reception accuracy while maintaining wide coverage.
3Ease of operation
If PDCCH opportunities are monitored without clear SSB index association, then terminal devices can operate in RRC idle state, but service interruptions increase
Solution Approach 1:
The network device provides preliminary configuration of PDCCH monitoring opportunities and their corresponding SSB indices through higher layer signaling before the terminal device needs to receive MBS service. This allows terminal devices in RRC idle state to know in advance which PDCCH opportunities to monitor, ensuring continuous service reception without interruptions while maintaining operational simplicity.
Data Source
AI summary
Provided in the embodiments of the present application are a method and apparatus for transmitting an MBS service, and a terminal device. The method comprises: a terminal device determines a correspondence between a physical downlink control channel (PDCCH) occasion and a synchronization signal block (SSB) index, wherein the PDCCH occasion is used for transmitting an MBS PDCCH; and the terminal device receives the MBS PDCCH on the basis of the correspondence between the PDCCH occasion and the SSB index.