SSB Configuration for Reduced-Bandwidth MTC UE Synchronization
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Solution Overview
Problem
MTC UEs with reduced capabilities are unable to receive and decode synchronization signal blocks (SSBs) formatted for more capable devices due to bandwidth limitations, preventing effective communication in 5G networks.
Innovation Solution
The SSB is formatted to allow MTC UEs to detect and receive SSBs by monitoring PRBs above and below a synchronization raster point, duplicating and conjugating PSS and SSS across multiple symbols, and adjusting PBCH transmission to compensate for reduced capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SSB is formatted for more capable devices with wider bandwidth, then synchronization signal quality and coverage are improved, but MTC UEs with reduced capabilities cannot receive and decode the SSB
Solution Approach 1:
The SSB monitoring resources are segmented into two separate occasions: first SSB occasion for monitoring PRBs above the center frequency and second SSB occasion for monitoring PRBs below the center frequency. This segmentation allows MTC UEs to receive synchronization signals in a bandwidth manner compatible with their reduced capabilities while maintaining synchronization signal quality
Solution Approach 2:
The patent introduces a time dimension by using multiple SSB occasions instead of relying solely on frequency diversity within a single occasion. MTC UEs can accumulate synchronization signals across multiple time instances, effectively trading time for frequency resources to overcome bandwidth limitations
2Measurement precision
If SSB monitoring uses a large number of PRBs to ensure coverage, then synchronization accuracy is improved, but MTC UEs with bandwidth limitations cannot monitor all required PRBs
Solution Approach 1:
The monitoring bandwidth is segmented into multiple PRB sets across different SSB occasions. Instead of requiring MTC UEs to monitor all PRBs simultaneously within a single occasion, the same PRBs are monitored across multiple occasions, allowing UEs to accumulate synchronization information within their limited instantaneous bandwidth
Solution Approach 2:
The network pre-configures the SSB monitoring pattern and PRB allocation for MTC UEs before actual synchronization. This allows UEs to know in advance which PRBs to monitor during each occasion, optimizing their limited bandwidth usage while ensuring they can accumulate sufficient synchronization information over time
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A machine-type-communication (MTC) UE may monitor for a synchronization signal block (SSB) from a network entity. The SSB may be formatted in accordance with a capability of the MTC UE such that the MTC UE may receive the SSB. In some examples, the MTC UE may receive the SSB within a quantity of physical resource blocks (PRBs) supported by the MTC UE. The SSB may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). To account for the capability of the MTC UE, the network entity may transmit the PSS and the SSS over two symbols, where each symbol includes a portion of the PSS or the SSS in accordance with the capability of the MTC UE.