NCD-SSB Configuration for Small Data Transmission on Non-Cell-Defining Bandwidth Parts
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Solution Overview
Problem
Current 5G NR frameworks face challenges in supporting small data transmission (SDT) for RedCap UEs due to the absence of cell-defining synchronization signal blocks (CD-SSB) in bandwidth parts (BWP), leading to synchronization and timing accuracy issues during SDT procedures.
Innovation Solution
Configuring non-cell-defining synchronization signal blocks (NCD-SSBs) within BWP for RedCap UEs and non-RedCap UEs to enable efficient SDT procedures, allowing them to maintain timing alignment and perform reference signal measurements for determining the suitability and selection of SSBs for SDT, even in the absence of CD-SSB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a separate DL iBWP is configured for RedCap UEs without CD-SSB, then device complexity and power consumption are reduced, but DL synchronization and timing accuracy deteriorate
Solution Approach 1:
NCD-SSB serves as an intermediary element that provides synchronization functionality within the RedCap-specific BWP without requiring a full CD-SSB. The NCD-SSB acts as a mediator between the UE's need for synchronization and the network's desire to use a simplified BWP configuration, enabling the UE to maintain timing alignment and perform measurements using this intermediate synchronization signal.
Solution Approach 2:
The synchronization signal structure is adapted locally for the RedCap use case. Instead of using the full CD-SSB designed for general purposes, a customized NCD-SSB is created with specific properties tailored for RedCap UEs' synchronization needs within their constrained bandwidth, making the synchronization mechanism locally optimized rather than universally applied.
2Reliability
If UE monitors PDCCH for extended time during SDT procedure, then reliability of SDT is improved, but time resource utilization deteriorates
Solution Approach 1:
The NCD-SSB is configured and made available before the SDT procedure begins, allowing the UE to perform measurements and determine suitability in advance. This preliminary preparation enables the UE to make informed decisions about SDT initiation without requiring extended monitoring periods during the actual data transmission, thus reducing time resource utilization while maintaining reliability.
3Use of energy by moving object
If RedCap UEs use reduced bandwidth capabilities, then device footprint and power consumption are reduced, but communication capacity deteriorates
Solution Approach 1:
The system changes the parameters of the synchronization signal to match the reduced bandwidth capabilities of RedCap UEs. The NCD-SSB is configured with bandwidth and spectral characteristics that align with RedCap's reduced capabilities, allowing these devices to achieve synchronization and perform measurements effectively within their constrained bandwidth while maintaining reasonable communication capacity for their intended use cases.
Data Source
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AI summary
Various solutions for supporting small data transmission (SDT) on a bandwidth part (BWP) with non-cell-defining synchronization signal block (NCD-SSB) are described. An apparatus (310) may receive a configuration from a wireless node (320) of a wireless network. The configuration indicates one or more non-cell-defining synchronization signal blocks (NCD-SSBs) associated with a BWP for SDT. The apparatus (310) may initiate an SDT procedure on the BWP according to the configuration.