SS/PBCH Point A Alignment for Punctured Narrowband NR Reception
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Solution Overview
Problem
The determination of Point A, a common reference point for resource block grids, is unclear when SSBs are punctured, especially for UEs supporting channel bandwidths less than 5 MHz, leading to uncertainty in frequency resource allocation.
Innovation Solution
A method for determining Point A based on the frequency offset between the lowest subcarrier of the lowest resource block overlapping with the SS/PBCH block after puncturing, using configuration information to define the SS/PBCH block structure and resource block grids, enabling reliable frequency resource allocation for narrowband UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the maximum bandwidth is reduced to support narrowband UEs, then device complexity and cost are reduced, but the ability to receive the entire SSB is lost
Solution Approach 1:
The SSB reception process is segmented into two parts: the full SSB transmitted by the base station and the punctured SSB received by narrowband UEs. The resource blocks are divided such that CRBs 0-11 contain the SS/PBCH block while CRBs 12-19 are punctured for narrowband operation, allowing UEs to receive the necessary synchronization signals within their bandwidth constraints.
Solution Approach 2:
Different quality requirements are applied to different parts of the frequency spectrum. The resource blocks containing the SS/PBCH block (CRBs 0-11) maintain full quality for synchronization, while other resource blocks (CRBs 12-19) are punctured or reduced in quality, allowing narrowband UEs to focus resources on critical signaling while ignoring non-essential portions.
2Adaptability or versatility
If puncturing is performed on SSB resources, then narrowband UE support is enabled, but the determination of Point A becomes unclear
Solution Approach 1:
The definition of Point A is predetermined and established before puncturing occurs. Point A is defined as the common reference point corresponding to the lowest subcarrier of the lowest resource block that overlaps with the SS/PBCH block in the frequency domain. This preliminary definition ensures that even after puncturing, the reference point remains clearly identifiable for resource block grid alignment.
Solution Approach 2:
The SS/PBCH block serves as an intermediary that bridges the full-bandwidth transmission and narrowband reception. By defining Point A based on the SS/PBCH block's resource block overlap, the system creates a stable reference that mediates between the punctured resource structure and the UE's need for consistent frequency alignment.
3Adaptability or versatility
If the SSB is transmitted in a punctured resource region, then narrowband channel support is achieved, but frequency resource allocation becomes uncertain
Solution Approach 1:
The resource block grid is aligned to a common reference point (Point A) that creates equipotential conditions across different bandwidth configurations. By defining all resource blocks relative to this common reference, the system ensures that frequency resource allocation maintains consistent precision whether the UE operates in wideband or narrowband mode, eliminating allocation uncertainty.
Data Source
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AI summary
A method performed by a user equipment (UE) according to an embodiment of the present disclosure comprises receiving a Synchronization Signal/Physical Broadcast CHannel (SS/PBCH) block, and receiving configuration information including information related to a Point A. Based on the information related to the Point A, a frequency offset between i) the Point A and ii) a lowest subcarrier of a lowest resource block overlapping with the SS/PBCH block is determined. The lowest subcarrier of the lowest resource block overlaps with the SS/PBCH block after puncturing.