Synchronization Signal Sub-Raster for Narrowband UE Cell Search
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Solution Overview
Problem
Existing wireless communication systems face synchronization inefficiencies and delays due to the inability to account for varying UE operating bandwidths, particularly when UEs operate with bandwidths less than synchronization signal bandwidths, leading to incomplete capture of synchronization signals during cell acquisition.
Innovation Solution
Implementing a sub-raster rastering technique for UEs to enhance synchronization signal capture, along with supplementary narrowband synchronization signals and partially decodable wideband synchronization signals, allowing UEs to perform cell search on overlapping subbands and ensuring partial correlation/decodability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If base station transmits synchronization signal using wideband configuration, then synchronization signal can be received by wideband UEs, but narrowband UEs cannot properly receive or synchronize due to bandwidth mismatch
Solution Approach 1:
The synchronization signal is divided into multiple subbands, each transmitted with independent synchronization information. This allows narrowband UEs to receive and process only the subband portion relevant to their operating bandwidth, while wideband UEs can receive multiple subbands. The segmentation enables the single synchronization signal transmission to serve both narrowband and wideband UEs simultaneously without requiring separate transmissions.
2Ease of manufacture
If base station uses fixed synchronization signal bandwidth, then signal transmission is simplified, but UEs with different operating bandwidths experience synchronization inefficiencies and delays
Solution Approach 1:
The synchronization signal transmission adapts dynamically to UE bandwidth requirements by configuring different subband combinations based on UE capability information. The base station determines which subbands to transmit based on whether the UE is narrowband or wideband, enabling optimized synchronization performance for each UE type without requiring completely different fixed transmission schemes.
3Loss of information
If base station transmits full bandwidth synchronization signal, then wideband UEs receive complete information, but narrowband UEs must filter out irrelevant portions causing processing delay
Solution Approach 1:
By segmenting the synchronization signal into multiple subbands with independent synchronization information, each subband can be optimally processed by narrowband UEs without requiring them to filter through irrelevant portions of a full-bandwidth signal. This reduces processing time and enables faster cell search for narrowband UEs while maintaining complete synchronization information availability.
Data Source
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Figure 3A~3B
AI summary
A base station may identify that a user equipment (UE) supports operation within a UE bandwidth that is less than a synchronization signal bandwidth used by a wireless network to transmit a synchronization signal. The base station may then generate a synchronization signal raster (e.g., sub-raster) based at least in part on the UE bandwidth being less than the synchronization signal bandwidth. The raster may ensure portions or specific sections (e.g., subbands) of the synchronization signal are captured by the narrowband UE. In some cases, the base station may configure or modify a synchronization signal based at least in part on wireless network support of narrowband UE operation. For example, supplementary narrowband synchronization signals transmitted over additional time and/or frequency resources, partially decodable wideband synchronization signals designed to allow partial correlation/decoding by narrowband UEs, or concatenated synchronization signal segments (e.g., in frequency) may be employed.