SSB-Based Cell Selection for Initial Access on Shared Downlink Carriers
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Solution Overview
Problem
In wireless communication systems with shared downlink carriers, user equipment (UE) faces challenges in selecting the appropriate cell for initial access due to a lack of clear signaling for random access, especially when multiple cells share a common set of resources, leading to confusion about which cell to select for communication.
Innovation Solution
The UE receives a set of synchronization signal blocks (SSBs) from a single cell or multiple cells, which include master information blocks (MIBs) and scheduling system information blocks (SIBs) to facilitate cell selection and perform initial access or random access procedures, while network nodes transmit SSBs using muting or puncturing techniques without modifying the MIB or SIB payload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cells share a common downlink carrier, then system resource utilization is improved, but cell selection complexity increases
Solution Approach 1:
The patent segments the downlink carrier into multiple time slots, where each time slot is dedicated to a specific cell for SSB transmission. This temporal segmentation allows multiple cells to share the same frequency carrier while maintaining distinct signaling opportunities, thereby enabling cell selection without excessive complexity.
Solution Approach 2:
The patent implements preliminary action by having network nodes transmit SSBs in advance during designated time slots before the UE needs to perform cell selection. The UE receives and stores these SSBs (including MIB and SIB information) before making its cell selection decision, simplifying the overall selection process.
2Area of stationary object
If SSBs are transmitted on shared downlink carrier, then downlink coverage is improved, but random access signaling clarity deteriorates
Solution Approach 1:
The patent segments the random access signaling process into two distinct phases: (1) SSB transmission phase where network nodes broadcast MIB and SIB information on shared downlink carriers, and (2) Random access procedure phase where UE selects a cell and transmits access messages on uplink carriers. This segmentation maintains signaling clarity despite carrier sharing.
Solution Approach 2:
The patent uses SSBs as an intermediary carrier for initial downlink communication. The SSBs carry MIB and SIB information that mediates between the shared downlink carrier and the UE's cell selection process, providing clear signaling without requiring dedicated random access channels on the shared carrier.
3Productivity
If network nodes transmit SSBs on shared carrier, then spectral efficiency is improved, but UE processing complexity increases
Solution Approach 1:
The patent segments the SSB transmission in time, assigning specific time slots to specific cells. This allows the UE to receive SSBs from multiple cells on the shared carrier during different time slots, reducing the processing complexity by organizing the reception process temporally rather than requiring simultaneous processing of all cells.
Solution Approach 2:
The patent implements preliminary action by having network nodes transmit complete SSB information (MIB and SIB) in advance during designated time slots. The UE can then process and store this information before making cell selection decisions, distributing the processing load in time rather than requiring all processing to occur simultaneously.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, for a cell group with a shared downlink carrier, at least one downlink communication conveying a set of synchronization signal blocks (SSBs) for a set of cells of the cell group. The UE may transmit, for a cell of the cell group, an initial access message based on an SSB of the set of SSBs. Numerous other aspects are described.