Initial Access Beam Sweeping With Wide-to-Narrow Beam Selection
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Solution Overview
Problem
Existing beam sweeping techniques in wireless communications systems, particularly in high-frequency systems like 5G/NR, involve lengthy processes that increase signaling overhead due to the use of numerous narrow beams, which reduces efficiency.
Innovation Solution
The base station reduces the number of beams used for sweeping by employing a smaller number of wide beams over azimuth and elevation directions, and the UE reports the selected narrow beam pair using synchronization signal blocks (SSBs) on random access channel (RACH) occasions, allowing for efficient beam selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerous narrow beams are used for beam sweeping, then beam selection precision is improved, but signaling overhead increases and process length increases
Solution Approach 1:
The beam sweeping process is segmented into two distinct phases: a first beam sweep using wide beams for coarse directional identification, and a second beam sweep using narrow beams for precise beam selection. This segmentation allows the system to achieve high measurement precision in the second phase while limiting signaling overhead in the first phase by using fewer, wider beams for initial direction finding.
Solution Approach 2:
The first beam sweep using wide beams serves as a preliminary action that identifies coarse directional information before the second beam sweep. This preliminary identification narrows down the search space for the subsequent narrow beam sweep, reducing the number of narrow beams needed and thereby reducing overall signaling overhead while maintaining beam selection precision.
2Measurement precision
If numerous narrow beams are used for beam sweeping, then beam selection precision is improved, but process duration increases
Solution Approach 1:
The beam sweeping process is divided into two sequential phases with distinct purposes: the first phase uses wide beams to quickly identify coarse directions, and the second phase uses narrow beams for precise beam selection. This segmentation reduces the total number of narrow beams required, thereby shortening the overall beam sweeping duration while maintaining beam selection precision.
Solution Approach 2:
The first beam sweep with wide beams performs a preliminary directional identification that narrows down the search space before the second beam sweep. This preliminary action reduces the number of narrow beams needed in the second phase, thereby reducing the total beam sweeping duration while achieving the required beam selection precision.
3Loss of information
If wide beams are used for beam sweeping, then signaling overhead is reduced, but beam selection precision deteriorates
Solution Approach 1:
The system segments the beam sweeping function into two phases: the first phase uses wide beams for coarse directional identification with lower signaling overhead, and the second phase uses narrow beams for precise beam selection. This segmentation allows wide beams to reduce signaling overhead while narrow beams restore beam selection precision in the final stage.
Solution Approach 2:
The first beam sweep with wide beams performs a preliminary identification of coarse directions, which reduces the search space for the second beam sweep. This preliminary action allows the system to use fewer narrow beams in the second phase, thereby reducing signaling overhead while maintaining the precision needed for final beam selection.
4Duration of action of moving object
If wide beams are used for beam sweeping, then beam sweeping duration is reduced, but beam selection precision deteriorates
Solution Approach 1:
The beam sweeping process is segmented into two phases: the first phase uses wide beams for quick coarse directional identification, and the second phase uses narrow beams for precise beam selection. This segmentation reduces the total beam sweeping duration by using wide beams first, while the second phase with narrow beams ensures beam selection precision is achieved.
Solution Approach 2:
The first beam sweep with wide beams performs a preliminary directional identification that quickly narrows down the search space. This preliminary action reduces the overall beam sweeping duration, and the subsequent second beam sweep with narrow beams ensures that beam selection precision is achieved with fewer iterations.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a user equipment (UE) may receive a system information message from a base station indicating a beam sweeping procedure supported by the base station. Based on the system information message, the UE may receive, as part of the indicated beam sweeping procedure, a first synchronization signal block (SSB) as part of first set of SSBs, and a second SSB as part of a second set of SSBs. The UE may then transmit, to the base station, one or more messages that indicate a narrow beam for communications between the UE and the base station. In some cases, the indicated beam may correspond to the first SSB and the second SSB, and is indicated on one or more random access channel (RACH) occasions associated with the beam sweeping procedure.