PBCH-Based Receive Beam Refinement for Faster 5G Cell Search
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Solution Overview
Problem
Current beam refinement methods in wireless communication systems, particularly in 5G NR, face challenges such as increased latency and power consumption during initial cell search procedures, especially in millimeter wave (mmW) systems, due to the need to scan multiple refined receive beam directions, which can prolong RF open time and increase power usage.
Innovation Solution
A method and apparatus for determining a refined receive beam direction based on decoding broadcast information via a plurality of beams, where log likelihood ratios (LLRs) are calculated for coded bits of the physical broadcast channel (PBCH) received from multiple beams, and successful decoding is used to refine the beam direction, potentially combining LLRs from adjacent beams for improved decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple refined receive beam directions are scanned during initial cell search, then beam direction accuracy is improved, but latency and power consumption increase
Solution Approach 1:
The patent performs preliminary beam sweeping to identify candidate beams before refinement. By pre-identifying beams that contain the target cell's broadcast information, the system avoids scanning all possible beam directions during refinement, thus reducing latency while maintaining accuracy in determining the refined receive beam direction.
Solution Approach 2:
The beam refinement process is segmented into identifying a subset of candidate beams from which to search for the refined beam direction. This segmentation reduces the search space from all possible beam directions to only those candidate beams that are likely to contain the target cell, thereby reducing the time and power required for refinement while maintaining measurement precision.
2Measurement precision
If multiple refined receive beam directions are scanned during initial cell search, then beam direction accuracy is improved, but power consumption increases
Solution Approach 1:
The patent performs preliminary beam sweeping to identify candidate beams before refinement. By pre-identifying beams that contain the target cell's broadcast information, the system avoids scanning all possible beam directions during refinement, thus reducing power consumption while maintaining accuracy in determining the refined receive beam direction.
Solution Approach 2:
The beam refinement process is segmented into identifying a subset of candidate beams from which to search for the refined beam direction. This segmentation reduces the search space from all possible beam directions to only those candidate beams that are likely to contain the target cell, thereby reducing the power required for refinement while maintaining measurement precision.
3Reliability
If beam refinement is performed during initial cell search, then connection establishment reliability is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary beam sweeping to identify candidate beams before refinement. By pre-identifying beams that contain the target cell's broadcast information, the system reduces the number of beams requiring detailed processing during refinement, thus reducing processing complexity while maintaining connection establishment reliability.
Solution Approach 2:
The beam refinement process is segmented into identifying a subset of candidate beams from which to search for the refined beam direction. This segmentation reduces the processing complexity by limiting the refinement operations to a smaller subset of candidate beams rather than processing all possible beam directions, while still ensuring reliable connection establishment.
Data Source
AI summary
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE configured to receive a plurality of beams through a plurality of different receive beam directions, each of the beams including broadcast information on a PBCH. The apparatus may be further configured to determine, for each of a subset of the received beams, a log likelihood ratio (LLR) for coded bits of the broadcast information. The apparatus may be further configured to decode the broadcast information associated with each of the subset of the received beams, and determine a refined receive beam direction based on the determined LLRs and based on whether the broadcast information associated with each of the subset of the received beams fails to decode or is successfully decoded.