Fast Beam Tracking in High Frequency Wireless Systems
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Solution Overview
Problem
In high-frequency wireless communication environments, the increased number of available beams results in narrower beam widths, making them more prone to failure. This requires the user equipment (UE) to quickly identify beam failures and switch to new beams, which is challenging due to the reduced symbol size caused by higher subcarrier spacing.
Innovation Solution
The UE is configured to receive and configure multiple beams for testing and immediate use. It can receive multiple beams for testing, assume a default beam, and feed back a preferred beam to the base station. To support the increased number of beams, the MAC-CE and DCI are modified to identify additional states, with the option to send two MAC-CEs containing different groups of states and the DCI identifying both the group and the selected state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher frequency is used to increase the number of antennas and beams, then the number of available beams increases, but the beam width becomes narrower and more prone to failure
Solution Approach 1:
The system pre-configures multiple TCI states and corresponding beams before beam failure occurs. The UE is prepared with multiple candidate beams and their associated TCI states, enabling rapid switching without waiting for failure detection and recovery procedures. This preliminary configuration of multiple beams resolves the contradiction by ensuring beam diversity (increasing quantity) while maintaining reliability through pre-prepared backup beams.
Solution Approach 2:
The system modifies MAC-CE and DCI parameters to support identification of increased number of TCI states. By changing the parameter structure (adding bits to identify more states), the system can manage a larger number of beams at high frequency while maintaining reliable beam selection through enhanced state identification mechanisms.
2Speed
If multiple TCI states are configured to support fast beam switching, then beam switching speed improves, but the complexity of MAC-CE and DCI increases
Solution Approach 1:
The system segments the TCI state identification into multiple fields within DCI: a first field identifies a group of TCI states, and a second field identifies the specific TCI state within that group. This segmentation allows efficient beam switching by organizing states in a hierarchical structure, reducing the complexity burden on MAC-CE and DCI while enabling fast beam switching through structured state identification.
Solution Approach 2:
The system adds an additional dimension to TCI state identification by introducing group-level identification alongside state-level identification. Instead of a single flat identifier, the system uses a two-dimensional approach (group index + state index within group), which efficiently manages multiple TCI states while controlling the complexity of MAC-CE and DCI through structured organization.
3Measurement precision
If the UE monitors multiple TCI states for beam failure detection, then beam failure detection accuracy improves, but the processing time and complexity increase
Solution Approach 1:
The UE is pre-configured with multiple TCI states and their corresponding beams before beam failure occurs. This preliminary configuration allows the UE to immediately monitor multiple beams simultaneously without sequential processing, improving detection accuracy while minimizing processing time. The UE can detect beam failure on any monitored beam and switch to a pre-prepared alternative beam rapidly.
Solution Approach 2:
The system enables the UE to autonomously monitor multiple TCI states and automatically select alternative beams upon detecting failure. The UE self-manages the beam monitoring and switching process using the pre-configured TCI states, improving both detection accuracy and response speed by eliminating the need for extensive base station processing and coordination during beam failure events.
Data Source
AI summary
Methods and apparatuses are disclosed for performing fast beam switching in a high-frequency wireless communication environment. Higher frequencies reduce transmission wavelength, which allows for an increased number of antennas and an increased number of beams. Therefore, beams become narrower and are more prone to failure. The UE must be capable of quickly identifying the beam failure and switching to a new beam. Therefore, the UE is capable of receiving multiple beams from the base station and configures both for testing and immediate use. In some cases, the UE can receive multiple beams for testing and assumes a default beam while feeding back to the base station a preferred beam. To support the larger number of available beams, MAC-CE and DCI are modified to identify this increased number of states. Alternatively, two MAC-CEs are sent, each containing a different group of states, and the DCI identifies both the group and the selected state.