Multi-Modal Beam Alignment for Millimeter-Wave Initial Access
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Solution Overview
Problem
Conventional beam alignment methods in millimeter-wave communication systems are inefficient, leading to increased search time and radio resource consumption during the initial access stage due to the limited number of synchronization signals used, which results in higher propagation loss and longer delays.
Innovation Solution
The method employs multi-modal beam patterns with non-overlapping main lobes for synchronization signal transmission, allowing user equipment to determine the strongest signal and transmit an initial access message, while the base station uses single-modal beam patterns to determine the optimal beam direction, reducing the number of required synchronization signals and improving angular resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of synchronization signals is increased to improve angular resolution, then beam alignment precision is improved, but search time and radio resource consumption increase
Solution Approach 1:
The patent divides the beam alignment process into two stages: a coarse search stage using multi-modal beam patterns with multiple main lobes to quickly identify the general beam direction, and a fine search stage using single-modal beam patterns to determine the precise optimal beam direction. This segmentation allows the system to achieve high angular resolution without requiring all possible beam patterns to be transmitted simultaneously, thereby reducing search time while maintaining precision.
Solution Approach 2:
The patent employs multi-modal beam patterns with multiple main lobes in the preliminary stage to pre-identify the general beam direction before performing the final precise measurement. By using beam patterns that cover multiple angular regions simultaneously, the system performs preliminary action to narrow down the search space, reducing the time required for subsequent precise beam alignment.
2Measurement precision
If the number of synchronization signals is increased to improve beam alignment precision, then angular resolution is improved, but radio resource consumption increases
Solution Approach 1:
The patent segments the beam alignment process into coarse and fine search stages, using different beam pattern types for each stage. The coarse stage uses multi-modal beam patterns to quickly establish the general beam direction with fewer signals, while the fine stage uses single-modal beam patterns for precise alignment. This segmentation reduces the total number of synchronization signals needed compared to using only single-modal patterns throughout, thereby reducing radio resource consumption while maintaining angular resolution.
Solution Approach 2:
The patent applies partial action by using multi-modal beam patterns that cover multiple angular regions simultaneously, rather than transmitting separate signals for each individual beam direction. This allows the system to gather information about multiple beam directions from a single synchronization signal, reducing the total number of signals required while still achieving comprehensive angular coverage and resolution.
3Measurement precision
If conventional sequential search is used for beam alignment, then beam direction can be determined, but search delay increases significantly
Solution Approach 1:
The patent performs preliminary action by using multi-modal beam patterns with multiple main lobes to quickly identify the general beam direction before executing the final precise measurement. This preliminary coarse search dramatically reduces the search space for the subsequent fine search stage, thereby significantly reducing the overall search delay while maintaining accurate beam direction determination.
Solution Approach 2:
The patent segments the beam alignment process into two sequential but efficiently executed stages: a coarse search stage using multi-modal beam patterns to rapidly narrow down the beam direction, and a fine search stage using single-modal beam patterns for precise determination. This segmentation allows the system to avoid the excessive delay of sequential search through all possible beam patterns by stopping the coarse search early once the general direction is identified.
Data Source
AI summary
A beam alignment method for an antenna array is provided. In the method, a base station uses multi-modal beam patterns for transmitting several synchronization signals. User equipment scans the synchronization signals, determines a synchronization signal with the strongest received power and a receive beam direction corresponding thereto, and transmits an initial access message including index information indicating the strongest synchronization signal. The base station receives the initial access message on the random access channel by using the single-modal beam patterns, determines a single-modal beam pattern with the strongest access power for the initial access message, and compares the determined single-modal beam pattern with the strongest access power with a main lobe of the multi-modal beam pattern corresponding to the index information indicating the synchronization signal with the strongest received power in the initial access message, to determine an optimal beam direction for the transmission to the user equipment.