Random Access Preamble Beam Indexing for Mobile Communication Systems
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Solution Overview
Problem
In next-generation mobile communication systems, the lack of a defined mechanism for informing beam indices leads to complications during random access procedures, particularly when beam correspondence at the base station is unknown, resulting in terminals receiving multiple random access responses (RARs).
Innovation Solution
A method for random access in a multi-beam-based mobile communication system involves receiving synchronization signal blocks to obtain beam index information, transmitting a preamble message occupying multiple preamble resources corresponding to the beam index, and selecting an optimal beam for downlink and uplink transmission, allowing the base station to recognize the optimal beam and respond with a random access response (RAR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming technology is used to increase beam forming gain in specific direction, then signal transmission quality is improved, but the complexity of random access procedure increases due to multiple beams
Solution Approach 1:
The patent introduces a beam index as an intermediary element that mediates between the terminal and base station during random access. The terminal determines the beam index based on received synchronization signals and includes it in the preamble message, allowing the base station to identify the optimal beam without complex multi-beam coordination procedures.
Solution Approach 2:
The patent performs preliminary beam determination before the random access procedure by having the terminal measure synchronization signal reception quality across multiple beams and identify the optimal beam index in advance. This preliminary action simplifies the subsequent random access by eliminating the need for complex beam selection during the access procedure itself.
2Measurement precision
If the base station transmits reference signals for each beam, then the terminal can measure channel state of each beam, but the random access procedure becomes complicated when beam correspondence is unknown
Solution Approach 1:
The patent extracts the beam index information from the complex multi-beam environment and transmits it separately through the preamble message. By taking out the beam identification element and handling it independently, the system avoids the complexity of coordinating multiple beams during random access while maintaining precise channel state measurement capability.
3Loss of information
If a preamble message occupies multiple preamble resources, then beam index information can be communicated, but resource allocation complexity increases
Solution Approach 1:
The patent merges the beam index information transmission with the existing preamble message structure. Instead of creating separate resources for beam index communication, the solution combines both functions into a single preamble transmission, thereby reducing resource allocation complexity while ensuring complete information transfer.
Data Source
AI summary
A method and an apparatus for random access in a mobile communication system are provided. A terminal receives a synchronization signal block, obtains beam index information from the received synchronization signal block, and transmits a preamble message occupying a plurality of preamble resources including a preamble resource corresponding to the beam index information to a base station. A random access resource includes a plurality of preamble resources, and the synchronization signal block is specified for one beam and corresponds to one preamble resource of the random access resource.