Random Access Switching for mmWave Beam Tracking Failures
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Solution Overview
Problem
The two-step random access method in 3GPP experiences reduced success rates due to inadequate downlink beam tracking, particularly in millimeter wave frequency bands, leading to poor demodulation performance of the message A, which affects access performance.
Innovation Solution
A method that switches from a two-step random access to a four-step random access through a back-off mechanism when certain conditions are met, such as poor signal quality of synchronization signal and PBCH blocks, ensuring better demodulation performance by using the four-step method when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If two-step random access is used, then access speed is improved, but demodulation performance deteriorates due to inadequate downlink beam tracking
Solution Approach 1:
The patent implements dynamic switching between two-step and four-step random access procedures based on downlink beam tracking conditions. When beam tracking performance is adequate, the system uses two-step random access for fast access; when beam tracking performance degrades below a threshold, the system switches to four-step random access to maintain reliable demodulation. This dynamic adaptation resolves the contradiction by allowing the system to optimize for speed when conditions permit and for reliability when conditions deteriorate.
2Manufacturing precision
If four-step random access is used, then demodulation performance is improved, but access speed deteriorates compared to two-step method
Solution Approach 1:
The system dynamically selects between four-step and two-step random access based on real-time assessment of downlink beam tracking conditions. The four-step procedure is employed as a fallback mechanism that activates only when beam tracking performance falls below the required threshold, ensuring reliable demodulation at the cost of increased access time. This dynamic selection resolves the speed-performance tradeoff by using the more robust but slower four-step method only when necessary.
3Measurement precision
If SSB threshold is set high, then downlink beam selection accuracy is improved, but random access success rate deteriorates when all SSBs are below threshold
Solution Approach 1:
The patent implements a dynamic random access procedure selection mechanism that adapts to downlink beam tracking conditions. When beam tracking performance is adequate, the system uses two-step random access with high SSB thresholds for accurate beam selection. When beam tracking deteriorates and all SSBs fall below the threshold, the system switches to four-step random access, which maintains reliability by allowing random selection of preamble resources without strict beam alignment requirements. This dynamic adaptation resolves the contradiction between selection accuracy and access success rate.
4Quantity of substance
If two-step random access is used, then signaling overhead is reduced, but access reliability deteriorates in millimeter wave frequency bands
Solution Approach 1:
The system dynamically selects between two-step and four-step random access procedures based on downlink beam tracking conditions, which are particularly critical in millimeter wave frequency bands. The two-step procedure is used when beam tracking conditions are good, providing low signaling overhead. When beam tracking deteriorates in mmWave conditions, the system switches to the more robust four-step procedure, which uses separate random access preamble transmission and uplink data transmission, thereby maintaining access reliability despite increased signaling overhead. This dynamic selection resolves the contradiction between overhead reduction and reliability maintenance in challenging mmWave environments.
Data Source
AI summary
A random access method, a device, and a medium. The random access method includes: receiving configuration information, the configuration information being used to instruct to enable a back-off function of a random access process; and switching from a two-step random access to a four-step random access by a back-off in response to a synchronization signal and PBCH block (SSB) based random access meeting a target condition.