RACH Window Timing Coordination with Beam Discovery
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Solution Overview
Problem
In millimeter wave (mmW) shared spectrum wireless communication systems, Random Access Channel (RACH) procedures often fail due to misalignment of directional beams between base stations and user equipment (UE), leading to inefficiencies in resource allocation and communication success.
Innovation Solution
The method involves coordinating the RACH procedure with a beam discovery procedure by aligning the timing and configuration of the RACH window with the beam discovery window, allowing the UE to use information from the beam discovery process to improve the likelihood of successful RACH transmissions. This is achieved by triggering the RACH procedure based on the receipt of directional beam discovery signals and using a static or dynamic configuration relative to the beam discovery window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RACH procedure is performed without beam discovery coordination, then procedure simplicity is maintained, but RACH success rate deteriorates due to beam misalignment
Solution Approach 1:
The patent applies preliminary action by performing beam discovery before the RACH procedure. The base station transmits beam discovery signals (BDS) in advance, allowing the UE to identify the optimal beam direction. This preliminary beam alignment ensures that when the RACH procedure subsequently occurs, both transmitter and receiver are already configured with the correct beam directions, thereby improving RACH success rate without requiring complex real-time beam switching during the RACH itself.
Solution Approach 2:
The patent uses beam discovery signals as an intermediary element between the beam alignment requirement and the RACH procedure. These BDS serve as a mediator that carries beam direction information from the base station to the UE, enabling the UE to determine the appropriate receive beam direction before attempting RACH transmission. This intermediary mechanism decouples the complexity of beam management from the RACH procedure while ensuring reliable beam alignment.
2Reliability
If RACH window timing is independently configured, then configuration flexibility is maintained, but beam alignment reliability deteriorates
Solution Approach 1:
The patent merges the RACH window timing configuration with the beam discovery window configuration. Specifically, the RACH window is positioned to overlap with or immediately follow the beam discovery window, ensuring that the UE performs beam discovery and RACH procedure using the same beam alignment information. This merging ensures that beam alignment reliability is maintained while still allowing the system to adapt to different scenarios through configurable timing offsets and window durations.
Solution Approach 2:
The patent introduces dynamic timing configuration where the RACH window timing is adjusted based on the beam discovery window timing. The system can dynamically configure the offset between these windows according to specific deployment scenarios, traffic conditions, and beam characteristics. This dynamic approach maintains beam alignment reliability by ensuring synchronization while preserving adaptability through configurable parameters that can be adjusted based on network conditions.
3Productivity
If beam discovery and RACH are performed separately, then procedure modularity is maintained, but resource efficiency deteriorates due to potential retransmissions
Solution Approach 1:
The patent applies preliminary action by completing beam discovery before initiating the RACH procedure. The base station transmits beam discovery signals and the UE identifies the optimal beam direction in advance, storing this information for use in the subsequent RACH procedure. This preliminary beam alignment eliminates the need for repeated beam searching during RACH retransmissions, thereby improving resource efficiency by reducing the probability of failed attempts while maintaining procedural modularity through distinct but coordinated phases.
Data Source
AI summary
Techniques are described herein for coordinating a random access channel (RACH) procedure with a beam discovery procedure. A timing and configuration of a RACH window may be coordinated with a beam discovery window. By coordinating the two windows, a user equipment (UE) may be configured to use information learned from the beam discovery procedure during the RACH procedure, thereby increasing the likelihood that the RACH procedure is successful. In some cases, the RACH procedure is triggered by the transmission of directional beam reference signals during the beam discovery window. In such cases, the UE determines the timing of the RACH window based at least in part on the receipt of the directional beam reference signals. In some cases, the RACH window is configured using a static configuration relative to the beam discovery window.