Wireless Random Access Beam Association with Merged RAR Messages
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Solution Overview
Problem
In wireless communication networks, particularly above 6 GHz, the efficient transmission of synchronization signals and random access responses is hindered by unclear associations between DL Tx beams and UL Rx beams, leading to increased signaling overhead and inefficient resource utilization due to the need for repeated transmissions with multiple Tx beams.
Innovation Solution
A method and apparatus for flexible SS block transmission patterns that reduce signaling overhead by allowing SS blocks to be transmitted in consecutive slots, with dynamic TDD operation support, and efficient RAR message delivery using RA-RNTI-based PDCCH and PDSCH transmissions with beamforming techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple SS blocks are transmitted with different Tx beams to cover different spatial directions, then coverage is improved, but signaling overhead increases due to repeated RAR message transmissions
Solution Approach 1:
The patent combines multiple RAR messages into a single transmitted RAR message by including multiple MAC RARs for different UEs and/or different SS blocks within one message structure. This merging approach allows the NE to respond to multiple random access preambles detected on different SS blocks using a single RAR transmission, thereby reducing the number of repeated transmissions and lowering signaling overhead while maintaining support for multi-beam operation
Solution Approach 2:
The RAR message structure is designed to be universal by incorporating multiple MAC RARs that can serve different purposes - responding to preambles from different SS blocks, different UEs, or both. This multi-functional RAR message can handle various random access scenarios (contention-based and contention-free) across multiple beams simultaneously, reducing the need for separate dedicated RAR transmissions for each beam
2Productivity
If RACH resources are associated with multiple SS blocks to reduce overhead, then resource efficiency is improved, but beam association clarity deteriorates
Solution Approach 1:
The patent segments the RAR message into multiple MAC RARs, where each MAC RAR can be associated with a specific SS block or UE. This segmentation allows the NE to maintain clear beam association information within each MAC RAR while using a single unified RAR message structure. The segmentation enables precise tracking of which RAR responds to which preamble and SS block combination, preserving beam association clarity despite serving multiple beams
Solution Approach 2:
The patent introduces an intermediary mapping mechanism between RACH resources and SS blocks that is configured by the NE. This mapping relationship serves as an intermediary that connects the reduced RACH resources to multiple SS blocks while maintaining the ability to identify which SS block each preamble originated from. The mapping acts as a mediator that preserves beam association information even when multiple SS blocks share common RACH resources
3Loss of time
If SS blocks are transmitted in consecutive slots with flexible patterns, then latency is reduced, but device complexity increases
Solution Approach 1:
The patent implements dynamic SS block transmission patterns where the NE can flexibly configure SS block positions, periodicities, and associations with RACH resources based on current network conditions and traffic requirements. This dynamic configuration allows optimization of access latency for different scenarios while the NE manages the complexity through centralized control. The dynamics principle enables adaptive adjustment of transmission parameters to balance latency reduction with manageable complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces network and UE power consumption, enhances resource utilization, and improves latency performance by optimizing SS block transmission and RAR message delivery in multi-beam environments.
Implementation Method 1
efficient RAR message delivery using RA-RNTI-based PDCCH and PDSCH transmissions with beamforming techniques
Data Source
AI summary
A radio resource control message comprising an indication of a random access channel preamble, a reference signal resource, or both can be received. A reference signal can be received on the reference signal resource. A random access channel preamble can be selected based at least in part on the reference signal satisfying a threshold. The selected random access channel preamble can be transmitted during a random access procedure.