Multi-TRP Random Access Switching for QCL and PCI Changes
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Solution Overview
Problem
In the context of 5G New Radio (NR) with Multi-TRP scenarios, the application of 2-step random access is restricted due to the requirement that the UE not monitor a Common Search Space (CSS) of type 0/0A/1 with an active TCI state using a Physical Cell Identity (PCI) other than that of the serving cell, leading to limitations in access rate improvement.
Innovation Solution
A method and device for wireless communications that involve receiving a target information block to determine time-frequency resources and performing a random access procedure, where the resources are associated with specific identities, including Physical Cell Identifiers (PCIs), to facilitate 2-step random access even when the QCL relation changes to a PCI other than the serving cell's PCI, ensuring stability and reducing resource waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE monitors CSS with TCI state using PCI other than serving cell's PCI, then the access rate can be improved, but the system stability deteriorates due to protocol restrictions
Solution Approach 1:
The patent introduces dynamic selection of random access procedures based on QCL relation changes. When QCL relation changes to a PCI other than the serving cell's PCI, the system dynamically switches from 2-step RA to 4-step RA, and vice versa. This dynamic adaptation allows the system to maintain stability while improving access rate under different conditions.
Solution Approach 2:
The patent changes the parameter of random access procedure type (2-step vs 4-step) based on QCL relation parameters. By monitoring QCL relation changes and adjusting the random access procedure type accordingly, the system optimizes access rate while maintaining stability through parameter-based adaptation.
2Device complexity
If 2-step random access is restricted under M-TRP scenario, then the system complexity is reduced, but the access rate deteriorates
Solution Approach 1:
The patent implements dynamic selection between 2-step and 4-step random access procedures based on QCL relation changes. When QCL relation remains associated with the serving cell's PCI, the system uses 2-step RA to improve access rate. When QCL relation changes to another PCI, it switches to 4-step RA to maintain system stability. This dynamic approach optimizes the balance between complexity and access rate.
3Productivity
If the UE chooses 2-step random access based on its own condition, then the access rate is improved, but the resource waste increases when QCL relation changes
Solution Approach 1:
The patent introduces feedback mechanism through QCL relation monitoring. The UE continuously monitors QCL relation changes and provides feedback by switching between 2-step and 4-step random access procedures. This feedback-based adaptation prevents resource waste by selecting the appropriate random access type based on current QCL relation state, thereby improving both access rate and resource efficiency.
Data Source
AI summary
The present application provides a method and a device in a node for wireless communications. A node firstly receives a target information block, the target information block being generated in a protocol layer below an RRC layer, the target information block being used to determine a first time-frequency resource; and then performs a first random access procedure, the action of performing the first random access procedure comprising transmitting a first message; the first time-frequency resource is associated with one of a first identity and a second identity; the first message is used for random access; whether the first time-frequency resource is associated with the first identity is used to determine whether the first message is an MsgA or an Msg1. This application improves the criterion for determining 2-step random access in the case of Multi-TRP, thereby enhancing the efficiency of random access and optimizing the system performance.