Multi-TRP Random Access for Uplink Timing Advance Synchronization
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Solution Overview
Problem
The current NR system lacks an explicit solution for performing uplink synchronization with multiple transmission reception points (TRPs) due to varying distances between the terminal device and different TRPs, resulting in significant synchronization errors.
Innovation Solution
The terminal device determines and transmits a physical random access channel (PRACH) to each target TRP based on specific random access parameters to obtain timing advance (TA) information, allowing for uplink synchronization with each TRP, even when out-of-sync.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal device transmits PRACH to multiple TRPs simultaneously, then the uplink synchronization accuracy for each TRP is improved, but the device complexity and signaling overhead increase
Solution Approach 1:
The patent segments the random access process by introducing separate random access procedures for each TRP. The terminal device determines TRP-specific random access parameters and transmits separate PRACHs to different TRPs, allowing independent synchronization measurement and adjustment for each TRP, thereby resolving the synchronization accuracy issue while managing complexity through structured segmentation
Solution Approach 2:
The patent adds a TRP dimension to the random access process by introducing TRP identifiers and TRP-specific parameters. This dimensional expansion allows the system to handle multiple TRPs independently, transforming a single synchronization problem into multiple independent synchronization problems that can be solved separately for each TRP
2Measurement precision
If the terminal device uses TRP-specific random access parameters, then the synchronization error is reduced, but the signaling overhead and protocol complexity increase
Solution Approach 1:
The patent applies preliminary action by having the network device pre-configure and indicate TRP-specific random access parameters to the terminal device before the random access procedure. This advance provision of parameters reduces the need for extensive signaling during the actual random access process, as the terminal device can directly use the pre-indicated parameters for PRACH transmission to each TRP
Solution Approach 2:
The patent changes parameters by introducing TRP-specific random access parameters that differ from the conventional single TRP parameters. These parameters include TRP-specific preamble sequences, time resources, and frequency resources, allowing the system to adapt the random access procedure to multiple TRPs with different characteristics while managing signaling overhead through efficient parameter indication
Data Source
AI summary
A method for random access, a terminal device, and a network device are provided. The method includes the following. A terminal device determines a random access parameter for at least one target transmission reception point (TRP), where each of the at least one target TRP is a TRP among multiple TRPs, where an uplink between the TRP and the terminal device is in an out-of-sync state, and at least part of random access parameters for different TRPs are different. The terminal device transmits a physical random access channel (PRACH) to the at least one target TRP based on the random access parameter for the at least one target TRP, where the PRACH is used to obtain timing advance (TA) information for the at least one target TRP.