Preamble Beam Selection for Multi-TRP Random Access
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Solution Overview
Problem
Conventional contention-free random access methods in multi-TRP scenarios fail to ensure that network devices other than the base station can receive preambles sent by a terminal.
Innovation Solution
A preamble sending method where a terminal determines a path loss reference signal and/or beam for sending a preamble based on information in a PDCCH order, which may not be quasi-co-located with the reference signal used to receive the PDCCH order, ensuring accurate reception by multiple TRPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the terminal uses the reference signal used to receive the PDCCH order as the path loss reference signal for preamble transmission, then the terminal can simplify the signal selection process, but other TRPs cannot receive the preamble in multi-TRP scenarios
Solution Approach 1:
The patent segments the path loss reference signal selection by introducing a new parameter (pathLossReferenceSignal) in the PDCCH order that explicitly indicates which reference signal should be used. This separates the reference signal used for PDCCH reception from the reference signal used for path loss calculation, allowing different TRPs to be served by different reference signals while maintaining clear operational procedures for the terminal.
Solution Approach 2:
The patent introduces an intermediary mechanism through the pathLossReferenceSignal indicator in the PDCCH order, which acts as a mediator between the network's multi-TRP configuration and the terminal's single reference signal selection. This intermediary allows the network to specify which TRP's reference signal the terminal should use for path loss calculation, enabling other TRPs to receive the preamble effectively.
2Stability of the object's composition
If the terminal uses the receive beam of the SSB/CSI-RS QCLed with the PDCCH order DM-RS as the beam for sending the preamble, then the terminal can maintain beam consistency, but other TRPs cannot receive the preamble
Solution Approach 1:
The patent segments the beam selection process by allowing the network to indicate a specific TCI state in the PDCCH order that corresponds to the desired receive beam. This separates the beam used for PDCCH reception from the beam that should be used for preamble transmission, enabling the terminal to maintain beam consistency with the indicated TCI state while allowing other TRPs to receive the preamble effectively.
Solution Approach 2:
The TCI state indicator in the PDCCH order serves as an intermediary that bridges the network's multi-TRP beam configuration and the terminal's single beam selection. This intermediary allows the network to specify which TCI state (and thus which receive beam) the terminal should use for preamble transmission, enabling multi-TRP reception while maintaining beam consistency for the terminal.
Data Source
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AI summary
This disclosure provides a preamble sending method and apparatus, a terminal and a network device. The method includes: receiving, by a terminal, a physical downlink control channel (PDCCH) order sent by a first network device; determining, by the terminal, according to information included in the PDCCH order, a path loss reference signal and/or a beam for sending a preamble; and sending, by the terminal, the preamble according to the path loss reference signal and/or beam.