Cross-Carrier TCI Mapping for Transmit-Receive Beam Alignment
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Solution Overview
Problem
In scenarios involving cross-carrier scheduling, terminal devices struggle to determine the correct TCI state for receive beams, leading to inconsistent beamforming gains and poor downlink signal transmission quality due to mismatched TCI states between network and terminal devices.
Innovation Solution
A method for determining a shared mapping relationship between TCI states and beams using indication information, allowing network and terminal devices to pair transmit and receive beams through beam training, ensuring consistent beamforming gains by aligning TCI states across carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling is implemented to increase transmission bandwidth, then carrier aggregation capability is improved, but terminal device ability to determine correct TCI state deteriorates
Solution Approach 1:
The patent introduces an intermediary mapping relationship between TCI values and TCI states. When the terminal receives TCI indication information, it first maps the TCI value to the appropriate TCI state using the pre-configured mapping relationship specific to the indicated BWP. This intermediary mapping mechanism resolves the ambiguity caused by cross-carrier scheduling, allowing the terminal to correctly determine the TCI state even when PDCCH and PDSCH are on different carriers.
2Adaptability or versatility
If TCI states are received from multiple CCs during cross-carrier scheduling, then carrier flexibility is improved, but beam determination accuracy deteriorates
Solution Approach 1:
The patent applies local quality by configuring different mapping relationships for different BWPs on different CCs. Each BWP has its own specific mapping relationship between TCI values and TCI states. When the network indicates a specific BWP, the terminal uses only the mapping relationship local to that BWP, not mapping relationships from other CCs. This ensures that the TCI state determination is precise and specific to the indicated BWP, resolving the confusion caused by receiving TCI states from multiple CCs.
3Reliability
If beam training is performed to obtain transmit-receive beam pairing, then beamforming gain is improved, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by performing beam training in advance to establish the mapping relationship between TCI values, TCI states, and beam identifiers. This mapping relationship is configured and stored beforehand. During actual data transmission, the terminal only needs to look up the pre-established mapping relationship based on the received TCI indication, rather than performing complex beam training and pairing operations in real-time. This preliminary preparation maintains beamforming gain while significantly reducing real-time system complexity.
Data Source
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AI summary
This application provides a signal receiving and sending method and a communications apparatus, to help improve signal transmission quality. The method includes: A terminal device receives, on a first CC, first indication information from a network device, where the first indication information is used to indicate a BWP for transmitting a downlink signal and a second CC to which the BWP belongs; the terminal device and the network device separately determine a first mapping relationship in a plurality of pre-obtained mapping relationships based on the second CC and the BWP, where the first mapping relationship is used to indicate a correspondence between at least one TCI state and at least one TCI, and the terminal device and the network device may determine a TCI state based on the first mapping relationship and a TCI; the network device may determine, based on the TCI state, a transmit beam for sending the downlink signal, and send the downlink signal by using the transmit beam; and the terminal device may determine, based on the TCI state, a receive beam for receiving the downlink signal, and receive the downlink signal by using the receive beam.