Terminal QCL Parameter Derivation via MAC CE
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Solution Overview
Problem
In future radio communication systems, determining Quasi-Co-Location (QCL) parameters for user terminals (UEs) is challenging due to differences between downlink and uplink QCL parameters, leading to potential system performance deterioration.
Innovation Solution
A terminal is equipped with a receiving section to obtain information related to uplink signals and a control section that uses Medium Access Control (MAC) control elements to determine specific spatial relations for transmitting uplink signals, instead of relying on the spatial relations indicated for uplink signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different QCL parameters are used for downlink and uplink signals, then signal transmission can be optimized for each direction, but system performance deteriorates due to complicated UE operations
Solution Approach 1:
The patent merges the determination of QCL parameters for downlink and uplink signals by establishing that the uplink QCL parameter is derived from the downlink QCL parameter through a predefined relationship. This combining approach allows the UE to use the same reference signal for both downlink reception and uplink transmission, thereby optimizing signal transmission while simplifying UE operations by avoiding the need to independently determine separate QCL parameters for each direction.
Solution Approach 2:
The patent applies universality by making a single downlink QCL parameter serve multiple functions: it is used for both downlink signal reception and uplink signal transmission. This multi-functional use of the QCL parameter eliminates the need for separate parameter sets, thereby maintaining transmission optimization while reducing UE operational complexity.
2Adaptability or versatility
If different QCL parameters are used for downlink and uplink signals, then directional transmission can be optimized, but system throughput is reduced
Solution Approach 1:
The patent combines the QCL parameter determination process for both downlink and uplink into a unified mechanism where the uplink QCL parameter is directly derived from the downlink QCL parameter. This merging ensures that the reference signal used for downlink reception is also used for uplink transmission, maintaining directional transmission optimization while improving system throughput by reducing the complexity and potential errors associated with independent parameter determination.
Solution Approach 2:
The patent applies homogeneity by ensuring that the same QCL parameter characteristics are used for both downlink and uplink transmissions. By making the uplink QCL parameter homogeneous with the downlink QCL parameter (derived through predefined relationships), the system maintains consistent transmission optimization across directions while improving throughput through simplified UE operations and reduced parameter management overhead.
3Adaptability or versatility
If separate spatial relations are indicated for uplink signals, then uplink transmission can be independently optimized, but QCL parameter determination becomes complicated
Solution Approach 1:
The patent merges the spatial relation indication for uplink transmission with the downlink QCL parameter by establishing that the uplink spatial relation is derived from the downlink QCL parameter through predefined relationships. This combining approach allows independent uplink transmission optimization while reducing QCL parameter determination complexity, as the UE does not need to independently determine separate spatial relations but can derive them from the downlink parameters.
Solution Approach 2:
The patent applies preliminary action by having the downlink QCL parameter determined first, which then serves as the basis for deriving the uplink spatial relation. This preliminary determination of the downlink parameter simplifies the overall process, as the uplink spatial relation is automatically derived from it through predefined relationships, thereby reducing the complexity of QCL parameter determination while maintaining uplink transmission optimization.
Data Source
AI summary
A terminal according to an aspect of the present disclosure includes: a receiving section that receives information relating to an uplink signal; and a control section that uses, when medium access control (MAC) control element (CE) is indicated and the information satisfies an applicable condition, a specific spatial relation based on the MAC CE for transmitting the uplink signal instead of a spatial relation indicated for the uplink signal. According to an aspect of the present disclosure, QCL parameters can be appropriately determined.