Default SRS Configuration for Uplink MIMO Before TCI Activation
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing uplink multiple input multiple output (MIMO) transmissions due to the need for medium access control (MAC-CE) to select a subset of uplink TCI states, which can lead to ambiguity and inefficiencies in beam management.
Innovation Solution
Implementing a default sounding reference signal (SRS) resource configuration based on downlink control information (DCI) prior to MAC-CE selection, allowing for unambiguous uplink MIMO communication without requiring immediate MAC-CE down-selection of TCI states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MAC-CE is used to select a subset of uplink TCI states, then beam management flexibility is improved, but transmission latency and complexity increase
Solution Approach 1:
The patent applies preliminary action by configuring the complete uplink TCI state pool in advance through RRC signaling before any MAC-CE selection occurs. This allows the UE to have all necessary beam information pre-available, eliminating waiting time for TCI state configuration and reducing transmission latency while maintaining beam management flexibility through subsequent MAC-CE selection.
2Measurement precision
If MAC-CE selection of TCI states is implemented, then beam management precision is improved, but system complexity increases
Solution Approach 1:
The patent segments the TCI state configuration process into two distinct phases: (1) RRC signaling configures the complete TCI state pool with all beam information, and (2) MAC-CE selects the active subset. This segmentation separates the complex configuration task from the selection task, reducing overall system complexity while maintaining precise beam management through the MAC-CE selection mechanism.
Solution Approach 2:
By pre-configuring the complete TCI state pool through RRC signaling before MAC-CE selection, the patent eliminates the need for the system to handle dynamic TCI state creation and management during transmission. This preliminary action simplifies the system architecture while preserving precise beam management capabilities.
3Productivity
If uplink MIMO transmission is performed before TCI state activation, then communication efficiency is improved, but ambiguity in beam selection occurs
Solution Approach 1:
The patent resolves beam selection ambiguity by preliminarily configuring the complete uplink TCI state pool through RRC signaling before any MAC-CE selection or uplink MIMO transmission occurs. This ensures that when MAC-CE selects a subset of TCI states, the UE has unambiguous beam information immediately available, enabling efficient uplink MIMO transmission without information loss or selection ambiguity.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station may transmit, and a user equipment (UE) may receive, downlink control information (DCI) scheduling an uplink multiple input multiple output (MIMO) communication. The UE may transmit, and the base station may receive, the uplink MIMO communication using a default sounding reference signal (SRS) resource configuration based at least in part on the UE receiving the DCI prior to a medium access control (MAC) control element (MAC-CE) selecting a subset of uplink transmission configuration indication (TCI) states included in an uplink TCI state pool configured for the UE. Numerous other aspects are provided.