Aperiodic SRS Triggering via DCI Without PUSCH Scheduling
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Solution Overview
Problem
Current cellular communication systems lack flexibility in triggering aperiodic Sounding Reference Signals (SRS) transmissions, which hinders efficient uplink channel assessment by base stations.
Innovation Solution
A cellular base station configures downlink control information (DCI) to trigger aperiodic SRS transmissions without uplink shared channel data, specifying slot offsets and beam information, and can target multiple UEs efficiently with reduced transmission overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DCI is configured to trigger aperiodic SRS transmissions without uplink shared channel data, then flexibility of SRS triggering is improved, but DCI message complexity increases
Solution Approach 1:
The patent extracts the SRS triggering function from the conventional DCI structure that requires uplink shared channel data. By setting specific field values (UL-SCH indicator to 0, CSI request to all 0s, SRS request to nonzero), the patent separates SRS triggering from data transmission, allowing independent SRS triggering without requiring uplink data payload.
Solution Approach 2:
The patent utilizes parameter changes within the existing DCI format fields to achieve flexible SRS triggering. By dynamically setting different values for UL-SCH indicator, CSI request field, and SRS request field, the system can trigger aperiodic SRS transmissions with varying configurations (different time offsets, frequency offsets, resource indicators) without changing the fundamental DCI structure.
2Loss of energy
If DCI targets multiple UEs with SRS triggering, then transmission overhead is reduced, but UE identification complexity increases
Solution Approach 1:
The patent merges multiple SRS triggering operations into a single DCI message by utilizing the SRS request field to indicate multiple UEs. This allows the base station to trigger aperiodic SRS transmissions from multiple UEs simultaneously, reducing the number of separate DCI messages needed and thereby reducing overall transmission overhead.
Solution Approach 2:
The patent implements a feedback mechanism where UEs monitor DCI messages for their specific SRS triggering conditions. Each UE checks the DCI fields (particularly the SRS request field and associated resource indicators) to determine if the message is intended for it, allowing efficient multi-UE targeting without requiring complex explicit identification in the DCI payload.
Data Source
AI summary
A cellular base station (BS) which transmits more flexible downlink control information (DCI) to the UE, and a UE capable of receiving and processing a received DCI message. The DCI message may have a DCI format of 0_1 or 0_2 and further may comprise an UL-SCH set to 0, a CSI request field of all 0s and an SRS request field having a nonzero value. The DCI message may indicate to the UE that the UE should: 1) transmit an aperiodic SRS corresponding to SRS request; and 2) that the UE should not transmit on the PUSCH. The DCI may include existing fields that specify either a slot offset or beam information useable when transmitting the aperiodic SRS. The base station may also generate a DCI message with an SRS trigger that is targeted to a plurality of UEs in a group, or a plurality of groups of UEs, for greater efficiency.