Aperiodic SRS Slot Offset Collision Avoidance
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Solution Overview
Problem
The dynamic change in TDD slot formats can lead to collisions between aperiodic SRS resource sets in NR wireless communication systems, as existing configurations do not provide clear rules for handling such collisions, especially with the introduction of enhanced DCI triggering flexibility in NR Rel-17.
Innovation Solution
A framework is provided for updating the aperiodic SRS slot offset parameter 't' using MAC CE signaling, allowing for both explicit and implicit methods to dynamically adjust the slot offset, thereby avoiding collisions by associating t-values with SRS trigger states or DCI codepoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aperiodic SRS resource sets are configured with fixed slot offsets, then SRS transmission timing is determined, but collisions occur when TDD slot formats change dynamically
Solution Approach 1:
The patent applies dynamics by enabling the slot offset parameter 't' to be updated dynamically through MAC CE signaling. Instead of using fixed RRC-configured slot offsets, the system allows the gNB to adjust the slot offset value dynamically via MAC CE commands, enabling the SRS transmission timing to adapt to changing TDD slot formats while maintaining reliable transmission by avoiding collisions.
Solution Approach 2:
The patent changes the parameter 't' (slot offset) from a static RRC configuration to a dynamic parameter that can be updated through MAC CE signaling. This parameter change allows the system to adjust the SRS transmission timing adaptively in response to dynamic TDD slot format changes, resolving the contradiction between reliability and adaptability.
2Stability of the object's composition
If RRC configuration is used for SRS slot offset, then configuration is stable, but updates require RRC reconfiguration which increases latency
Solution Approach 1:
The patent introduces MAC CE signaling as an intermediary mechanism between the stable RRC configuration and the need for dynamic updates. The RRC configuration provides the stable framework and initial parameters, while MAC CE commands serve as the intermediary that enables fast, low-latency updates of the slot offset parameter without requiring full RRC reconfiguration, thus resolving the contradiction between stability and update speed.
3Adaptability or versatility
If multiple SRS resource sets are triggered by the same DCI, then triggering flexibility is improved, but collision handling becomes complex without clear rules
Solution Approach 1:
The patent applies feedback by implementing a mechanism where the gNB provides MAC CE commands that feedback the updated slot offset values to the UE. This feedback mechanism allows multiple SRS resource sets triggered by the same DCI to have their timing dynamically adjusted, providing clear rules for collision handling while maintaining the triggering flexibility, thus resolving the contradiction between adaptability and complexity.
Data Source
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AI summary
There is provided a method, in a wireless device, for transmitting a reference signal. The method comprises: receiving a configuration via Radio Resource Control (RRC) from a network node, the configuration comprising a list of slot offset values configured for a Sounding Reference Signal (SRS) resource set; receiving Downlink Control Information (DCI) triggering the SRS resource set, wherein the DCI contains a slot offset bitfield for indicating one of the slot offset values in the list of slot offset values and wherein each entry of the list of slot offset values corresponds to a codepoint of the slot offset bitfield; and transmitting a reference signal using SRS resources configured in the triggered SRS resource set based on the indicated slot offset value.