SPS Reception Timing for Limited-Capability UE ACK/NACK
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Solution Overview
Problem
In 3GPP Release 16, limited capability UEs face challenges in receiving both a unicast PDSCH symbol and an SPS Release indicator in the same slot, leading to difficulties in sending ACK/NACK feedback due to the inability to process multiple DCIs within a single slot.
Innovation Solution
The solution involves allowing the SPS Release indicator to be transmitted in a second portion of the slot, ensuring sufficient time for the UE to send an ACK/NACK by separating the Release DCI from the SPS symbol, thereby enabling the UE to handle both unicast PDSCH and SPS Release within the same slot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semi-persistent scheduling is used to improve resource allocation efficiency, then resource utilization is improved, but power consumption increases for limited capability devices
Solution Approach 1:
The patent applies partial action by enabling SPS reception only when actually needed rather than continuously. The UE monitors for SPS activation indications and only performs SPS reception operations when triggered, avoiding unnecessary power consumption while maintaining resource allocation efficiency when required.
Solution Approach 2:
The system enables limited capability devices to self-determine when SPS reception is needed by monitoring for activation indications from the network. The device autonomously activates or deactivates SPS reception based on received indications without requiring continuous network control, optimizing power usage while maintaining efficiency.
2Reliability
If continuous monitoring of downlink control channels is performed to ensure reliable reception, then reception reliability is improved, but power consumption increases
Solution Approach 1:
Instead of continuous monitoring, the patent implements periodic monitoring where the UE only monitors downlink control channels for SPS activation indications at specific intervals or when triggered by network indications. This periodic approach maintains reception reliability by checking at appropriate moments while significantly reducing power consumption compared to continuous monitoring.
Solution Approach 2:
The patent extracts the essential monitoring function from continuous operation, keeping only the critical moments when SPS activation indications are expected. By removing unnecessary continuous monitoring periods and retaining only the essential detection moments, the system maintains reliability while reducing power consumption.
3Device complexity
If simplified procedures are used to reduce complexity, then device complexity is reduced, but resource allocation efficiency deteriorates
Solution Approach 1:
The patent makes the SPS mechanism universally applicable to both limited capability devices and regular UEs through a unified procedure. The same downlink control channel monitoring and activation indication mechanisms are used across different device types, reducing the need for device-specific complex procedures while maintaining efficient resource allocation for all devices.
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AI summary
Wireless communication devices, systems, and methods related to downlink control information (DCI) monitoring and semi-persistent scheduling (SPS) reception for limited capability devices are provided. For example, a method of wireless communication performed by a user equipment can include receiving, from the base station, a semi-persistent scheduling (SPS) grant, the SPS grant indicating a periodicity; monitoring, in a slot scheduled for a downlink data communication, for an SPS release and the downlink data communication; and transmitting, to the base station, an acknowledgement (ACK) or negative acknowledgment (NACK) based on the monitoring.