PUR and SRS Multiplexing for RedCap UE Energy Efficiency
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Solution Overview
Problem
Current wireless communication technologies, such as 5G NR and LTE, face challenges in improving energy efficiency and scalability, particularly for reduced capability user equipment (RedCap UEs) that require efficient resource allocation and reliable small data transfer in non-connected modes.
Innovation Solution
The technique involves multiplexing preconfigured uplink resources (PUR) and sounding reference signals (SRS) to enable efficient resource allocation, reduce latency, and enhance reliability for RedCap UEs by allowing SRS-assisted tracking and channel sounding, even in inactive states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PUR resources are allocated for RedCap UEs in non-connected modes, then energy efficiency is improved, but resource allocation complexity increases
Solution Approach 1:
PUR resources are pre-configured and allocated to RedCap UEs before actual data transmission is needed. The network entity pre-allocates time-frequency resources and configurations for uplink transmissions, allowing UEs to immediately transmit small data packets without going through complex connection setup procedures, thereby improving energy efficiency while managing allocation complexity through advance planning
Solution Approach 2:
The resource allocation is segmented into specific PUR occasions and SRS resources that are separately configured and managed. By dividing the uplink resources into distinct PUR transmissions and SRS transmissions with separate configurations, the system can efficiently manage each segment independently, reducing overall allocation complexity while maintaining energy efficiency benefits
2Loss of time
If SRS transmissions are multiplexed with PUR occasions, then latency is reduced, but signal interference increases
Solution Approach 1:
SRS and PUR transmissions are multiplexed by utilizing different frequency resources within the same time occasion. The network entity configures SRS and PUR with different frequency offsets, allowing both signals to transmit simultaneously without time-domain collision. This frequency-domain separation reduces latency by enabling parallel transmissions while minimizing signal interference through orthogonal frequency resource allocation
Solution Approach 2:
The system dynamically adjusts the frequency offset configurations for SRS and PUR transmissions based on channel conditions and interference levels. The network entity can reconfigure the frequency resources for SRS and PUR occasions to optimize performance, allowing flexible adaptation that maintains low latency while managing signal interference through dynamic resource reallocation
3Reliability
If SRS-assisted tracking is enabled for RedCap UEs, then reliability of small data transfer is improved, but device complexity increases
Solution Approach 1:
RedCap UEs autonomously perform SRS transmissions according to pre-configured parameters without requiring real-time network control or complex processing. The UE self-manages the timing, frequency, and power of SRS transmissions based on stored configurations, enabling reliable channel sounding and uplink timing offset tracking while keeping device complexity low through simplified autonomous operation
Solution Approach 2:
The SRS transmissions serve multiple functions simultaneously: channel sounding for link adaptation, uplink timing offset tracking, and beam management. By designing a universal SRS mechanism that performs multiple tracking and measurement functions through a single signal type, the system improves reliability of small data transfers without proportionally increasing device complexity, as the same SRS infrastructure supports diverse tracking requirements
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for configuring sounding reference signals (SRS) resources for RRC inactive or idle UEs and multiplexing SRS with small data transmission on preconfigured uplink resources (PUR) An example method by a user equipment (UE) generally includes receiving signaling configuring the UE with SRS resources, QCL relationship, power control and timing advance information for SRS transmissions, and transmitting SRS in conjunction with one or more of the PUR occasions in accordance with the configuration and signaling.