DRX Uplink Reference Signaling for Fresh Channel Measurements
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Solution Overview
Problem
In wireless communications systems, discontinuous reception (DRX) operations lead to stale channel measurements due to UEs transitioning to a lower power mode, resulting in degraded communications until fresh measurements are obtained, which is particularly problematic for high reliability and low latency communications.
Innovation Solution
Uplink reference signals, such as SRS, are transmitted during inactive durations of the DRX cycle in the absence of a wakeup indication, allowing for efficient beam management and maintenance of directional communication beams, even when the UE is not explicitly signaled to wake up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If UE transitions to lower power mode during DRX inactive duration, then power consumption is reduced, but channel measurements become stale and communication quality degrades
Solution Approach 1:
The UE performs uplink reference signal transmissions during the inactive duration as a preliminary action before the active duration begins. This allows the base station to obtain fresh channel measurements in advance, eliminating the need for the UE to wake up solely for channel measurement purposes and enabling immediate use of updated channel state information when communications resume.
Solution Approach 2:
The patent establishes a continuous mechanism where the UE periodically transmits uplink reference signals both during inactive durations (when no wakeup indication is received) and during active durations. This continuity ensures that channel measurements are continuously updated without interruption, maintaining measurement freshness while the UE remains in power-saving mode.
2Measurement precision
If UE transmits uplink reference signals during inactive duration without wakeup indication, then channel measurements are updated, but power saving benefits are reduced
Solution Approach 1:
The UE autonomously determines when to transmit uplink reference signals by monitoring its own wakeup indication status. When no wakeup indication is received during the inactive duration, the UE self-initiates reference signal transmissions to maintain channel measurement freshness. This self-service mechanism ensures the UE only transmits reference signals when necessary, balancing measurement updates with power conservation.
3Use of energy by moving object
If UE waits for wakeup indication before transmitting reference signals, then power consumption is minimized, but communication latency increases
Solution Approach 1:
The UE performs reference signal transmissions as a preliminary action during the inactive duration before the active duration begins. By initiating these transmissions in advance, the base station receives and processes the reference signals before the UE needs to resume full communication operations, thereby reducing the latency that would otherwise occur while waiting for a wakeup indication and subsequent reference signal transmission.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described in which a user equipment (UE) may be configured for discontinuous reception (DRX) operations using wakeup signals. The UE may monitor periodic wakeup signal occasions for wakeup signals and, in the event that the UE detects a wakeup indication that the UE is to initiate an active duration, the UE may power on transmit/receive circuitry for communications with a base station. In an absence of receiving the wakeup indication, the UE may be configured to transmit an uplink reference signal (e.g., a sounding reference signal) to the base station in an inactive duration of a DRX cycle in some cases. The uplink reference signal may be measured at the base station and used to determine one or more parameters for subsequent communications with the UE.