Upper-Layer UL Wakeup Signal Configuration for Paging Power Saving
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Solution Overview
Problem
The existing radio resource control (RRC) signaling and medium access control (MAC) behavior for uplink wakeup signals (WUS) in wireless communication networks are not well defined, leading to inefficiencies in power conservation during idle/inactive states.
Innovation Solution
Configuring user equipment (UE) and network operations for uplink wakeup signals (WUS) using system information blocks (SIB) to manage periodic or aperiodic UL WUS resources, with trigger conditions and sequence selection for UL WUS transmission, including PRACH preambles or new sequences, to optimize power saving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously monitors paging occasions to ensure reliable communication, then the reliability of message delivery is improved, but the power consumption increases
Solution Approach 1:
The patent implements discontinuous reception (DRX) cycles where the UE alternates between active monitoring periods and sleep periods. During DRX OFF durations, the UE skips monitoring paging occasions, reducing power consumption while maintaining acceptable message delivery reliability through periodic wake-ups at configured intervals.
Solution Approach 2:
The UE autonomously determines whether to monitor or skip paging occasions based on internal state and configured parameters. The device self-manages its monitoring behavior by evaluating conditions such as whether it has uplink data to send or needs to receive downlink data, enabling it to independently optimize power consumption without continuous network control.
2Use of energy by moving object
If the UE transmits UL WUS to notify the gNB of its presence, then the power saving is improved, but the device complexity increases due to undefined RRC signaling and MAC behavior
Solution Approach 1:
The patent defines specific parameters for UL WUS operation including drx-HARQ-RTT-TimerUL, drx-ULRetransmissionTimer, and drx-OnDurationTimer. These parameters control the timing and behavior of UL WUS transmission and processing, providing a standardized mechanism that reduces implementation complexity while enabling power saving functionality.
Solution Approach 2:
The UL WUS acts as an intermediary signal between the UE and gNB, enabling the UE to notify the network of its presence without establishing a full RRC connection. This intermediate signaling mechanism allows power-saving operation by avoiding the overhead and complexity of complete connection establishment while still maintaining network awareness.
3Reliability
If the gNB continuously transmits paging signals to ensure all UEs are reached, then the coverage and reliability are improved, but the network energy consumption increases
Solution Approach 1:
The gNB implements discontinuous transmission (DTX) of paging signals aligned with UE DRX cycles. Instead of continuous paging transmission, the gNB transmits paging only during configured ON durations when UEs are expected to be monitoring, reducing network energy consumption while maintaining reliable delivery to all UEs that are awake to receive.
Solution Approach 2:
The gNB configures DRX parameters and paging occasions in advance before actual paging transmission. This preliminary configuration allows both the gNB and UE to synchronize their active periods, enabling the gNB to transmit paging signals only when needed and at predictable times, optimizing energy usage while ensuring reliable delivery.
Data Source
AI summary
A user equipment (UE) configured to receive a configuration from a network cell for an uplink (UL) wakeup signal (WUS) resource, determining to transmit a UL WUS when a condition is triggered, the condition comprising the UE being present in an upcoming paging occasion (PO) or beam or the UE intending to receive a paging early indication (PEI), select a sequence for transmitting the UL WUS, the sequence comprising a physical RACH (PRACH) preamble reserved for UL WUS or a sequence introduced for UL WUS and transmit the UL WUS.