Beam-Swept Wakeup Signals for Low-Power mmW Beam Management
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Solution Overview
Problem
In mmW wireless communication systems, UEs experience high power consumption due to frequent attempts to decode beamformed PDCCH transmissions and prolonged wake-up periods, exacerbated by high path losses, which are inefficient and drain battery life.
Innovation Solution
A base station transmits a set of beam-swept wakeup signals, allowing the UE to monitor and select optimal beams, followed by refined beam management for efficient wake-up and data transmission, reducing the need for full PDCCH decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE attempts to decode beamformed PDCCH transmissions multiple times to mitigate high path losses, then the reliability of data reception is improved, but the power consumption at the UE increases significantly
Solution Approach 1:
The base station performs preliminary beam sweeping to identify suitable transmit beams before data transmission. The gNB transmits beamformed reference signals (e.g., CSI-RS) in advance, allowing the UE to measure and report channel quality indicators (CQI) for different beams. This preliminary beam identification and selection process enables subsequent data transmissions to use pre-determined optimal beams, reducing the need for multiple decoding attempts and thereby lowering UE power consumption while maintaining reliable reception
2Reliability
If the UE wakes up for a longer time period to receive and decode PDCCH transmissions and allow for beam management, then the reliability of beam selection is improved, but the power consumption at the UE increases
Solution Approach 1:
The beam management process is segmented into distinct phases: (1) beam sweeping phase where the gNB transmits reference signals on multiple beams, (2) measurement phase where the UE measures signal quality on each beam, and (3) reporting phase where the UE reports CQI for selected beams. This segmentation allows the UE to wake up only for the necessary duration to perform measurements and reporting, rather than remaining awake for extended periods, thus reducing power consumption while ensuring reliable beam selection through systematic evaluation of multiple beams
3Reliability
If the base station beam sweeps PDCCH transmissions to mitigate high path losses, then the signal quality at the UE is improved, but the complexity of the transmission system increases
Solution Approach 1:
The base station implements periodic beam sweeping, where a set of beams is systematically transmitted in a repeating sequence. During each beam sweeping period, the gNB transmits reference signals on different beams in a predetermined pattern. This periodic structure simplifies the transmission system by using regular, predictable patterns rather than complex adaptive beam management, while still achieving improved signal quality through systematic coverage of all necessary beam directions over each period
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. A access network entity may initiate a beam management procedure, including reference signal transmission to a user equipment (UE) and receive beam training. A access network entity may configure a UE to monitor a set of beams for reference signals. Based on the received reference signals, the UE may optionally select one or more transmit beams for wakeup signal reception, and may transmit an indication of the selected beams to the access network entity. The access network entity may transmit a wakeup signal over the originally configured or the UE-selected transmit beams to initiate wake-up procedure at the UE. The access network entity and UE may subsequently perform a refined beam management procedure, providing a refined reference signal transmission from the access network entity. Based on the received transmission, the UE may select a refined beam for downlink transmissions.