Opportunistic Beamforming Sounding for Low Latency Wireless
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Solution Overview
Problem
Wireless communication systems face challenges in maintaining low latency for applications like virtual reality and video streaming due to suboptimal beamforming channel estimates, which can expire or be affected by mobility and Doppler effects, leading to increased latency and potential communication failures.
Innovation Solution
An access point (AP) transmits sounding reference signals after data transmission during a service period to obtain a new beamforming channel estimate, allowing for improved communication reliability without sacrificing latency, and initiates another sounding procedure when the channel estimate becomes suboptimal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming channel estimates are updated periodically before data transmission, then communication reliability is improved, but latency increases due to additional signaling overhead
Solution Approach 1:
The patent inverts the conventional timing of beamforming updates by performing sounding procedures after data transmission instead of before. This allows the system to maintain current beamforming estimates for immediate data transmission (avoiding latency) while still updating channel information for future service periods (maintaining reliability). The AP transmits sounding reference signals during the same service period after data, and the STA provides feedback in the next service period, effectively decoupling the timing of reliability updates from data transmission timing.
2Reliability
If beamforming channel estimates are updated frequently, then communication reliability is improved, but system overhead increases
Solution Approach 1:
The patent implements dynamic beamforming update timing based on actual channel conditions rather than fixed periodic updates. The system monitors whether the current beamforming estimate remains satisfactory for the next service period using criteria such as timer expiration, mobility status, and Doppler effect measurements. Updates are performed only when necessary, adapting the update frequency to the actual channel stability and service requirements, thereby reducing unnecessary overhead while maintaining reliability when needed.
Solution Approach 2:
The system changes the timing parameter of beamforming updates from a fixed pre-transmission schedule to a flexible post-transmission schedule. By changing when the sounding procedure occurs (after rather than before data transmission) and conditionalizing it on channel estimate validity parameters, the system reduces overhead by eliminating redundant updates while maintaining reliability through timely updates when channel conditions deteriorate.
3Loss of time
If beamforming channel estimates are maintained for multiple service periods, then latency is reduced, but communication reliability deteriorates due to channel changes from mobility and Doppler effects
Solution Approach 1:
The patent implements a feedback mechanism where the STA monitors the validity of the beamforming channel estimate received from the AP and provides feedback in the next service period. The feedback includes information about whether the channel estimate remains satisfactory, based on measurements of mobility status, Doppler effect, and timer expiration. This feedback loop allows the AP to determine whether to perform another sounding procedure, enabling the system to maintain beamforming estimates across multiple service periods (reducing latency) while detecting and responding to channel changes (maintaining reliability).
Solution Approach 2:
The system performs preliminary assessment of channel estimate validity by checking timer expiration, mobility status, and Doppler effect measurements before determining whether to update beamforming. This preliminary action allows the system to maintain existing beamforming estimates for multiple service periods when conditions are stable (reducing latency) while being prepared to update when channel changes are detected (maintaining reliability).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances communication reliability and maintains low latency by updating beamforming estimates as needed, ensuring satisfactory performance even with changes in mobility or Doppler effects, thus supporting stringent latency requirements for applications like virtual reality and video streaming.
Implementation Method 1
The AP may transmit sounding reference signals (SRSs) before or after data transmission during a given service period
Implementation Method 2
The AP may determine that a previous beamforming channel estimate (e.g., a compressed beamforming estimate (CBF)) that provides satisfactory performance for a current period (e.g., may be used to select a beam that provides reasonable throughout, has a reasonable error rate, has reasonable directionality alignment between the AP and the STA, etc.) may be suboptimal (e.g., unsatisfactory or results in degraded performance) for a next service period (e.g., due to expiration of a timer associated with the current beamforming channel estimate, mobility of the STA, Doppler effect of the STA, etc.)
Data Source
AI summary
Methods, systems, and devices for wireless communications for opportunistic sounding for low latency applications are described. An access point (AP) may communicate with one or more stations (STAs), and may communicate a control message indicating more than one periodic service periods for wireless communication with the one or more STAs. The AP may transmit, via a transmit beam, a data message during a first service period of the more than one periodic service periods based on a first compressed beamforming estimate (CBF) for the transmit beam being satisfactory for the first service period and transmit one or more sounding signals during the first service period after transmitting the data message based on the first CBF being suboptimal for a second service period that occurs after the first service period. The STA(s) may transmit, and the AP may receive, an indication of a second CBF based on the one or more sounding signals.