WLAN Power Saving via Doze State Indicators in TXOP
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Solution Overview
Problem
Next-generation WLAN systems supporting MU-MIMO transmission require an effective method for power saving in non-AP STAs to avoid unnecessary power consumption, as they need to maintain an awake state even when no data is transmitted to them, affecting overall throughput.
Innovation Solution
A method where non-AP STAs acquire a TXOP from the AP, receive a power saving indicator, and enter a doze state during the TXOP if not part of the transmission target group or if no spatial streams are allocated, using the VHT-SIGA field in PPDU to include group IDs and power saving indicators, allowing selective operation in sleep mode within the TXOP duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-AP STAs maintain an awake state during TXOP to receive potential data transmissions, then data reception reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic state transition for non-AP STAs, allowing them to switch between awake and doze states based on real-time transmission conditions. The STA monitors whether it is a target STA for upcoming data transmissions and adjusts its operational state accordingly, making the system adaptable to varying communication requirements while optimizing power consumption.
Solution Approach 2:
The non-AP STAs autonomously determine their own operational state (awake or doze) based on information received from the AP about transmission targets. Each STA independently evaluates whether it needs to remain awake to receive data or can enter doze state to save power, without requiring continuous polling or control from the AP, thus enabling self-service power management.
2Use of energy by moving object
If non-AP STAs enter doze state to save power, then power consumption is reduced, but network responsiveness deteriorates
Solution Approach 1:
The AP transmits information about target STAs and transmission timing in advance before the actual data transmission. This allows non-AP STAs to proactively determine whether they need to wake up for upcoming transmissions and prepare accordingly. By having this advance notice, STAs can enter doze state confidently knowing they will wake up in time to receive their data, maintaining network responsiveness while saving power.
3Reliability
If all non-AP STAs remain awake during TXOP to ensure data reception, then data delivery reliability is improved, but overall network throughput decreases
Solution Approach 1:
The patent applies different operational states to different non-AP STAs based on their individual needs. Instead of requiring all STAs to remain awake, only the target STAs (those for which data is actually being transmitted) maintain an awake state. Non-target STAs are allowed to enter doze state. This localized differentiation ensures that data delivery reliability is maintained for receiving STAs while improving overall network throughput by reducing unnecessary power consumption and interference from non-receiving STAs.
Data Source
AI summary
A method and a wireless apparatus for power saving in a wireless local area network are discussed. The method according to an embodiment includes receiving a frame including a signal field from a transmitting device. The signal field includes a number indicator and a power saving indicator. The number indicator indicates a number of spatial streams for a corresponding recipient, and the power saving indicator indicates that the transmitting device allows the wireless device to enter a doze state during a transmission opportunity (TXOP). The method further includes entering the doze state until the end of the TXOP if the power saving indicator indicates an allowance of entering the doze state during the TXOP, and the number of spatial streams to be received by the wireless device is equal to zero.