STA Power Save Mode Probe Request Timing Synchronization
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Solution Overview
Problem
In Wireless Local Area Network (WLAN) systems, stations (STA) operating in power save mode face challenges with timing synchronization and system information updates, leading to potential power inefficiencies and service disruptions due to prolonged doze states causing timing deviations between local and global clocks.
Innovation Solution
The STA actively synchronizes timing by transmitting a probe request frame to the access point (AP) with system information identification information, allowing for the detection and transmission of updated system information, thereby reducing unnecessary power consumption and ensuring timely system information acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the STA operates in the doze state for a longer time to save power, then power consumption is reduced, but timing synchronization and system information updates are compromised
Solution Approach 1:
The STA performs preliminary actions by periodically waking up to check for timing synchronization and system information updates before returning to the doze state. This ensures that the STA maintains necessary synchronization information in advance, avoiding the need to remain continuously awake while still ensuring reliable timing synchronization.
Solution Approach 2:
The STA implements periodic wake-up cycles to check timing synchronization and system information from the AP. By waking up at regular intervals rather than continuously, the STA maintains timing synchronization reliability while minimizing power consumption during the majority of time spent in the doze state.
2Reliability
If the STA wakes up frequently to check for system information updates, then timing synchronization is maintained, but power consumption increases
Solution Approach 1:
The STA performs partial checks for system information updates by comparing received information with stored information during wake-up periods. Rather than fully processing all possible updates, the STA only processes changes that are actually present, reducing the computational and energy overhead while still maintaining synchronization reliability.
3Loss of information
If the STA remains in the awake state to receive system information, then information acquisition is ensured, but power consumption increases due to extended awake time
Solution Approach 1:
The STA efficiently receives system information during brief wake-up periods by quickly checking for updates and immediately returning to the doze state if no updates are needed. This rushing through the information check process minimizes the time spent in the high-power awake state while ensuring that important system information is not missed.
Data Source
AI summary
Provided is a communication method by a station (STA) that operates in a power safe mode in a wireless LAN system. The method comprises: transmitting a probe request frame to an access point (AP), wherein the probe request frame includes system information identification information for identifying system information acquired by the STA; and receiving a probe response frame as a response to the probe request frame from the AP. The probe response frame includes a time stamp value related to the point of time of transmitting the probe response frame, and if it is determined, based on the system information identification information, that updated information which is not included in said acquired system information exists, the probe response frame further includes said updated information. Also provided is a communication method by an access point (AP) in a wireless LAN system. The method comprises: receiving a probe request frame from a station (STA), wherein the probe request frame includes information related to a wake-up duration time that is a time period in which the STA operates in an awake state; and transmitting a probe response frame to the STA as a response to the probe request frame. The probe response frame is transmitted within said wake-up duration time.