Adaptive Wireless Scan Interval for Low Power Device Discovery
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Solution Overview
Problem
Existing wireless communication methods for battery-powered electronic devices face high power consumption during device discovery due to contention for channels and the need for individual discovery of multiple devices, especially when many devices are attempting to find each other, which exceeds the low power-consumption targets.
Innovation Solution
An electronic device determines a sequence of wireless channels to scan for advertising frames, alternating between scanning and transmitting on a 'home' channel, with scanning intervals set based on transmit intervals and an overhead value, allowing efficient detection of nearby devices with reduced power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive scanning with fixed dwell time is used to detect advertising frames, then device discovery capability is maintained, but power consumption increases significantly when multiple devices are attempting to discover each other
Solution Approach 1:
The patent applies dynamics by making the scanning interval adaptive rather than fixed. The electronic device dynamically adjusts the scanning interval based on the detected advertising frame interval, allowing the system to optimize power consumption while maintaining reliable device discovery. The scanning interval is set to match the advertising frame interval plus overhead, creating a dynamic adaptation mechanism that responds to actual channel conditions.
Solution Approach 2:
The patent changes the parameter of scanning interval from a fixed value (110-120 ms) to a variable parameter that is determined based on the advertising frame interval detected in the channel. This parameter change allows the system to adjust scanning frequency according to actual device advertising patterns, reducing unnecessary scanning when advertising frames are sparse and thereby lowering power consumption.
2Adaptability or versatility
If multiple devices perform passive scanning simultaneously on the same channels, then all devices can discover each other, but channel contention increases leading to longer discovery times and higher power consumption
Solution Approach 1:
The patent applies preliminary action by having devices transmit advertising frames at predetermined intervals before scanning begins. This allows scanning devices to detect the advertising frame interval in advance and configure appropriate scanning intervals, ensuring that discovery can proceed efficiently without channel contention delays. The preliminary transmission of advertising frames sets up the conditions for successful subsequent scanning.
Solution Approach 2:
The patent implements feedback by using the detected advertising frame interval to adjust the scanning interval. The system continuously monitors the channel for advertising frames, measures their interval, and uses this information to optimize scanning timing. This feedback mechanism allows devices to adapt to the presence of multiple transmitting devices and adjust scanning frequency to minimize channel contention and discovery time.
3Use of energy by moving object
If radio is used sparingly to meet power targets, then power consumption is reduced, but the ability to detect devices in sleep states diminishes
Solution Approach 1:
The patent applies periodic action by having devices transmit advertising frames at regular, predetermined intervals rather than continuously. This periodic transmission creates predictable patterns that scanning devices can detect and synchronize with. By setting the scanning interval to match the advertising frame interval plus overhead, the system ensures that scanning occurs at optimal moments when advertising frames are likely to be present, maintaining detection reliability while keeping radio usage sparse and power consumption low.
Data Source
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AI summary
An electronic device performs a scan of each wireless channel in a sequence of wireless channels to detect advertising frames transmitted from other electronic devices. When performing the scan, the electronic device waits for a next transmit time. After the next transmit time, the electronic device configures the electronic device to monitor a next wireless channel from the sequence of wireless channels. The electronic device then monitors the next wireless channel for the advertising frames for a scanning time interval, wherein a duration of the scanning time interval is set in accordance with one or more transmit times used for transmitting advertising frames on the wireless channels in the sequence of wireless channels. When wireless channels from the sequence of wireless channels remain to be scanned, the electronic device returns to wait for a next transmit time.