Wireless Sensor Network Delayed Reply Mechanism
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Solution Overview
Problem
Existing wireless remote sensor networks face a trade-off between update rate and battery life, where high update rates for safety-critical applications lead to increased power consumption and reduced battery life, especially in systems like gas sensors that require rapid reporting of hazardous gas levels.
Innovation Solution
Implementing a wireless sensor network with sensor units that introduce a deliberate delay in responding to interrogation messages under normal conditions, allowing for quicker transmission of alarm messages when an alarm condition is met, thereby extending battery life while maintaining the ability to report critical data promptly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high update rate is used to quickly report alarm conditions, then the reporting speed is improved, but the power consumption increases and battery life is reduced
Solution Approach 1:
The sensor unit dynamically adjusts its response timing based on the detected condition. Under normal conditions, it uses a long deliberate delay (more than 80% of period T) to conserve energy. When an alarm condition is detected, it immediately transmits the reply message within the last 20% of the period, achieving fast reporting without continuous high power consumption.
Solution Approach 2:
The system changes the temporal parameter of message transmission based on the detected state. The reply message transmission time is shifted from the end of the deliberate delay (normal state) to within the last 20% of the period (alarm state), allowing the system to adapt its power consumption and reporting speed to the actual operational requirements.
2Duration of action of moving object
If a low update rate is used to conserve battery power, then battery life is extended, but the ability to quickly report alarm conditions is reduced
Solution Approach 1:
The sensor unit prepares for potential alarm conditions by continuously monitoring the sensed parameter during the deliberate delay period. The alarm detection mechanism is always active and ready, so when an alarm condition occurs, the system can immediately transmit the alert without waiting for the next scheduled update, ensuring reliable alarm detection while maintaining low power consumption.
3Loss of information
If the sensor unit transmits reply messages frequently under normal conditions, then data availability is improved, but power consumption increases
Solution Approach 1:
The interrogating node transmits interrogation messages periodically with period T, and the sensor unit responds accordingly. This periodic interaction ensures that data is available when needed while allowing the sensor unit to remain in a low-power state between interrogations, optimizing the balance between data availability and power consumption.
Data Source
Figure 1
Figure 2~3
AI summary
A wireless sensor network comprises at least one sensor unit (2) which comprises a sensor for sensing a parameter and at least one interrogating node (8). The interrogating node (8) is arranged to transmit an interrogation message periodically to said sensor unit (2) and to receive a reply message from said sensor unit (2). The sensor unit (2) is arranged to transmit said reply message after a predetermined deliberate delay unless the sensor unit (2) determines that an alarm condition has been met, in which case the sensor unit (2) is arranged to transmit said reply message before the end of the deliberate delay.