Sensor Network Synchronization via Base Station Time Reference
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Solution Overview
Problem
Traditional methods for time stamping and synchronizing sensor nodes in wireless sensor networks face challenges due to energy constraints and the need for high computing power, especially in dynamic environments where maintaining constant time intervals is difficult, and dynamic adjustments of sensor sampling rates complicate the process.
Innovation Solution
A sensor node and base station system that uses a digital time counter and light-based synchronization signals to restart the counter, allowing for efficient time stamping and synchronization with minimal energy and computational effort, using high-frequency or infrared transmitters and solar cells for energy harvesting, enabling precise temporal and spatial allocation of measurement data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time stamping methods are used with individual node clocks, then each sensor node can independently record measurement times, but the clocks differ in physical properties and environmental conditions causing synchronization errors and requiring significant computing power for correction
Solution Approach 1:
The patent extracts the time reference function from individual node clocks and centralizes it in a base station that generates and transmits synchronization signals. This removes the complexity of managing multiple independent clocks with different physical properties, as all nodes now reference a single centralized time source.
Solution Approach 2:
The base station acts as an intermediary that provides a common time reference to all sensor nodes. Instead of nodes directly comparing and synchronizing with each other, they all receive timing information from the base station, simplifying the synchronization architecture.
2Measurement precision
If frequent synchronization signals are transmitted to maintain time accuracy, then time stamping precision is improved, but energy consumption increases due to limited energy reserves of sensor nodes
Solution Approach 1:
The base station transmits synchronization signals at periodic intervals rather than continuously. This allows nodes to maintain accurate time stamps while consuming less energy, as they can enter low-power states between synchronization events and only wake to receive timing updates.
Solution Approach 2:
Sensor nodes are equipped with local time counters that continue counting between synchronization signals. Nodes independently maintain time records using their own counters, only needing to periodically synchronize with the base station, reducing the frequency of active communication and energy consumption.
3Adaptability or versatility
If dynamic adjustments of sensor sampling rates are implemented to adapt to changing conditions, then measurement adaptability is improved, but time interval constancy becomes difficult to maintain and requires significant software and hardware effort
Solution Approach 1:
The base station transmits synchronization signals that include timing information for upcoming measurement events. Nodes use this advance timing information to prepare for measurements at the correct times, even when sampling rates change dynamically, without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The system uses feedback from the base station's synchronization signals to adjust node timing. The base station monitors and provides correction information to nodes, allowing dynamic sampling rate adjustments while maintaining overall time coordination through continuous feedback loops.
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 reduces the complexity and energy requirements for synchronization, allowing for accurate and efficient time stamping and synchronization of sensor nodes with low computational effort, suitable for applications like spacecraft where energy efficiency is crucial.
Implementation Method 1
a receiving unit for receiving wirelessly transmitted signals
Implementation Method 2
a transmitting unit for transmitting respective measurement signals wirelessly
Data Source
Figure 1
AI summary
A sensor node (20, 30, 40) according to the invention for a sensor network (100) comprises at least one sensor, at least one node receiver (21, 31, 41), a node timer (22, 32, 42), and at least one node transmitter (24, 34, 44). A base station (10) according to the invention for a sensor network (100) comprises at least one base transmitter (11) for wirelessly transmitting synchronization signals (S), a reference clock (13), and at least one base receiver (14a, 14b). The node timer (22, 32, 42) is restarted each time a synchronization signal is received. Measurement signals sent by the sensor node or received by the base station each comprise at least one measured value with an associated counter value of the node timer (22, 32, 42) that is current at the time of acquisition. From this, the base station determines a respective acquisition time of the measured values in relation to the reference clock (13).Furthermore, a sensor network (100), a time-stamping method and a synchronization method for sensor nodes of a sensor network (100) are disclosed.