Wireless sensor networks (WSNs) have wide applications in environmental monitoring, healthcare, and target tracking. They can sense, collect, and transmit monitoring data in real time and can be considered part of computing networks such as the Internet of Things (IoT) and cloud computing. The self-organization methods for application-oriented WSNs generally start with a specific network characteristic, highlighting one or more functions to ultimately establish the network's basic operating mode. Network self-organization can be approached from aspects such as address allocation, routing protocols, and topology control.
Sensor networks mainly consist of aggregation nodes and monitoring nodes. The network is sensitive to address information. While the entire network operates as a whole, only nodes in certain areas are active, while nodes in other geographical areas remain dormant. This situation is known as an "information minefield" environment. To address this environment, we will explore a network self-organization method, which involves three steps.
1. Network startup method
When the aggregation node receives the startup information, it issues a startup command. The startup can only be successful if the command frame sent by the aggregation node meets the requirements of nodes within a certain geographical area (such as [a, b]) and does not exceed the detection time of the sensor node. Otherwise, it enters a dormant state.
2. Assign MAC addresses to nodes
The communication ID between neighboring nodes is actually a MAC address. Using a signaling algorithm, at the start of the network, network address allocation nodes are configured, and only nodes that receive the signaling are allowed to allocate MAC addresses. The process is as follows:
For example:
If the addresses of a node's neighboring nodes are "0", "1", "00", "10", and "11", then the MAC address to be assigned to this node should be calculated starting from "0". When "01" is calculated, "01" should be selected as its MAC address. MAC addresses can be reused throughout the network, and address allocation satisfies equation (1).
After the current address allocation is completed, its address status is set to 1, and the signaling availability count is incremented by 1. This process is recursively executed. After the entire allocation process is completed, the signaling is returned to the initiating node.
3. Basic methods of data routing
After the monitoring node wakes up, it will perform monitoring and report its monitoring data. Since neighboring nodes have different MAC addresses, a contention-based MAC protocol, such as CSMA, can be used.
The entire network operates in a distributed manner. Each node, upon receiving monitoring information from a neighboring node, should consider the correlation between the data and its own monitoring information to perform a corresponding fusion operation, thereby reducing the node's data volume, before forwarding its monitoring data. The cost function for a node forwarding data is generally f = p + r, where p is the node's remaining energy and r is a measure of the node's communication distance during data forwarding.
The following simulation experiment will illustrate the above steps.
-Summarize-
The network operates under the drive of startup information from remote terminals. This self-organizing method allocates MAC addresses via unicast signaling and forwards data based on the criterion of minimum cost function among neighboring nodes. This method is suitable for "information mine"-like wireless sensor network environments and is simple and easy to deploy and operate.
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