# Management of Distributed Renewable Energy Resources with the Help of a Wireless Sensor Network
## 3 System Description
### Link Scheduling  
Time Slotted Channel Hopping (TSCH) wireless network scheduling methods are classified as centralized or decentralized. Centralized scheduling approaches are frequently used to address the high-performance requirements of mission-critical applications. This necessitates the collection of global network and traffic data by a central entity, a procedure that takes time and adds to signaling overhead. In the centralized scheduling methods, the sink node, which serves as a central entity, is aware of the attributes of member (sensor) nodes in the TSCH network. With the centralized scheduling mechanism, a single point of failure at the sink node could cause a disruption of the entire network operation without prior notice. Compared with centralized scheduling, the decentralized scheduling algorithm offers greater scalability and is devoid of single-point failure, but it can result in more packet collisions. Different types of network topologies can be utilized for link transmission. For dense networks, tree topology is preferred as it provides enough scalability. A parent node generally has one or more child nodes and the rank of the parent node is higher than the child node. Furthermore, the parent node can be a hub node to child nodes. Figure 2 depicts the 6 TiSCH networks with 40 nodes. The parent node and its child node are up to 20 m apart. The member nodes in the 6 TiSCH network are allocated across a 60 m \(\times\) 60 m square area and the operating conditions are established based on [28]. Different factors such as transmitted power, wavelength, the frequency band for typical 6 TiSCH networks, and scale parameter for Rayleigh fading are set to 0.002 Watt (3 dBm), 0.125 m, 2.4 GHz, and 1. Each node in a slot frame can send a number of packets in the range of 1-3. The time inside a slot frame for all the connection transmissions by the proposed link scheduling method can be represented as:  
\[T_{t}=T_{IPN/M}+T_{O/S}+T_{B} \tag{1}\]  
where \(T_{t}\), \(T_{IPN/M}\), \(T_{O/S}\), and \(T_{B}\) are defined as the time taken by all the link communication, time spent measuring interference-plus-noise (IPN) and delivering measured data to the  
Figure 1: Power monitoring system based on WSN. sink node, time spent performing optimization techniques to assign priorities, and time required for all link broadcasts to ultimately reach the sink node. \(T_{IPN/M}\) is separated into a time allotment, \(T_{IPN}\) for estimating IPN and \(T_{M}\) for transmitting member node attributes. In the same way, \(T_{O/S}\) is also divided; \(T_{O}\) for performing optimization and \(T_{S}\) for sending priorities of member nodes [60]. The 6 TiSCH wireless communication within the dense network is executed in tree topology which enables the flexible scaling of WSN. At the point when a parent hub flops in activity with a specific child node, another parent node within the communication range is utilized. Data transmission and subsequent affirmation require a cell that is associated with timeslot offset and channel offset. In Figure 3, cell usage of the 6 TiSCH wireless network is described. Figure 3a depicts a 6 TiSCH wireless network with dense nodes in a tree topology. The rank of the sink node is set to 1 and the parent node and its child node are only 20 m apart. The TSCH employs a combination of frequency channel hopping and time-division multiple access (TDMA) to mitigate the effects of wireless interference and multi-path fading, and separates time into different slot frames. TSCH divides the total transmissions into a channel distribution/usage (CDU) matrix having the dimensions of time and frequency. Timeslot offset and frequency offset address each cell of the CDU matrix. Every action of the node, transmitting/receiving in each timeslot, is determined by the TSCH schedule. Wireless interference between concurrent transmissions is greatly influenced by the cell/action allocation mechanism of the TSCH schedule.