## 1 Introduction
TASA uses two graph procedures in its algorithm: graph coloring and graph matching. Graph coloring is used to save the use of channel offset, while graph matching is used to avoid duplex conflict. An explanation of the duplex conflict will be given in the next section. To get the minimum duty cycle, in each timeslot period, TASA will create a schedule based on the graph-matching principle. The schedule determines which nodes can be active and passive at each timeslot. Active nodes will carry out transmit or receive activities, while passive nodes will enter into idle or sleep conditions. The TASA procedure, which carries out a graph-matching process at each timeslot period to determine the transmit, receive, and sleep schedules of each node, will need more time to produce scheduling decisions with increasing network size. This is not a desirable condition, because the number of nodes in the IoT era will be very large. Figure 1: 6 TiSCH protocol stack. 6 TiSCH, Internet protocol version 6 (IPv6) over the time synchronized channel hopping (TSCH) mode of IEEE802.15.4e. In order to increase the speed of the link-scheduling algorithm in generating scheduling decisions, our previous work [12] proposed a scheduling algorithm that has higher speed than TASA. This algorithm is called the Iman-Ramli bursty transmission scheduling algorithm (IRByTSA), which is an upgraded version of the Iman-Ramli TASA algorithm (IR-TASA) [13]. IRByTSA is proven to be faster than TASA in generating link-scheduling decisions, ranging from 2.5 to 7.14 times for network sizes from 10 to 100 nodes. In [12], IRByTSA was tested for its performance and was implemented in a text-based tool created using the C and C++ programming languages. As a development of IRByTSA, this research has created a new tool called the TSCH link-scheduling visualization and data processing or abbreviated as TLS-VaD. This name is based on the tool's two facilities: a visualization of the workings of the scheduling algorithm and the output data, which shows the algorithm's performance. TLS-VaD was created specifically for developing a centralized link-scheduling algorithm on the TSCH network. This new tool uses the concept of a graphical user interface (GUI), which was created by using the PHP and JavaScript programming languages. The use of a GUI-based tool makes it easier to develop scheduling algorithms. As a research support tool, TLS-VaD was developed as an alternative to existing simulators because those simulators have not provided sufficient support for the development of a centralized scheduling algorithm for TSCH networks. The related existing simulators are NS-3, OPNET, and NS-2. Many factors can affect the performance of scheduling algorithms on a communication network, including signal interference, network congestion, data transmission failure, and so on. As this research concentrates on the duty cycle parameters and the speed of generating scheduling decisions, the TLS-VaD development will use the following limitations and assumptions:  
1. The server knows the overall network conditions, such as the network topology, the number of nodes in the network, and the number of packets waiting in the queue of each network node. 2. Each node can synchronize itself to the network and know the schedule to transmit, receive, and sleep, based on information sent by the server. 3. At the beginning of each slotframe, each node generates one packet of data regularly to be sent to the master node. 4. Each node will do a bursty transmission when it gets its turn to transmit, so that after the transmit process, the queue in the node becomes empty. 5. There is no interference and packet loss. Henceforth, this paper will be organized according to the following research framework.