## 1 Introduction and State-of-the-Art
### Main Attributes of this Research  
Next, we will present the main elements that determine the orientation, structure and novelty of the presented research. An _object_ of this research is an extensive process of controlling massive data transfer from the SNEIoTD environment to a hub as a result of the interaction of the main mechanisms of the TCP. A _subject_ of this research includes the theory and methods of mathematical modelling, probability theory, queuing theory, and recovery theory. The _goal_ of this research is articulated as follows: to analytically determine the unified speed of information transfer from the SNEIoTD environment to a hub controlled by the main mechanisms of TCP, taking into account the specific features of this process. Our research objectives are:  
* to formalize the parametric space for an adequate representation of the research object;
* to formalize the concepts that characterize the features of the interaction of the main mechanisms of the TCP (Slow Start, Additive-Increase/Multiplicative-Decrase) when controlling massive data transfer from the SNEIoTD environment to a hub discretely and continuously;
* to formalize the information technology for calculating the TCP Window Size of both mentioned mechanisms and the \(<\)ssthresh\(>\) parameter;
* to implement a numerical experiment, the results of which will justify the effectiveness of the created mathematical apparatus. Now, let us state the _main contribution_ of the research. The IoT systems are designed for the collection of information. If an entire system of smart city traffic lights generates dozens of megabytes of traffic, and a high-quality video surveillance system alone generates gigabytes of traffic, ensuring its reliable transmission to the cloud using a wireless communication channel becomes a non-trivial task. This article proposes an idea to alleviate this constraint by introducing an additional hardware element into the classical \"sensor network\"--\"cloud\" structure (SNEIoTD, see Figure 1). To achieve maximum benefit from this proposal, the authors have suggested a mathematically founded TCP-based information technology for effective control of reliable transmission of massive traffic between a SNEIoTD and the edge of the cloud. This article proposes a mathematical model of the interaction of the main mechanisms of the TCP (Slow Start, Additive-Increase/Multiplicative-Decrease) in the form of a queuing system, which describes the process of reliable control of massive traffic from the SNEIoTD environment to a hub. As part of this model, a semi-Markov process is selected that describes the interaction of these mechanisms, locked to the definition of such a characteristic parameter as the unified speed of information transfer. As a result of recurrent analyses of the aforementioned process, a stationary distribution of an embedded Markov chain is determined. This made it possible to analytically describe the stationary distribution of the original semi-Markov process. The aforementioned stationary distribution analytical representation became the basis for the formalization of an accurate, computationally efficient information technology for calculating the TCP Window Size of both the previously mentioned mechanisms and the \(<\)ssthresh\(>\) parameter. In the following sections of the article, three main sections are highlighted. Section 2 introduces the parametric space that characterizes the interaction of TCP mechanisms in the process of traffic control from the SNEIoTD environment to a hub. The distribution function of the stochastic parameter TCP Window Size for the studied process was investigated. Elements of the research on the dynamic properties of the TCP Window Size stochastic parameter over time are also formalized. Section 3 is devoted to simulation modelling to demonstrate the information technology formulated in Section 2.2. Section 3 also provides empirical results on the example of the TCP Westwood+ protocol, which proves the functionality of the proposed mathematical apparatus.