# PSON: A Serialization Format for IoT Sensor Networks
## 1 Introduction
Moreover, because it is a standardized technology, LPWAN is supported by a global ecosystem that allows interoperability between different market players and production scales of these solutions, which will reduce the cost of the technology once it is consolidated [12]. As discussed above, the massive growth of IoT solutions will require the use of devices with limited capabilities [13; 14]. Although technological advancement is ongoing, due to the limited resources available in a typical sensor device, and in order to achieve lower power consumption at the nodes, it is important to reduce the amount of data exchanged. Various initiatives have been developed to improve energy consumption in sensor networks. Some of them aim to optimize energy by designing routing protocols [15; 16]. Other work has focused on the development of Wireless Power Transfer (WPT) technology [17; 18; 19; 20; 21] or Energy Harvesting (EH) [22]. However, the focus of this research work is on the efficient transfer of data from devices to the server-side. In this way, the processing power, available memory, and battery life of IoT devices, which are mostly limited in these aspects [23; 24], will be optimized. For the transmission of information in both directions, that is, between the device and the server, serialization formats are used. Serialization is the process of translating data structures or object states into a format that can be transmitted and reconstructed later. Therefore, serialization is the conversion of an object into a sequence of bytes, whereas deserialization is the reconstruction of an object from a sequence of bytes. Serialization/deserialization processes are critical for devices with limited on-board energy, such as those in an IoT network. The smaller the size of the serialized object and the shorter the execution time involved, the more efficient the format. Any reduction in processor time for transaction serialization/deserialization contributes to an increase in the deployed lifetime of an IoT device. There are a number of different serialization formats, as is discussed further below. In IoT environments, where many devices are expected to be connected to the server, the importance of selecting a serialization format is vital in order to reduce overheads (measured as memory and bandwidth usage) [25]. Although the selection of the message protocol [25; 26] is also relevant in the communication system, the focus of this paper is the presentation of a new serialization format called PSON [27]. The main goal of PSON is to define a serialization format efficiently in terms of total serialization time and bandwidth required to transmit arbitrary data payloads. The main problem with other encoding technologies is that they were not specifically designed thinking in the IoT ecosystem, both for servers to allow them to scale better while decoding massive IoT sensor data, and for sensors to last long when powered by batteries. This way, some existing methods are quite efficient for reducing the payload size, but they increase the total serialization/deserialization complexity in terms of processing power, especially for a small microcontroller. PSON is then focused on providing a balance between serialization time and generated payload size. PSON is used in the Thinger.io Cloud Platform [28]. Thinger.io is an open-source platform with capabilities for the collection, management, and analysis of a huge amount of heterogeneous sensor data. The use of PSON provides optimization in terms of execution time, channel utilization, and power consumption compared to the most common methods used in IoT environments. The aim of this paper is to describe this new serialization format and assess its performance compared to the most widely used formats. The remainder of this article is organized as follows: Section 2 introduces the main aspects and the information sources of the data serialization formats that are analyzed and compared in the presented research.