1. Introduction

Research and development work in the field of electrical engineering and other technical sciences has always aimed to develop more powerful devices with ever-increasing processor power and responsiveness (Sodnik et al. 2014). A reduction in the size of modern devices and the extension of their use to new fields and environments has been a significant design trend in recent years. Mobile devices enabling various types of communication with and access to important sources of information in mobile environments constitute an important segment of modern electronics. Mobile devices can be general-purpose laptops, notebooks, tablets or smartphones, or can be highly-adapted purpose-built devices found in vehicles and other means of transport. In terms of the range of functionalities and the corresponding software, the majorities of advanced mobile devices are becoming very similar to traditional desktop computers, and thus allow for continuous upgrades and the addition of new applications.