The introduction of fifth-generation (5G) mobile networks leads to an increase in energy consumption and higher operational costs for mobile network operators (MNOs). Consequently, the optimization of 5G networks’ energy efficiency is crucial, both in terms of reducing MNO costs and in terms of the negative environmental impact. However, many aspects of the 5G mobile network technology itself have been standardized, including the 5G network slicing concept. This enables the creation of multiple independent logical 5G networks within the same physical infrastructure. Since the only necessary resources in 5G networks need to be used for the realization of a specific 5G network slice, the question of whether the implementation of 5G network slicing can contribute to the improvement of 5G and future sixth-generation networks’ energy efficiency arises. To tackle this question, this review paper analyzes 5G network slicing and the energy demand of different network slicing use cases and mobile virtual network operator realizations based on network slicing. The paper also overviews standardized key performance indicators for the assessment of 5G network slices’ energy efficiency and discusses energy efficiency in 5G network slicing lifecycle management. In particular, to show how efficient network slicing can optimize the energy consumption of 5G networks, versatile 5G network slicing use case scenarios, approaches, and resource allocation concepts in the space, time, and frequency domains have been discussed, including artificial intelligence-based implementations of network slicing. The results of the comprehensive discussion indicate that the different implementations and approaches to network slicing pave the way for possible further reductions in 5G MNO energy costs and carbon dioxide emissions in the future.

The Internet of Things (IoT) has a lot to offer and contribute to the retail industry, from the innovations in retail store experience to the increased efficiency in the store management and supply chain optimization. On its way to real-world applications, Radio Frequency IDentification (RFID) became the main enabler for the final IoT deployment. However, to improve the technology performance even further, it is important to overcome the fundamental limitations of its physical layer and, consequently, to better understand how to use the technology in an optimal way. The analysis provided in this paper employs the simulation/measurement study on RFID technology advancement and the influence of radio propagation in a realistic model of the retail environment. The results are provided for different types of the retail layouts and materials that influence tag responsiveness.

The development of UHF RFID technology has reached significant performance advancement in the last 20 years. Both tags and readers are now improved with better sensitivity levels providing a potential for achieving greater tag read ranges. However, the performances of the technology are also limited by complexity and electromagnetic (EM) properties of the environment in which the system operates. The aim of this contribution is to evaluate how well the state-of-the-art UHF RFID systems behave in an actual retail store environment rather than in a controlled anechoic setting. An extensive empirical study is performed and data for the performance analysis are collected from both a commercial reader and an USRP-based sniffer. It is shown that physical and MAC layer should be considered cooperatively in order to improve the overall system performance. Specifically, although the tag responsiveness depends on the products’ EM properties as well as the number of products and their relative position in the basket, still the appropriate reader mode of operation can ensure a reliable and stable reading process. For the item identification and localization in the smart IoT stores, the EM properties of retail products should be taken into account in the data classification.

On the way from the Internet of things (IoT) to the Internet of underground things (IoUT) the main challenge is antenna design. The enabling technologies still rely on simple design and low cost, but the systems are more complex. The LoRa-based system combined with a machine learning approach can be used for the estimation of soil moisture by using signal strength data, but for the improvement of the system performance we propose the optimization of the antenna for underground use. The soil properties are frequency-dependent and varying in time, which may cause variations in the signal wavelength and input impedance of the antenna underground. Instead of using wideband antenna design or standard helical antenna provided in LoRa module, which are typical in the IoUT research community for communication links, we propose a narrow-band antenna design for the application in soil moisture sensing. It is shown that the approach of simply matching the antenna buried in dry sand can provide a substantial signal level difference, ranging from approximately 10 dB (achieved by proof-of-concept measurements) to as much as 40 dB (calculated by a full wave simulator) in reflection coefficient when the moisture content is being increased by 20%. This can ensure more reliable radio sensing in novel sensorless technology where soil moisture information is extracted from the signal strength of a transmitting device.

The capabilities of electrically small spherical helical antennas for wireless power transmission at small and moderate distances are analyzed. Influence of design on antenna radiation resistance, efficiency, and mode ratio is examined. These are the factors that, according to the theoretical considerations depicted herein, govern the maximum transfer performances. Various designs and configurations are considered for the purpose, with accent on small-size receivers suitable for implementation in powering common-sized gadgets. It is shown that spherical helix design is easily manipulated to achieve a reduced antenna size. Good radiation characteristics and impedance match are maintained by multiple-arm folded antenna design and by adjusting the separation between the arms.

The article presents an example of satellite propagation modeling, applying the radio channel transfer function analysis as described and experimentally verified in scientific literature. The simulation of a satellite radio channel is executed by employing "ray tracing" and the uniform geometric theory of diffraction-based method for an assumed urban and suburban environment and different polarizations. Derived results regarding the channel transfer function are analyzed via a simulation of the wideband propagation measurement system and the Fourier transform procedures. It has been concluded that, contrary to ground cell radio system situations, where two-ray models usually suffice, a more detailed calculation should be considered for wideband satellite radio systems. Moreover, it is shown that the conclusions derived for the path loss and the delay spread depend not only on the specific propagation scenario, but also on the building permittivity.