Information and Communication Technologies (ICTs), through wireless communications and the Internet of Things (IoT) paradigm, are the enabling keys for transforming traditional cities into smart cities, since they provide the core infrastructure behind public utilities and services. However, to be effective, IoT-based services could require different technologies and network topologies, even when addressing the same urban scenario. In this paper, we highlight this aspect and present two smart city testbeds developed in Italy. The first one concerns a smart infrastructure for public lighting and relies on a heterogeneous network using the IEEE 802.15.4 short-range communication technology, whereas the second one addresses smart-building applications and is based on the LoRa low-rate, long-range communication technology. The smart lighting scenario is discussed providing the technical details and the economic benefits of a large-scale (around 3000 light poles) flexible and modular implementation of a public lighting infrastructure, while the smart-building testbed is investigated, through measurement campaigns and simulations, assessing the coverage and the performance of the LoRa technology in a real urban scenario. Results show that a proper parameter setting is needed to cover large urban areas while maintaining the airtime sufficiently low to keep packet losses at satisfactory levels.

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A non-terrestrial network (NTN), a term coined by the 3rd Generation Partnership Project (3GPP), refers to a network utilizing airborne or spaceborne payload for communication. The use of NTN has the potential of facilitating providing connectivity to underserved areas. This has motivated the work in 3GPP on evolving the fifth generation (5G) wireless access technology, known as new radio (NR), to support NTN. The broadband opportunities promised by NTN with low Earth orbit (LEO) satellites have attracted much attention, but the performance of LEO NTN using 5G NR has not been well studied.In this paper, we address this gap by analyzing and evaluating the throughput and capacity performance of LEO NTN. The evaluation results show that the downlink capacity of a LEO satellite in S band with 30 MHz bandwidth serving handheld terminal is about 600 Mbps and the downlink capacity of a LEO satellite in Ka band with 400 MHz bandwidth serving very small aperture terminal (VSAT) is about 7 Gbps. For a LEO NTN similar to the Kuiper project proposed by Amazon, we find that, due to the large cell sizes in the LEO NTN, the area capacity density is moderate: 1 -10 kbps/km 2 in the S band downlink and 14 -120 kbps/km 2 in the Ka band downlink depending on latitude.

Since the first generation of cellular networks was rolled out, the priority has been to improve the connectivity and capacity of densely populated areas, such as urban centers, whereas rural areas received less attention. The lower subscriber density of such areas makes it difficult to get a positive business case with current wireless technologies and current cost structures. Base stations are deployed more sparsely in rural areas and are typically shared by several operators and are thus not able to provide high-performance connectivity, compared to urban areas, resulting in a connectivity gap. Third Generation Partnership Project (3GPP) is currently introducing Non-Terrestrial Networks (NTN) in 5G NR scope with Release 17 for broadband services, and this development will likely continue in 6G networks. In parallel, Sparse Terrestrial Networks (STN) using high towers and large antenna arrays, are being developed to deliver very long transmission ranges. In this paper we discuss the characteristics and the expected performance of networks based on satellites or terrestrial large cell networks, in relation to the traffic density and required infrastructure, with a focus on remote and sparsely populated areas. The two solutions are found to deliver in complementary traffic and partly different use case scenarios.