Scalability and performance evaluation of DECT NR+ for IOT connectivity

Curso: 2024-2025 Director/Directora: Herrero Villalibre, Saioa Estudiante: Hernández Jauregui, Iker SCALABILITY AND PERFORMANCE EVALUATION OF DECT NR+ FOR IOT CONNECTIVITY MÁSTER UNIVERSITARIO EN INGENIERÍA DE TELECOMUNICACIÓN TRABAJO FIN DE MÁSTER Fecha: Bilbao, 17de febrero 2025 Supervisado y dirigido en destino por: Horst Hellbrück TECHNISCHE HOCHSCHULE LÜBECK DEPARTMENT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE TRABAJO FIN DE MÁSTER REALIZADO EN MOVILIDAD Hitzaurrea Tesi honek DECT NR+ teknologia aztertzen du, bere gaitasunen, errendimenduaren eta LPWAN teknologien panoramaren barruan duen posizioaren azterketan eta ebaluazioan zentratuz, eta 5G-rako diseinatutako erabilera-kasu berrietarako baldintzak betetzen diren aztertuz. NS3 eta MATLAB erabiliz egindako simulazioen bidez, ikerketak teknologiaren eskalagarritasuna ebaluatzen du. Baita ere, errendimenduaren azterketa sakona burutu da gailu bateragarrien erabilerari esker, errendimenduaren funtsezko parametroak probatzeko agertoki gidatuak diseinatuz, garatuz eta gauzatuz. Ebaluazio horien emaitzak teknologia hori diseinatu zen 5G erabilera-kasuetako baldintzekin konparatu dira, eta argiztapen adimendunerako erabilera-kasu bat garatu da Smart Cities-en testuinguruan, teknologiaren ahalmenak kontuan hartuta. Ikerketa honek DECT NR+ 5G ekosistemetarako bideragarria den LPWAN teknologia gisa ulertzen laguntzen du. Hitz gakoak: DECT NR+, LPWAN, 5G, NS3, MATLAB, argiztapen adimenduna, Smart Cities Resumen Esta tesis explora la tecnolog´ıa emergente Digital Enhanced Cordless Telecommunications New Radio + (DECT NR+), centr´andose en el examen y evaluaci´on de sus capacidades, rendimiento y posici´on dentro del panorama de las tecnolog´ıas de Red de ´ Area Amplia de Bajo Consumo (LP-WAN) y el cumplimiento de los requisitos para los nuevos casos de uso dise˜nados para 5G. A trav´es de simulaciones utilizando NS3 y MATLAB, el estudio eval´ua la escalabilidad de la tecnolog´ıa. Adem´as, se ha realizado un an´alisis exhaustivo del rendimiento con la primera generaci´on de dispositivos compatibles mediante el dise˜no, desarrollo y ejecuci´on de escenarios dirigidos para probar par´ametros clave de rendimiento. Los resultados de estas evaluaciones han sido comparados con los requisitos de los casos de uso 5G para los que fue dise˜nada esta tecnolog´ıa y se ha desarrollado un caso de uso espec´ıfico para iluminaci´on inteligente en el contexto de Smart Cities teniendo en cuenta las capacidades de la tecnolog´ıa. Esta investigaci´on contribuye al entendimiento de DECT NR+ como una tecnolog´ıa LP-WAN viable para los ecosistemas 5G. Palabras clave: DECT NR+, LPWAN, 5G, NS3, MATLAB, iluminaci´on inteligente, Smart Cities Abstract This thesis explores the emerging Digital Enhanced Cordless Telecommunications New Radio + (DECT NR+) technology, focusing the work in examining and evaluating its capabilities, performance, and position within the landscape of Low-Power Wide-Area Network (LP- WAN) technologies and the fulfillments of the requirements for the new use cases designed for 5G. Through simulations using NS3 and MATLAB, the study evaluates the scalability of the technology. Moreover, an extensive performance analysis with the first generation of compatible devices has been conducted by designing, developing, and executing targeted scenarios to test key performance parameters. The results of this evaluations have been compared to the requirements of the 5G use cases for this technology was designed for and a specific use case has been developed taking into account on what the technology o!ers. Based on the evaluation, a novel use case leveraging DECT NR+’s unique features was developed, showcasing its potential applications in smart lighting applications. This research contributes to the understanding of DECT NR+ as a viable LP-WAN technology for the 5G ecosystems. Keywords: DECT NR+, LPWAN, 5G, NS3, MATLAB, smart lighting, Smart Cities Contents List of Figures viii List of Tables x 1. Introduction 1 1.1. Motivation ..................................... 1 1.2. Goal......................................... 1 1.3. Organization .................................... 3 2. Background 4 2.1. Introduction..................................... 4 2.2. HistoryofDECTNR+............................... 4 2.2.1. 5G...................................... 5 2.3. Specifications.................................... 8 2.3.1. SystemArchitecture ............................ 9 2.3.2. Networking ................................. 9 2.3.3. PhysicalLayer ............................... 11 2.3.4. MACLayer................................. 16 2.3.5. Data Link Control and Convergence Layer . . . . . . . . . . . . . . . . 19 2.3.6. Co-existence ................................ 19 2.4. Comparisons .................................... 19 2.4.1. Introduction ................................ 19 2.4.2. LTE-M ................................... 20 2.4.3. NB-IoT ................................... 21 2.4.4. Bluetooth 5.3 Low Energy . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4.5. IEEE802.15.4 ............................... 22 2.4.6. LoRaWAN ................................. 22 2.4.7. Conclusions................................. 22 2.5. Summary ...................................... 26 3. Simulation and Modeling 27 3.1. Introduction..................................... 27 3.2. Network simulation - NS3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.3. Radio Planning - Matlab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.3.1. Transmitter................................. 32 3.3.2. Receiver................................... 32 3.4. Summary ...................................... 34 4. Evaluation of DECT NR+ technology 36 4.1. Introduction..................................... 36 4.2. Equipment ..................................... 37 4.2.1. nr9161 Development Kit . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.3. Networkevaluation................................. 39 4.4. RFEvaluation ................................... 41 4.4.1. Testscenario ................................ 41 4.4.2. Bandwidth ................................. 42 4.4.3. Timinganalysis............................... 43 4.4.4. Power transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.5. Performance evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.5.1. DataRate.................................. 46 4.5.2. Co-existence testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.5.3. Rangetesting................................ 52 4.5.4. Latency ................................... 53 4.6. Research....................................... 56 4.7. Summary ...................................... 60 5. Use cases 62 5.1. Introduction..................................... 62 5.2. URLLC ....................................... 62 5.3. mMTC........................................ 63 5.4. Smart Lighting solution for Smart Cities . . . . . . . . . . . . . . . . . . . . . 65 5.4.1. Practical implementation . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.5. Summary ...................................... 68 6. Conclusions 69 1. Appendices ..................................... 70 A. Collected data from the testing . . . . . . . . . . . . . . . . . . . . . . 70 B. Flow charts of the code developed for thesis . . . . . . . . . . . . . . . 76 Bibliography 79 List of Figures 2.1. Services that can be implemented on technological basis of 5G generation communicationnetworks. ............................. 6 2.2. Illustration of overall protocol stack architecture of DECT-2020 [21b]. . . . . 9 2.3. Formation of the clustered tree mesh network topology [21b]. . . . . . . . . . 11 2.4. Operating band numbering [21c] . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.5. Illustration of RF resource mapping [21c]. . . . . . . . . . . . . . . . . . . . . 14 2.6. DECT-2020 NR frame structure [21c]. . . . . . . . . . . . . . . . . . . . . . . 15 2.7. Illustration of Random Access transmissions [24]. . . . . . . . . . . . . . . . . 18 2.8. Example resource allocation with downlink and uplink resource assignment, with µ=1[24].................................... 18 2.9. Comparison of technologies based on their max data rates and range. . . . . . 24 3.1. NS3 simulation mesh network model . . . . . . . . . . . . . . . . . . . . . . . 30 3.2. NS3simulationresults............................... 31 3.3. Radio planning coverage result. . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.1. 3D visualization of a spectrogram while a DECT NR+ transmission. . . . . . 42 4.2. 2D visualization of the DECT NR+ spectrogram while two perf transmissions. 43 4.3. Amplitude vs Time visualization of a single DECT NR+ frame slot. . . . . . 44 4.4. Model of the power measurement scenario. . . . . . . . . . . . . . . . . . . . . 45 4.5. Power vs Frequency visualization of a single DECT NR+ frame slot. . . . . . 45 4.6. Power vs Time visualization of a single DECT NR+ frame slot. . . . . . . . . 45 4.7. Data rate (kbps) variation on MCS value change. . . . . . . . . . . . . . . . . 48 4.8. Diagram of the network scenario for the co-existence testing. . . . . . . . . . 51 4.9. Location of where the devices were located during the range testing. . . . . . 52 4.10. Test scenarios designed for the latency testing. . . . . . . . . . . . . . . . . . 55 4.11. Model of latency testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.12. Percentage of nodes in di!erent network tiers with di!erent scenario radiuses [NB22]. ....................................... 58 4.13. Bit and packet error error rates [Was+24]. . . . . . . . . . . . . . . . . . . . . 60 1. Amplitude vs Time visualization of two DECT NR+ frames with 2 consequent slotsand2slotgaps................................. 74 v 2. Amplitude vs Time visualization of two DECT NR+ frames with 8 consequent slotsand2slotgaps................................. 74 3. Amplitude vs Time visualization of a single DECT NR+ frame slot with 8 consequent slots and 2 slot gaps. . . . . . . . . . . . . . . . . . . . . . . . . . 75 4. Flow chart of the bidirectional ids.c code. .................... 76 5. Flow chart of the light control unicast code. . . . . . . . . . . . . . . . . . . . 77 6. Flow chart of the light control broadcast code. . . . . . . . . . . . . . . . . . 78 List of Tables 2.1. Comparison of 3GPP NR & DECT-2020 NR [DEC24]. . . . . . . . . . . . . . 8 2.2. Channel bandwidths in DECT-2020 NR. . . . . . . . . . . . . . . . . . . . . . 12 2.3. Modulation and coding schemes [21c]. . . . . . . . . . . . . . . . . . . . . . . 16 2.4. LPWAN Technology specification comparison. . . . . . . . . . . . . . . . . . . 25 3.1. NS3 modeling specifications for DECT NR+ technology. . . . . . . . . . . . . 29 3.2. Propagation model configuration for radio planning. . . . . . . . . . . . . . . 32 3.3. Transmitter configuration for radio planning simulation. . . . . . . . . . . . . 32 3.4. Receiver configuration for radio planning simulation. . . . . . . . . . . . . . . 33 3.5. Radio planning results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.1. nRF9161 Device Specifications [Nor24]. . . . . . . . . . . . . . . . . . . . . . 38 4.2. bidirectional ids.c inputparameters. ....................... 40 4.3. Power measurement results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.4. Data Rate Testing Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.5. Improvement of the data rate when the optimal consecutive subslots are used. 49 4.6. Summary of test parameters for co-existence testing. . . . . . . . . . . . . . . 50 4.7. Summary of obtained results for the di!erent co-existence cases that were tested......................................... 51 4.8. bidirectional ids.c configuration for range testing. . . . . . . . . . . . . . . . . 53 4.9. Latency Testing Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.10. Result of latency testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.11. Summary of the performance evaluation test results. . . . . . . . . . . . . . . 61 5.1. URLLCKPI. .................................... 63 5.2. mMTCKPI. .................................... 64 5.3. SmartlightingKPI. ................................ 66 5.4. Smart lighting configuration parameters. . . . . . . . . . . . . . . . . . . . . . 67 1. Data rate (kbit/s) testing comparison between di!erent MCS values with default values (2 consecutive slots) . . . . . . . . . . . . . . . . . . . . . . . . 70 2. Max obtained data rate (kbit/s) testing comparison between di!erent MCS values ........................................ 70 vii 1.3. Organization The rest of the document is organized as follows. The documents start with the background of the technology by explaining its history, main specifications and how it di!erentiates itself with technologies that also fall under the umbrella of Low-Power wide-area network (LPWAN) technology. The following chapter is a simulation and modeling of the technology, continuing with the evaluation of the technology where the networking, use of radio resources and performance has been extensively tested. The last chapter takes into account all the information gained from the previous chapters by showcasing three main use cases for the technology, and shows a practical implementation for a Smart Lighting solution using the available devices that support the technology. The document ends the overall conclusions of the work of this thesis, a list of figures, a list of tables and the bibliography of the resources used in the project. 3 2. Background In this chapter, the background of the DECT NR+ technology is presented by including a brief history of DECT NR+, the key features implemented by the technology, and an analysis of DECT NR+’s position within the wireless landscape. 2.1. Introduction This chapter provides an overview of the DECT NR+ technology, focusing on its history, key features, and specifications. The chapter begins with a brief history of DECT NR+ and its development, highlighting its evolution from the DECT standard to the current DECT NR+ technology. The chapter then presents the technical specifications and key features of DECT NR+, outlining the system architecture, networking capabilities, and other essential aspects of the technology. Finally, the chapter discusses the positioning of DECT NR+ within the wireless communication landscape, comparing it to other wireless technologies and highlighting its unique capabilities and use cases. This overview establishes a critical foundation for understanding the potential of this newly standardized technology, setting the stage for the detailed evaluation and practical implementation explored in subsequent chapters. 2.2. History of DECT NR+ As the development of new technological advances in the area of wireless communication in 1980s, the new ways to use the radio created a brand new ways to use the available radio resources. With the intend of creating a standard for cordless telephony, ETSI started developing the original DECT (Digital Enhanced Cordless Telecommunications) standard in 1988. Before DECT, the telecommunications landscape was dominated by analog cordless phone standards that were characterized by lower quality transmissions compared to DECT and lacked the advanced features and security protocols that DECT introduced. Additionally, the evolution of mobile communications technologies, such as GSM, began to emerge around this time, o!ering another form of wireless connectivity beyond traditional landline and cordless phones. The introduction of Wi-Fi in the late 1990s marked a pivotal moment in wireless communications, o!ering an alternative to wired connections for data transmission. However, DECT 4 initially focused on voice communications through cordless phones and later expanded into data applications, such as wireless LANs and wireless internet access services. Despite its advantages, including good range, high interference immunity, and support for fast roaming, DECT faced challenges in penetrating the wireless data market due to factors such as regulatory hurdles and competition from emerging technologies like Wi-Fi and cellular data services The technology that is being analyzed in this thesis, DECT NR+, is built upon the basis of the DECT technology, adding new features and capabilities to meet the requirements of the 5G standard. The development of 5G was driven by the need to support the growing demands of the internet of things (IoT), autonomous vehicles, and other advanced technologies that require high-speed, reliable, and secure connections. DECT NR + is promised to be one of the world’s first non-cellular 5G technology standards, which falls under the category of LPWAN (Low Power Wide Area Network) technologies. The technology allows any company or organization to build its own private 5G network, free of a traditional network operator. This approach can potentially lower both capital expenditures (CAPEX) and operational expenses (OPEX), as companies may avoid initial investments in partnering with telecom providers and reduce recurring subscription fees and service charges typically associated with cellular network usage. Additionally, by gaining control over network infrastructure and operations, businesses can optimize their spending on equipment and maintenance, potentially further reducing OPEX costs. This enables greater democratization of 5G networks, allowing users to implement their desired use cases with just the necessary devices, though they may still need to consider various factors including network setup, maintenance, and regulatory compliance. DECT NR+ was designed to be able to create a self-healing, decentralized, and autonomous mesh network, allowing easy device addition and eliminating single points of failure. Each node can function as an access point with direct internet connection, adapting roles based on network needs. This mesh technology o!ers flexibility and scalability across industries, utilizing cellular techniques for robustness. Operating on the 1.9 GHz band reduces deployment costs by eliminating frequency planning and certification requirements. The ETSI DECT forum [DEC] started working in the standard in early 2018 and was completed in July 2020. The DECT forum built DECT NR+ upon the basis of the DECT2020 NR ETSI standard, which is based on the IMT-2020 technology recommendation [Int23] as in the ITU-R [Int24] recognized by WP5D as a term to describe the global vision for 5G. 2.2.1. 5G The DECT NR+ technology is designed to meet the requirements of the Ultra Reliable Low Latency Communications (URLLC) and massive Machine Type Communications (mMTC) use cases of IMT-2020. These two requirements are part of the three main use cases of 5G 5 shown in the figure 2.1, along with Enhanced Mobile Broadband (eMBB) that focuses in higher peak data rates. Figure 2.1.: Services that can be implemented on technological basis of 5G generation communication networks. 5G URLLC URLLC stands for Ultra Reliable Low Latency Communications. As its name implies, it focuses on ensuring extremely high reliability and very low latency for critical applications. Such applications might include autonomous vehicles, industrial automation, and remote surgery, where even a slight delay or failure could lead to catastrophic outcomes. Here are the key requirements for URLLC in 5G: •Reliability: URLLC aims to provide a reliability level of 99.999% for mission-critical applications. This means that the system should be designed to minimize errors and failures to an extremely low rate. •Latency: The target latency for URLLC is less than 1 millisecond (ms). This is significantly lower than the latency targets set for general-purpose 5G services, reflecting the need for near-instantaneous communication in critical applications. •Availability: URLLC must maintain service availability under all conditions, including extreme weather, high tra”c loads, and network congestion. This requires robust network design and redundancy measures. •Scalability: As the number of connected devices increases, the network must still be able to guarantee URLLC requirements without degradation in performance. 6 This requirements are more extensively explained later in the 5.2 section of this document. 5G mMTC mMTC (Massive Machine-Type Communications) is mainly designed to support self-configured and infrastructure-less wireless sensor networks. mMTC enables connections for vast numbers of IoT devices and it supports applications like smart cities, where it monitors utilities, waste management, and air quality to create more e”cient urban environments. These use cases leverage mMTC’s ability to connect up to one million devices per square kilometer, enabling widespread IoT deployments across industries. The key requirements for mMTC in 5G are as follows: •Device Density: Networks must be capable of supporting a very high density of connected devices, at least one million devices per square kilometer with the minimum message density of one packet per two hours. •Low Power Consumption: Devices connected via mMTC should consume minimal power, extending battery life and making deployment easier, especially in environments where replacing batteries frequently is impractical. •E!cient Spectrum Usage: Given the sheer volume of devices, e”cient use of spectrum is crucial to avoid congestion and ensure fair access to resources. •Cost-E”ectiveness: The infrastructure and devices supporting mMTC should be cost-e!ective to deploy and operate, considering the scale at which these networks will be rolled out. This requirements are more extensively explained later in the 5.3 section of this document. Overall, the technology promises to fulfill the requirements of this two brand new main use cases. 3GPP NR Apart from DECT NR+, 3GPP NR [3GP22] is also mentioned as the main technology for mobile broadband communication inside 5G. 3GPP NR is part of the ongoing evolution of mobile broadband communication standards, building upon previous generations (2G, 3G, 4G/LTE) to meet the increasing demands of modern applications. As it can be seen on the table 2.1, 3GPP NR is geared towards mobile broadband and supports a wide range of mobile devices and applications, including smartphones, laptops, and IoT devices. In contrast, DECT NR focuses on providing highly capable and scalable private networking. 3GPP NR operates across a broad spectrum, including both sub-6 GHz and mmWave bands, to deliver high data rates and low latency. In contrast, DECT NR typically uses 7 licensed spectrum in the 1.8 GHz to 1.9 GHz band. 3GPP NR is designed to handle massive connectivity and high data rates, supporting thousands of users and devices simultaneously, thanks to its backhaul architecture. Meanwhile DECT NR, while capable of supporting multiple devices, is generally focused on smaller-scale deployments that don’t require that much planing. In summary, as it can be seen in the 2.1. figure, while both 3GPP NR and DECT NR are related to the evolution of wireless communication technologies, they address di!erent needs and environments. While 3GPP NR is a global standard for mobile broadband, catering to the demands of a wide range of mobile devices and applications, DECT NR focuses in bringing infrastructure-less network topologies to the end user for use cases that focus on low latency and high device densities. In this thesis, the scalability and performance of DECT NR+ are evaluated to determine its suitability for various use cases and applications. Table 2.1.: Comparison of 3GPP NR & DECT-2020 NR [DEC24]. Parameter 3GPP NR DECT-2020 NR Spectrum Spectrum Auctioned to MNO; site Licensed (Campus) License exempt for 1,9 GHz Topology Cellular P2P1, P2M2, Mesh and Cellular3 Infrastructure Base station (BS) and User Equipment (UE) managed by MNO (Mobile Network Operator) Local Self-organizing RDs with context based roles Use cases eMBB, URLLC, mMTC URLLC, mMTC The next section will present the technical specifications and key features implemented in the DECT NR+ technology that have been designed and implemented to meet this requirements. In this thesis, this new key features are analyzed to check if the technology is capable of meeting the requirements of the URLLC and mMTC use cases. 2.3. Specifications In this section the technical specifications and key features implemented in the DECT NR+ technology are presented. The information is mainly based on the ETSI technical specifications [21b; 21c; 23] and the DECT NR+ whitepaper [DEC24]. This information is crucial for understanding the technology and its capabilities, as well as for understanding how the technical advancements promised by the technology are accomplished. 1P2P: Point-to-Point 2P2M: Point-to-Multipoint 3DECT NR+ is mainly designed to support self-configured and infrastructure-less wireless networks that work for P2P, P2M and Mesh topologies, but it also supports cell topologies, even though it’s not it’s main purpose. 8 2.3.1. System Architecture The architecture of the DECT NR+ system can be defined in di!erent layers that will be described in this chapter. The architecture follows the figure 2.2, where each layer implements an specific sets of functionalities that adds to the overall functionality of the system. It starts with the Physical (PHY) layer, responsible for the transmission and reception of radio signals. Above it, the Medium Access Control (MAC) layer manages access to the communication medium, ensuring e”cient data transmission. The Data Link Control (DLC) layer handles routing and link management between devices. Moving up, the Convergence (CVG) layer provides essential services such as transmission, security, and endpoint multiplexing, facilitating secure and reliable communication. At the top, the IPv6 and Application layers manage user applications and IP-based communication, completing the data flow across the network. Figure 2.2.: Illustration of overall protocol stack architecture of DECT-2020 [21b]. 2.3.2. Networking As of networking, DECT NR+ o!ers di!erent types of topologies that can be used to build local area wireless access networks, that don’t relay on a cellular network. Devices in the network are known as Radio Device (RD) that have radio transmission and reception capabilities, which can operate in the following distinct operational modes: •Fixed Termination (FT): RD initiates coordinates local radio resources, provides information how other RDs may connect and communicate with it. It also provides connection as a sink to other external services and networks. •Portable Termination (PT): RD selects another RD, which is in FT mode, for association. It acts as a user equipment or end node in the network. The following di!erent network topologies are supported by DECT NR+, each optimized for di!erent use cases: 9 Wireless Point-to-Point and Point-to-Multipoint Links DECT NR+, as its acronym clearly implies (Digital Enhanced Cordless Telecommunications), can be used as a very reliable Point-to-Point and Point-to-Multipoint Wireless Links provisioning as a cable replacement solution by a wireless link established between two radio devices requiring communicating with each other. This type of network topology is also known as a star topology, when several end nodes are connected to the main node, and it allows support for URLLC use cases and is also used in technologies such as LoRA, Sigfox and NB-Iot, as shown in a later section of this document. Compared to wireline systems, wireless comes with the benefit that point to multipoint communication is an inherent feature of radio propagation, so that the support of broadcast and multicast messages from one point to multiple points is just a matter of protocol. The radio connection between two or more radio devices is enabled by one RD selecting to operate in FT mode (RDFT) and initiate radio resource coordination and beacon transmissions. Other RD(s) perform association procedure in PT mode (RDPT) and with the RDFT. Mesh networking The mesh networking capability of DECT NR+ enables application-driven network topologies and deployments in e.g., mMTC use scenarios, such that the link budget of classical cellular base-station user equipment constellations is no longer a limiting factor. Mesh topology can support high device densities, and the autonomous routing provides the ability to adapt dynamically to mobile users and interference. This networking functionality is one of the main key features of DECT NR+ that makes it unique compared to other LPWAN technologies. As defined in the standard [21b], the mesh system operation is based on a clustered tree topology where each RD decides the next hop individually based on available routes towards the RD providing the connection to the external resources. Each radio device has knowledge of the next uplink and downlink hop in the clustered tree and RDFT, or RDFT,PT mode in each cluster controls radio resources (frequency bands, HARQ, MCS...) and transmissions independently for each radio link. The network is initiated by an RDFT that is connected to one or multiple backend resources, which selects the operating frequency/ies and initiates a beacon transmission indicating that it has a route to the external world. Thanks to this, the RDs in the network detect the beacon and evaluate the connection based on the information included in the received beacon and decide to associate with the RD providing the best connection to the sink. The process continues to the next hops and so on, as illustrated in the figure 2.3. Radio devices can change roles based on network needs, e.g. an RD may change from PT to FT mode, or vice versa, based on the network needs. 10 The routing functionality in mesh networks adds complexity to the network and the protocols used, but it also provides redundancy and fault tolerance. If one node cannot reach the destination, it can send the data to another node that can. This makes mesh networks more reliable than network topologies that the rest of LPWAN technologies provide. The routing is based on a cost value, without the need to maintain routing tables in each device. The consequences of this added extra level of complexity needs to be studied in terms of reliability, scalability and power consumption, before the deployment of the corresponding application that uses this networking solution. Local Area Wireless Access Networks in Cellular Network topology Even though DECT NR+ is a non-cellular technology, it can still be used to build local area wireless access networks following a cellular network topology. This allows the deployment of a large number of radio devices in a small area, which can be used to support mMTC use cases. A single-cell network topology involves an RDFT as a base station, which is a component of the fixed network infrastructure, and other RDPT as user equipment in the network. RDFT coordinates the radio resources and provides information on how other RDs may connect and communicate with it. RDPT selects the RDFT for association and communication. Figure 2.3.: Formation of the clustered tree mesh network topology [21b]. 2.3.3. Physical Layer Looking at the ETSI technical Specification of the physical layer of DECT NR + [23], the physical layer employs multiple numerologies, with di!erent subcarrier spacings factors, known as µ, and corresponding Cyclic Prefix lengths and FFT sizes, allowing operation with di!erent channel bandwidths, and optimize operations in di!erent frequency bands and 11 propagation environments. In addition, the Fourier transform scaling factor, also known as ω, can be set to allow di!erent transmission bandwidths for each configuration of the subcarrier spacing. This results in the support of nominal RF bandwidth from 1,728 MHz up to 221,184 MHz, where the nominal and transmission channel bandwidths are defined in the table 2.2. The capability to operate at high bandwidth values enables higher data throughput in transmission, compared to other Low-Power Wide-Area Network (LPWAN) technologies. Table 2.2.: Channel bandwidths in DECT-2020 NR. Channel Type Nominal channel bandwidth (MHz) Transmission channel bandwidth (MHz) Operating channel bandwidth I 1,728 MHz 1,539 MHz Operating channel bandwidth II 3,456 MHz 3,051 MHz Operating channel bandwidth III 6,912 MHz 6,075 MHz Radio characteristics ETSI defines 17 operating bands from 450 MHz up to 5 875 Mhz. The wide range of operating bands in DECT NR+ technology caters to a multitude of use cases, enhancing its versatility. However, this diversity also demands meticulous analysis to ensure the correct configuration of DECT NR+ for the appropriate frequency band, crucial for optimizing performance. The range of available channels can be seen more clearly in the figure 2.4 taken from the ETSI standard [21c]. During the work of this thesis, the band 1 channel 1677 (1899,069 MHz) has been used, as it’s the main one marketed by the DECT forum. The minimum channel spacing is 1,728 MHZ between adjacent channels centre to centre frequencies. Moreover, up to 8x8 open loop streams of MIMO and beamforming can be used during the antenna processing for enhancing the capacity and reliability of wireless communications, especially in challenging propagation environments such as urban areas with dense buildings or in high-speed vehicular scenarios. Power levels For transmitter operation, maximum output power classes of 23dBm, 19dBm, and 10dBm are specified, with a ±2dB power tolerance. This flexibility allows for adaptation to various application requirements, including battery-powered scenarios. Additionally, the transmitter output power can be adjusted down to -40dBm, facilitating high equipment density use cases. 12 approach makes HARQ particularly e!ective in varying signal conditions. The influence of this error control mechanism on latency and data rates during transmission needs to be analyzed within the DECT NR+ technology framework to ensure reliability for use cases requiring low latency and high data rates. 2.3.5. Data Link Control and Convergence Layer The Data Link Control (DLC) and Convergence layers play a crucial role in network communication, o!ering flexibility in system architecture. The DLC layer is responsible for essential functions at each radio link, including segmentation and packet routing, which are vital for managing data transmission e”ciently. The architecture of the DLC involves a single routing service entity in each Radio Device (RD), with distinct DLC entity sets for di!erent operational modes and communication scenarios. These entities handle various service modes based on Quality of Service (QoS) and application data format requirements, ensuring data is transmitted and received according to the specific needs of the network and its applications. The DLC layer supports advanced features like transparent mode for straightforward data transmission and segmentation mode for dividing data into smaller segments for e”cient transmission. Additionally, the DLC layer facilitates packet routing in various directions (backend to RD, RD to backend, and between RDs) using unicast, multicast, or broadcast addresses, enhancing the flexibility and adaptability of the network communication process. 2.3.6. Co-existence DECT NR+ was designed to be backwards compatible with previous DECT versions by supporting the same frequency bands (1880 MHz to 1900 MHz), frame structure, and timing. This ensures that DECT NR+ devices can operate alongside older DECT technologies without interference, allowing for a smooth transition to the new standard. Additionally, DECT NR+ incorporates new features like the previously presented Hybrid HARQ, CPOFDM, and LBT for random access resources. These features enhance the performance and e”ciency of DECT NR+ networks, making them more robust and reliable in challenging environments. 2.4. Comparisons 2.4.1. Introduction In this section of the document, a comparative analysis of DECT NR+ technology is conducted against other similar wireless communication technologies. The focus lies on examining the features, specifications, and use cases that di!erentiate each technology, more 19 specifically in the european market. The reason behind this comparison is to grasp a broader understanding of the environment in which DECT NR+ technology operates. By contrasting DECT NR+ with alternative technologies, it becomes possible to identify its place within the wider ecosystem of wireless communication solutions. This comparison not only stresses the competitive dynamics but also highlights the distinctive characteristics that the DECT NR+ technology o!ers. Furthermore, tracing the trajectory of these technologies over time reveals significant trends in technological progression. These trends may suggest potential pathways for the evolution of DECT NR+, o!ering insights into future developments or uncovering avenues for innovation and refinement, or even highlight the innovative features that DECT NR+ already implements. 2.4.2. LTE-M Starting with LTE-M [GSM19], this technology is a low-power wide-area network (LPWAN) technology that operates on licensed spectrum, promising extended coverage and improved battery life for IoT devices. LTE-M is designed to support massive machine-type communication (mMTC) applications, just like in the case for DECT NR+, making it suitable for a wide range of IoT use cases. However, LTE-M has certain limitations and characteristics that di!erentiate it from DECT NR+ technology. As opposed to LTE-M, DECT NR+ operates in the license-exempt 1.9 GHz spectrum. This allows for free use without the need for purchasing licenses, significantly reducing operational costs compared to LTE-M, which requires licensed spectrum and thus incurs licensing fees. This aspect makes DECT NR+ more cost-e!ective for IoT deployments, especially in scenarios where licensing fees are a concern. Moreover, LTE-M needs a carrierprovided backbone network, o!ering less flexibility in terms of network architecture and deployment compared to DECT NR+, which allows for private mesh networks without the need for SIM cards or costly base stations. However, the availability of being connected to a carrier network backbone allows the devices in the LTE-M network to access external services and the internet, simpler than in the DECT NR+ network. It is true that LTE-M o!ers a wider device range coverage at around 11km, but at the cost of a lower device density and data rate. DECT NR+ is designed for shorter-range communications, typically up to 3 kilometers, making it suitable for localized IoT networks such as those found in smart cities, factories, or large buildings. This characteristic is particularly advantageous for IoT applications requiring the connection of numerous devices within a limited area, where DECT NR+ can provide better performance in congested environments due to its ability to support high-density deployments e”ciently. As previously said, while both technologies serve mMTC applications, DECT NR+ is specifically tailored for mMTC and ultra-reliable low-latency communication (URLLC). 20 LTE-M, on the other hand, serves a broader general-purpose audience, including M2M applications that may not require the same level of reliability or low latency as DECT NR+. 2.4.3. NB-IoT As LTE-M, NB-IoT (Narrowband Internet of Things) [GSMb] is a cellular technology designed specifically for low-power wide-area networks (LPWANs). However, as LTE-M is best suited to applications requiring relatively high uplink and downlink speeds in the context of IoT, NB-IoT focuses on optimizing devices that require minimal power consumption and transmit small amounts of data infrequently, by lowering the bandwidth (180 KHz) and having higher latency (1.5-10sec). DECT NR+, on the other hand, is designed for high-density IoT networks and can support both high data rates and low power consumption depending on the application. A research by Roman Kovalchukov called “DECT-2020 New Radio: The Next Step toward 5G Massive Machine-Type Communications”(2022) [Kov+22] indicated that DECT 2020 NR (the basis for DECT NR+) is significantly more power-e”cient than NB-IoT, showing up to 24 times more e”ciency when applied to Bluetooth silicon and a 2.4 times improvement in power e”ciency over NB-IoT devices when flashed onto cellular chips. 2.4.4. Bluetooth 5.3 Low Energy Bluetooth Low Energy (BLE) [RFP24] is designed for short-range communication between devices. It is widely used in wearables, smart home devices and some IoT applications,due to its low power consumption and ease of use. Bluetooth 5.3 is the latest version of the BLE standard, o!ering improved range, speed, and security features compared to previous versions. While BLE is suitable for many IoT applications, it has certain limitations that di!erentiate it from DECT NR+. BLE operates in the 2.4 GHz ISM band, which is a crowded frequency band that can lead to interference and reduced performance in congested environments. BLE has a range of around 100 meters, which is su”cient for many IoT applications but may not be suitable for large-scale deployments or outdoor environments. Another key di!erence between DECT NR+ and BLE is the data rate. DECT NR+ o!ers a higher data rate of 3.4 Mbps, making it suitable for applications requiring high-speed data transfer, such as video streaming or real-time monitoring. BLE, on the other hand, has a lower data rate of 250 kbps, which may be su”cient for many IoT applications but may not meet the requirements of high-bandwidth applications. In terms of power consumption, both DECT NR+ and BLE are designed to be low-power technologies, making them suitable for battery-operated devices. BLE also allows mesh networking capabilities, but not by default, only when additional protocols and modules are incorporated on top of the LE base. 21 2.4.5. IEEE 802.15.4 IEEE 802.15.4 [IEE] is a technical standard that defines the operation of low-rate wireless personal area networks (LR-WPANs) in which technologies such as Zigbee, Thread, and 6LoWPAN are based on. It is widely used in IoT applications, industrial automation, and smart home devices due to its low power consumption and low data rate. IEEE 802.15.4, like the previously mentioned technologies, operates in the 2.4 GHz ISM band and o!ers a communication range of up to 10 meters with line of sight at a transfer rate of 250 kbps. While IEEE 802.15.4 is suitable for many IoT applications, it has certain limitations that di!erentiate it from DECT NR+. IEEE 802.15.4 is designed for short-range communication and may not be suitable for applications requiring extended coverage or high device density. DECT NR+, on the other hand, o!ers a longer range of up to several kilometers and can support high-density deployments with minimal power consumption. 2.4.6. LoRaWAN LoRaWAN (Long Range Wide Area Network) [GSMa] is a private wireless communication technology that is widely used in IoT applications, smart cities, and industrial automation. It operates in the unlicensed ISM bands (868 MHz in Europe and 915 MHz in the US) and o!ers a long communication range of up to 10 kilometers in rural areas and 1 kilometer in urban areas. LoRa is designed for low-power, wide-area networks (LPWANs) and o!ers a low data rate of up to 50 kbps. This lower frequencies help the signal to travel further, but at the cost of a lower data rate. It’s a private technology for private networks, therefore it’s not suitable for public networks. LoRa is a good technology for long-range communication, but it may not be suitable for applications requiring high data rates or high device density. DECT NR+ o!ers a higher data rate and can support high-density deployments with minimal power consumption, making it suitable for a wide range of IoT applications. It can be said that NR + makes an open and standardized alternative to this proprietary technology, even though its di!erences to LoRaWAN in networking and data rate capabilities. 2.4.7. Conclusions In conclusion, the comparative analysis of DECT NR+ with other wireless communication technologies reveals that DECT NR+ o!ers unique features and capabilities that set it apart from existing solutions. Specifically, DECT NR+ is optimized for high-density IoT networks, supporting both high data rates of up to 3.4 Mbps and low power consumption. This combination makes it particularly suitable for a wide range of IoT applications, including smart city infrastructure, industrial automation, and large-scale building management systems. Operating in the license-exempt 1.9 GHz spectrum, DECT NR+ eliminates the need for 22 costly licensing fees associated with other technologies. This aspect significantly reduces operational costs, making it an attractive option for organizations seeking to deploy IoT solutions without substantial upfront investments. The technology’s extended range of up to several kilometers further enhances its appeal for localized IoT networks. This capability allows for seamless coverage across large industrial facilities, urban areas, or sprawling campus environments, addressing connectivity challenges faced by traditional short-range IoT solutions. As demonstrated in Table 2.4, DECT NR+ o!ers unprecedented possibilities in the IoT field. Its unique combination of high data rates and extensive range positions it as a leader among comparable wireless communication technologies. Figure 2.9 illustrates this advantage visually, showcasing DECT NR+ as the only candidate o!ering both high range and data rates simultaneously. Moreover, DECT NR+ facilitates more complex network topologies and enables true duplex communication between devices. Unlike many existing IoT technologies that rely on simple reporting nodes, DECT NR+ supports advanced mesh networking capabilities. This feature allows for dynamic network reconfiguration and enhanced reliability, crucial factors in mission-critical IoT applications. In light of these findings, it is concluded that DECT NR+ represents a significant advancement in wireless communication technology for IoT applications. Its unique blend of performance, flexibility, and cost-e!ectiveness makes it an attractive solution for organizations seeking to deploy robust, scalable IoT networks across various industries. As the IoT landscape continues to evolve, DECT NR+ is poised to play a crucial role in enabling next-generation smart infrastructure and industrial automation systems. 23 Figure 2.9.: Comparison of technologies based on their max data rates and range. 24 Table 2.4.: LPWAN Technology specification comparison. Specifications DECT NR+ LTE-M NB-IoT BLE 5.3 IEEE 802.15.4 LoRa WAN Release Release 2 June 2023 3GPP Release 13 June 2016 3GPP Release 13 June 2016 July 2021 Latest July 2020 January 2015 Range up to several km 5km Urban: 1km Rural: 10km c.a. 100 m 10 →75 m Urban: 2-5km Rural: 15km Frequency Bands B1 (1.9 GHz) B20 (833-862 MHz) B3 (1800), B8 (900) and B20 (800) 2.4 GHz ISM 868/915 MHz & 2.4 GHz 863-870 MHz Max EIRP Power 23 dBm 30 dBm 20/23 dBm 20 dBm 20 dBm 14 dBm outdoor RX sensitivity -99,7 dBm [Ant+21] -126 dBm -141 dBm -96,7 dBm [22] -96,7 dBm [22] -128 dBm [Rav24] Bandwidth 1,728 MHz 1.4-5 MHz 180 kHz 5 MHz 5 MHz (2 MHz) max 500 kHz DL peak rate 3.4 Mbps 1 Mbps 26 Kbps 250 kbps 250 kbps 50 kbps UP peak rate 3.4 Mbps 1 Mbps 66 Kbps 250 kbps 250 kbps 50 kbps Latency 1 ms 10-15 ms 1.5-10 s 40 ms →50ms Seconds Modulation CP-OFDM OFDMA OFDMA GFSK O-QPSK / GFSK FSS / CSS Duplex mode Full / Half Full / Half Half Half Half Half Networking PtP / Star /Mesh Star Star PtP / Star /Mesh PtP / Star /Mesh Star Devices/km 1001million - - Thousands Thousands Thousands 25 2.5. Summary This chapter provides an overview of the DECT NR+ technology, focusing on its history, system architecture, and di!erentiation from other technologies in the market. Its versatility in supporting various network topologies (point-to-point, point-to-multipoint, cellular, and mesh networks) and the ability to create self-deployed networks make it an attractive solution for a wide range of applications. The physical layer utilizes multiple modulation schemes and coding rates to optimize data transmission across di!erent frequency bands and propagation environments. The MAC layer ensures e”cient access control and secure communication. The DLC and Convergence layers provide essential functions for packet routing and data segmentation, supporting various service modes and QoS requirements. The subsequent chapters will delve into the modeling and implementation of DECT NR+ technology in real-world scenarios using the first available devices implementing this technology. This exploration aims to assess its performance and capabilities in practical settings, as there is currently limited public research on this topic, due to DECT NR+ being a newly emerging technology. In this exploration, the correct functionalities of the methods that the technology implements for achieving the requirements for URLLC and mMTC, e.g., HARQ and LBT, are analyzed. Such analysis is vital before the technology is even considered to be implemented in actual use cases. 26 3. Simulation and Modeling In this chapter the simulation and modeling of the DECT NR+ technology will be discussed. 3.1. Introduction Now that the technology has been properly introduced and compared to the rest of technologies in the LP-WAN landscape, the next step is to simulate and model the technology to better understand its capabilities and how it can be used in di!erent scenarios. The simulation and modeling of the technology has been done in two di!erent ways, one using the NS3 software for the networking part of the technology and the other using Matlab for the radio planning part of the technology. Analyzing DECT NR+ technology requires a deep understanding the use of its radio capabilities (RF) and networking capabilities. For networking aspects, simulation focuses on the protocol stack, including physical layer characteristics, data link protocols, and network layer functionalities. This involves modeling the modulation schemes, error correction codes, and packet structures used by DECT NR+. Simulation tools can help assess the system’s performance under various tra”c loads, interference levels, and mobility scenarios, providing insights into throughput, latency, and reliability. By combining RF and networking simulations, developers can gain a comprehensive understanding of how DECT NR+ technology will perform in real-world applications. This approach allows for optimization of both hardware components, such as antennas and transceivers, and software elements, including communication protocols and algorithms, before moving to physical testing. Such thorough simulation e!orts ensure that the final product meets the desired performance criteria, reduces development costs, and accelerates time-to-market. 3.2. Network simulation - NS3 The NS3 simulation software [] has been utilized for simulating DECT NR+ technology. This community-driven, open-source software is a discrete-event network simulator widely employed for research and educational purposes. NS3 o!ers a modular architecture, enabling users to create custom network models, protocols, and applications, making it adaptable for 27 simulating a broad spectrum of wireless technologies. Users primarily interact with NS-3 through command-line interfaces and develop simulations using C++ and/or Python. As of date of writing this document, there is no DECT NR+ module available in NS3. To address this gap, several researchers who have previously worked on simulating DECT NR+ technology were contacted for guidance on how to proceed with the simulation. Roman Kovalchukov, author of the research paper “DECT-2020 New Radio: The Next Step Towards 5G Massive Machine-Type Communications” [Kov+22], suggested utilizing the IEEE 802.15.4 model [ns-24a] as a foundation for modeling DECT NR+ technology. In contrast, Timo Nihtilae, author of the “Energy Consumption of DECT-2020 NR Mesh Networks” research paper [NB22], recommended employing the 802.11s mesh model [ns-24b] due to similarities between the MAC layers of DECT NR+ and 802.11s. Considering these recommendations, both models were analyzed and compared to determine which one aligns better with the technology under investigation. While the IEEE 802.15.4 model serves as an excellent starting point due to its relevance to low-power, lowrate wireless personal area networks (LR-WPANs) commonly used in IoT applications, the 802.11s mesh model was ultimately chosen. This decision was made because the 802.11s model facilitates more complex mesh configurations, which is crucial for the intended simulations. Additionally, it supports frequency spreading, enabling the simulation of DECT NR+ technology’s MAC layer Random Access Channel (RACH). Design of the simulation For the testing the 802.11s mesh model has been used for the simulating the mesh capabilities of the DECT NR+ technology in a URLLC use case where one network that consists in one RDFT and the e!ect of amount of RDPT for one RDFT has been simulated and analyzed. The simulated model follows the model shown in the figure 3.1. Due to the reason that creating a brand new NS3 module for DECT NR+ from teh start goes beyond the timing and interest of this thesis, instead of creating a brand new model for the DECT NR+ technology, the 802.11s mesh model has been used as a starting point to simulate the mesh capabilities of the DECT NR+ technology. To simulate the technology the parameters defined in the table 3.1 have been defined. In the simulation and UDP echo server has been installed in the device 0 that simulates aRDFT. As the UDP echo client, a node in the opposite corner of the network has been selected to which the rest of the nodes on the network send the data to. As explained in the NS3 802.11a mesh model, were this simulation is based on, the node spacing e!ects in the following way: •Short distances (<15 meters): Direct communication possible. •Intermediate distances (15 ↑30 meters): Two-hop diagonal routes used. 28 tations of existing models, such as IEEE 802.11s, due to the absence of a dedicated DECT NR+ module. While this approach has provided meaningful preliminary results, further work could involve developing and testing a dedicated DECT NR+ module within NS3 to provide a more accurate representation of the technology’s performance. 35 4. Evaluation of DECT NR+ technology Chapter dedicated to the testing followed for the characterization of the DECT NR+ technology via specification, functionality and RF testing. 4.1. Introduction The DECT NR+ technology, though relatively new, presents significant opportunities for wireless communication systems. As of the development of this thesis, there is a notable absence of empirical studies on the capabilities of DECT NR+ technology in actual devices. This gap in knowledge stems from the technology’s recent introduction, with most research based on simulations and theoretical models rather than practical implementations. This chapter aims to address this knowledge gap by providing a comprehensive evaluation of DECT NR+ technology. The focus is on analyzing the technology’s promises against its actual capabilities, utilizing the first available devices implementing this technology. The objective is to assess whether these initial implementations meet the expected standards and potential of DECT NR+. To achieve this objective, an extensive testing of key specifications of the technology was conducted. This evaluation was crucial for understanding the technology’s capabilities and limitations, which are essential for determining its suitability for various use cases and applications. The research contributes significantly to the development of DECT NR+ technology by providing empirical evidence of its real-world performance. The evaluation process utilized the Nordic nRF9161 System-in-Package (SiP), which incorporates DECT NR+ capabilities along with LTE-M/NB-IoT support. The assessment encompassed netowrking functionalities, RF capabilities and device specifications (data rate, delay, range...). This comprehensive evaluation allowed insights into the practical implications of DECT NR+ technology in real-world scenarios. This chapter serves as a foundation for future research and development in the field of DECT NR+, providing valuable insights into its current state and potential applications. By bridging the gap between theoretical expectations and practical realities, the study contributes to the advancement of wireless communication technologies and their integration into IoT ecosystems. 36 4.2. Equipment 4.2.1. nr9161 Development Kit For the analysis of the DECT NR+ technology, Nordic’s nr9161 development kit [Nora] has been used. As noted previously, this kit is one of the first devices that implements an early version of a DECT NR+ modem that finally allows developers to start creating the first batch of applications that utilizes this technology. Device Specifications The specifications of the device can be seen in the table 4.1. This devices is one the first device available for valuation and development of the DECT NR+ technology, and therefore it has the following limitations in regards of the capabilities that the technology has been designed to o!er. •DECT NR+ supported bands: The device is capable of transmitting only in the 1, 2 and 9 DECT NR+ bands, which corresponds to the license-free bands where the technology can work on. The standard defines a broader variety of bands to chose from [2.4], from lower frequencies for higher range and lower data rates, and higher frequencies, up to 6 GHz for higher data rates for devices closer to each other. •Bandwidth (MHz): The device is capable of transmitting with a bandwidth of 1.728 MHz, which is lower than the 6.912 MHz that the technology is capable of transmitting [2.2]. This a!ects the data rate that the device can o!er. •Functionality: The modem running in the device only implements the PHY layer of the technology, therefore, the main characteristic of the technology can’t be tested, i.e. the mesh network capabilities. •Power Output: The device is capable of transmitting with a maximum power of 19 dBm, which is lower than the 23 dBm promised by the standard. This a!ects the range and the reliability of the technology. •Antenna limitations: As only one antenna output is supported at a time, the device can’t be used in MIMO configurations, which a!ects the reliability. Moreover, no multiple streams can be transmitted at the same time, which a!ects the data rates that the device can o!er. •MCS values: The device is capable of transmitting up to the value of 4 for MCS, which is lower than the 11 that the technology is capable of transmitting [2.3]. This a!ects the max data rates that the device can o!er. 37 Even though it has limitations, in its technical specification it is promised to implement the correct slot mechanisms, the correct frequency and the correct power values that are needed for the DECT NR+ technology. Also HARQ is implemented in the modem and the LBT for random access. The evaluation of the technology should be continued as more capable modems are available in the market. Table 4.1.: nRF9161 Device Specifications [Nor24]. Parameter Value DECT NR + supported bands 1, 2, 9 [2.4] Transmission Bandwidth (MHz) 1.728 [2.2] Occupied Bandwidth (MHz) 1.539 [2.2] Antenna impedance , single-ended (#)50 RX: Sensitivity 1, modulation MCS1 (dBm) -103 TX: Maximum output power (dBm) 19 TX: Minimum output power (dBm) -40 Antenna Ethertronics P822601 [6] LEDs 4 Buttons 4 Used DECT perf commands The perf tool o!ered by the DECT NR+ modem has been very resourceful throughout the testing section of this document as it allows continuous transmission between two devices and reports data rates along with more valuable information regarding the transmission, including the number of bits transmitted and errors that occurred during transmission. The perf tool has been utilized with the following commands: •Server:dectperf-s-t-1-h –-s: Server role. –-t: Duration time. Is set to -1 for continuous server. –-h: HARQ activated. This parameter is deactivated when the testing is done without the HARQ. •Client: dect perf -c -t 10 –c tx pwr -8 –c tx mcs 4 -h –-c: Client role. –-t: Duration time. Is set to 10 seconds, as the realized test last for 10 seconds. 38 – –c tx pwr:TXpowerindBm.Issetto-8dBm. – –c tx mcs: MCS value. This value has been through the test to test the data rate each MCS value can o!er. –-h: HARQ activated. This parameter is deactivated when the testing is done without the HARQ. The data transmitted was a temperature value that was being sent from one device to the other. 4.3. Network evaluation DECT NR+ has been designed to allow di!erent types of network architectures, such as point-to-point, point-to-multipoint, and mesh networks, as explained previously in the section 2.3.2. The following sections will describe how the di!erent types of networking are be implemented in the first devices that implement the technology. Point-to-point communication For point-to-point communication, the modem provides the correct functionality that allows this networking architecture. For this purpose, bidirectional ids.c has been developed, which is based on the hello world.c code from the version 1.0 of the DECT NR+ modem provided by Nordic. This code has been used to test the bidirectional communication between two RDs, where both devices can transmit and receive messages through the same channel. This code is available in the Github repository of the project [Jau], with all the information related to how to executed in a local machine shown in the main README.md file of the project. The main loop of the program facilitates continuous communication within the DECT NR+ network by transmitting broadcast messages and managing device connections. After broadcasting, the program checks if any devices are present in the network. If devices are detected, it sends unicast messages to each, while removing any inactive devices from the list. The program then listens for incoming messages and updates the devices array with any newly discovered devices. This loop ensures that the devices in the network are consistently monitored and updated, allowing for stable and dynamic point-to-point communication between registered devices. The operation of the code is also presented in a simple flow chart in the figure 4. This code has been very useful in the testing of the range of the DECT NR+ technology, as it allows the reporting of when the devices loose the connection ot each other and also the RSSI and RSSI 2 levels of the connection. The input parameters shown in the table 4.2 can be configured in the code. 39 Table 4.2.: bidirectional ids.c input parameters. Parameter Description CONFIG CARRIER Carrier frequency CONFIG NETWORK ID Network ID CONFIG TX POWER Transmission power CONFIG MCS Modulation and coding scheme CONFIG RX PERIOD S Receive period CONFIG TX TRANSMISSIONS Number of transmissions Point-to-multipoint communication The correct functionality of the point-to-multipoint communication has been tested using a simple code provided by Nordic in pre-alpha version of the modem that broadcasts a counter and turns on the LEDs of the device while transmitting. This code has been used as a base for the development of the other codes used in the thesis, as explained in the previous subsection. This simple code has been modified with the name of broadcast.c to allow the reporting of the RSSI and RSSI 2 levels of the connection, the number of packets sent and received, the number of errors, and the packets that have been lost. The input parameters are the same as for bidirectional id.c and are shown in the table 4.2. This code is also available in the Github repository of the project [Jau]. As for the functionality of the code, the device first listens on hard-coded channel for 10sec, if no transmission detected, starts sending for-ever. Another device can start, listens and stays in listen mode, simple statistics are provided at end, when button is pressed. Reset board to start again. The LED and button of the code have been useful for the development of the other codes, as the LEDs can be used to show the status of the device and the button can be used to change the status of the device. Thanks to the reporting done by the code, it allows to see the RSSI and RSSI 2levels of the connection, the number of packets sent and received, the number of errors and the packets that have been lost. Mesh networking The current version of the modem doesn’t implement mesh networking, as the upper layers of the protocol stack that allow this functionality are not implemented yet. To test this DECT NR+ functionalities, the Wirepass technology has been used, as it allows the implementation of the mesh networking in the technology. Wirepass implements the mesh layer above a BLE stack, therefore the obtained results need to be taken with caution, as the BLE stack is not 40 the same as the DECT NR+ stack, as explained in the section 2.4.4. For the use of the Wirepas solution, the PAN1780 Wirepas Mesh Demo Kit [Pan] has been used, which is based on the PAN1780 module from Panasonic. The test done in this section has been done only to show and the test the functionalities of a mesh networking application that has been promised by Wirepas to be implemented on top of the DECT NR+ technology. In other words, a showcase of the mesh networking capabilities that the DECT NR+ technology will have in the future. The obtained results have been positive, as the mesh networking has been implemented correctly and the devices can communicate with each other through the mesh network. It must be noted that the rage that this devices o!ered during the testing is of →80mand thanks to higher output power (23 dBm to 8dBm of the used device) and the lower frequency (1,9GHz to 2,4GHz of the used device) the range of the DECT NR+ technology is higher as shown in the later section 4.5.3. Conclusions It has been concluded that the limitation of only implementing the PHY and MAC layers of the DECT NR+ technology in the first devices doesn’t allow the correct implementation of the mesh networking,due to the upper layers of the protocol stack (Data Link Control and Convergence Layer [2.3.5]) are the ones responsible for this tasks. The point-to-point and point-to-multipoint communication have been tested and are working correctly, as the tested version of the modem provides the right resources that allow this functionalities. 4.4. RF Evaluation DECT NR+ being a wireless technology, the RF of the technology needs to be tested to check the correct use of the radio resource and the compliance of the device with the standard. Several experiments have been done to analyze the bandwidth, frequency, timing parameters, power transmission and channel characteristics of the DECT NR+ technology. 4.4.1. Test scenario The following equipment was used to analyze the RF of the DECT NR+ technology: •Tektronix RSA306 Real-Time Spectrum Analyzer [Tek]. •2 nRF9161DK devices [Nora]. The tests were conducted inside an o”ce space where the nRF9161DK devices were placed next to each other and 40 cms away from the antenna that was connected to the spectrum analyzer. The devices were connected to the computer and the perf tool was used to transmit 41 Figure 4.1.: 3D visualization of a spectrogram while a DECT NR+ transmission. data between the devices. The perf tool was set to transmit data for 10 seconds in the 1899,068 MHz frequency (Channel 1677 Band 1). 4.4.2. Bandwidth The form of the measured bandwidth can be seen in 3d in the figure 4.1 in 3d and in 2d in the figure 4.5. The bandwidth can also be also be observed in the figure 4.2 where the use of the radio frequency spectrum is seen during two 10 second perf transmission sessions. In all the measurements that were realized the nominal channel bandwidth corresponds to the one that is specified in the ETSI standard for DECT NR+ technology, which is 1,728MHz for the frequency of 1899,068MHz (Channel 1677 Band 1). Furthermore, it can be seen in both images how the signal follows the form of a transmission for a single e!ective antenna of two subslots duration, as described in 2.3.3, where the an unallocated guard signal is used in the center frequency of the channel and the synchronization, demodulation references, physical control and data channels are allocated next to them. The devices used for the testing have a maximum of a subcarrier scaling factor (µ) of 1 and a Fourier scaling factor (ω,) of 1. However, the bandwidth of the transmission could be widened if the modem allowed higher values of these particular parameters. As previously discussed when listing the limitations of the device, devices with higher capabilities should provide higher bw and data rates, as more bits would be transported. However, as revealed in a later section of this chapter, research has shown that higher bandwidth results in selective frequency fading behavior. 42 Figure 4.2.: 2D visualization of the DECT NR+ spectrogram while two perf transmissions. 4.4.3. Timing analysis As part of the experimental procedure, the count of consecutive slots has been changed in the perf transmission so the timing of the DECT NR+ frame and the subslots could be analyzed. The slot timing can be seen in the figure 4.3, in which a single slot can be seen that has a duration of Tslot =0,408571ms ↓0,41667ms. The results obtained here match the ones obtained in the theoretical calculations realized in the [21a]. During this testing it was also realized that the consecutive slots also changed the data rate as it used the available subslots more e!ectively. The e!ect of the correct selection of the amount of consecutive slots has been thoroughly examined in the 4.5.1 of the document. Also the use of too much consequent slots caused the devices to lose synchronization and, consequently, losing the entire communication. 43 Figure 4.3.: Amplitude vs Time visualization of a single DECT NR+ frame slot. 4.4.4. Power transmission For checking the correct output of the power of the device, the device has been connected to the spectrum analyzer in the way shown in the figure 4.4. The model designed for this specific test follows the one recommended by Nordic themselves [Norb], but an 3dB attenuator has been added to avoid any damage to the spectrum analyzer, as it has max input power range of +20dBm at the center frequency of ↔22MHz [Tek24]. The power of the device was measured in the spectrum analyzer and the results can be seen in the figures 4.5 and 4.6. The results of the power measurement can also be seen, in the table 4.3. The maximum output power of the device was measured to be 16,21dBm and the RSSI was measured to be ↑26,71dBm. The results obtained in the testing are in line to the expected ones, as the output power of the devices has been of 19dBm and the attenuator reduces the output by 3dBm. Table 4.3.: Power measurement results. Parameter Max measured output Max output [dBm] 16,21 RSSI [dBm] -26,71 44 Figure 4.8.: Diagram of the network scenario for the co-existence testing. In contrast, disabling LBT causes RDBA to interfere with both HARQ and non-HARQ transmissions. In HARQ scenarios, this interference overloads the RA (perf server), leading to communication failures. In non-HARQ scenarios, RDBA reduces the available data rate by half, as it transmits without verifying channel availability, thereby disrupting other devices. Activating LBT resolves these issues by ensuring that RDBA monitors the channel and transmits only when it is free. This behavior highlights the e!ectiveness of LBT in enabling coexistence and minimizing interference between devices operating within the same frequency channel. The results are summarized in Table 4.7. Table 4.7.: Summary of obtained results for the di!erent co-existence cases that were tested. HARQ LBT O”On O” Half the data rate compared to the max values Max values On Interferes and stops the server Max values 51 4.5.3. Range testing The DECT forum promises high range (up to several kilometers) and low power consumption, but the real values are needed to be tested to see if the technology can be used in the intended applications. The range testing has been done to check the range of the technology and to see if the technology can be used in the intended applications. Test Scenarion Figure 4.9.: Location of where the devices were located during the range testing. For the location of the test, the Technische Hochschule L¨ubeck campus has been selected, like in the radio planing modeling done in the section 3.3. The devices were running the 52 bidirectional ids.c code with the configuration showed in the table 4.8. Table 4.8.: bidirectional ids.c configuration for range testing. Parameter Value CONFIG CARRIER 1,677 MHz CONFIG NETWORK ID 91 CONFIG TX POWER 13 (19 dBm) [24] CONFIG MCS 1 2.3 CONFIG RX PERIOD S 3 CONFIG TX TRANSMISSIONS 3000 The location of the measurements that were taken can be seen in the figure 4.9. The server device was fixed in the roof of building 18 (colored red pin in the map) at a height of approximately 12 meters, meanwhile, another device was moved through the campus while connected to a computer so the measurements could be taken. Results The realized measurements show a maximum range of →200min a LOS (Line-of-Sight) scenario. The minimum, max and mean values of the RSSI and RSSI2 that were measured during the testing can be seen in the table 4 and 5. Compared to the radio planing results obtained in the section 3.3, around half the range has been achieved in the real testing. This is due to the fact that more power was configured for the transmitter in the simulation (23dBm) compared to the real testing (19dBm). It should be taken into account the fact that longer ranges could be obtained with another antenna that is not isotropic, and the development kit isn’t the ideal solution for long range testing, but the results give a true perspective of the range of two actual devices in a DECT NR+ network, as DECT NR+ is not intended to use in the convectional cell network where the base station can transmit at a higher power and the devices can be located further away. In addition, the weather and the environment can a!ect the range of the technology, as the technology is intended to be used in indoor environments in URLLC use cases, the range can be lower in outdoor environments. 4.5.4. Latency In this test the latency in has been measured in experimental/development cases. The latency is an important factor in the URLLC use cases, as the technology is intended to be used in real-time applications where the latency is crucial. The latency testing has been 53 done to see the latency that the technology can o!er and to see if the technology can be used in the intended applications. Test scenario For taking latency measurements, the timing of the devices needs to synced. Therefore, to achieve this the test scenario shown in the figure 4.10 has been designed and implemented. Two devices (RDAA and RDAB) are transmitting to each other using a modified version of the bidirectional ids.c known as latency/listening.c code where no unicode message is sent, and the broadcast messages are sent every 5 seconds after a time-o!of 5 seconds where the devices are listening to broadcast messages from a third RD (RDBA) that is running the broadcast.c code and broadcast messages to the neighboring devices. The broadcast messages sent by RDBA are used to sync the devices and to know when the devices are transmitting and receiving the messages. This model allows to surpass the limitation regarding the synchronization of the devices that the technology has os date of writing this document. For the configuration of the transmission,a study that assesses the candidature of this technology [Dha+20] emphasized the importance of meeting strict latency requirements for both the control and user planes. Interestingly, it was found that enabling HARQ-less transmission allows for compliance with these stringent requirements. However, when employing full slot transmission with HARQ, the user plane latency exceeded the critical 1ms threshold, indicating potential limitations in certain scenarios. Therefore a HARQ-less transmission was used in the test to see the latency that the technology can o!er. The devices are located next to each other, as the test is for checking the latency of the technology and not the range of the technology. Here are the parameters that have been used in the test: Table 4.9.: Latency Testing Parameters. Parameter Value Number of tests 4, one for each available MCS value Number of measurements 10 transmissions for each test Duration of each test 1 minute and 30 seconds NRF SDK version 2.7.0 Tool listening.c &broadcast.c Transmitted TX power 19 dBm Environment Inside an o”ce Frequency 1899,069 MHz (Band 1 channel 1677) 54 Figure 4.10.: Test scenarios designed for the latency testing. Results The results of the latency testing can be seen in the table 4.10. In the testing, a max latency value of 19,678 ±0,120 is achieved from the start of the transmission until the moment the data is available (pdc() function in the figure 4.11). Also, the results show that in the tested scenario the change of values of the MCS doesn’t drastically influence in the latency of the technology. Maybe even higher MCS values will lower the latency but that will create higher processing time and the devices will need more time to transmit the data. Compared to the promised theoretical values that are according to the transfer time needed, or propagation time of the signal, we can see a clear processing delay that is due to the processing time of the modems in the development kit. The devices that were used for the testing don’t run a fully functioning modem and are not intended to be used in a real network, but they are used for testing the technology and the functionalities that the 55 technology o!ers as they are the only devices capable of running the DECT NR+ technology. Future versions of the modem can optimize the functions that are responsible for the processing time and the latency of the technology and reducing the latency. Therefore, this test must be repeated with the new versions of the technology to see the latency that the technology can o!er with the new version of the modem. Table 4.10.: Result of latency testing. MCS DEV1->DEV2 DEV2->DEV1 PCC latency (ms) PDC latency (ms) PCC latency (ms) PDC latency (ms) 010,626 ±0,011 19,656 ±0,105 9,940 ±0,101 19,423 ±0,106 110,270 ±0,115 19,670 ±0,109 9,932 ±0,111 19,407 ±0,120 210,271 ±0,109 19,654 ±0,111 9,929 ±0,109 19,409 ±0,114 310,290 ±0,119 19,678 ±0,120 9,902 ±0,130 19,381 ±0,127 Figure 4.11.: Model of latency testing. 4.6. Research Due to the limitations of the first devices running the DECT NR+ technology, outside research has been collected in this selection of the document to provide a more complete view of the technology and its potential. This external research helps to highlight the technology’s potential performance under ideal conditions, providing benchmarks that maximize its capabilities. 56 Channel characteristics For the channel characteristic of the technology, the results are taken from the measurements done related to the performance and the channel soundings in the research paper called “Performance of DECT-2020 NR in an industrial environment for varying RF bands” (Wassmann, Poets, Peissig, & Pilz, 2024) for the EuCNC 6G Summit [Was+24], where they analyzed the channel characteristics of the DECT NR+ technology in an industrial environment by testing the DECT NR+ radio characteristic using GNU Radio [GNU] and Ettus USRP Software Defined Radio (SDR) devices [Res24]. Delay and doppler spread The research findings indicate that the RMS delay spread averages around 65 nanoseconds (ns) across all frequency bands, with a maximum of 180 ns observed at the 3700 MHz spectrum. This metric is crucial for understanding the channel’s behavior in terms of multipath propagation, which influences the system’s performance. Specifically, a larger RMS delay spread indicates a wider distribution of signal arrival times, potentially leading to inter-symbol interference (ISI). The observation of a maximum delay spread at the 3700 MHz spectrum suggests a more dispersive channel, highlighting the need for advanced signal processing techniques to mitigate ISI e!ects. Additionally, the spreading of the spectrum, dependent on the carrier frequency, determines the maximum Doppler frequency, impacting the system’s ability to handle user mobility. Lastly, the impulse response falling below the 20dB threshold before 1µs indicates a rapid decay of the channel’s e!ect on the signal, facilitating easier signal recovery and demodulation. These data points are essential for designing and optimizing wireless communication systems to ensure reliable performance under varying channel conditions. Channel soundings The research paper concludes that the 1.728 MHz bandwidth is below the coherence bandwidth of the channel, indicating a flat fading environment where the channel’s response is approximately constant across the signal’s bandwidth. In such a scenario, although CPOFDM is not strictly necessary due to the uniform fading, it is still beneficial for handling multipath propagation, which is common in real-world environments. Meanwhile, MIMO can e!ectively exploit spatial diversity to improve communication reliability in this flat fading channel. Conversely, at the highest tested bandwidth of 13.824 MHz, the channel exhibits frequencyselective fading behavior. In this case, CP-OFDM becomes particularly advantageous as it divides the signal into multiple subcarriers, each experiencing flat fading, thereby simplifying equalization and mitigating the e!ects of multipath fading. Furthermore, MIMO can be 57 employed in conjunction with OFDM to leverage spatial diversity, enhancing the system’s performance in the face of frequency-selective fading. Therefore, the PHY and MAC layer methods, including CP-OFDM, MIMO, and the FEC provided by HARQ, of the DECT NR+ technology are e!ectively deployed to address the fading e!ects of the channel across both flat and frequency-selective fading conditions. Range In the research by Nihtilae and Berg (2022) called “Energy Consumption of DECT-2020 NR Mesh Networks”[NB22], shows that the coverage area of the technology is dependent on the number of tiers or leaves in with a FT devices is used as a relay to the sink. The higher the tier the higher the coverage area, as it can be seen in the figure 4.12, but at the cost of increasing the delay and the energy consumption of the devices. Figure 4.12.: Percentage of nodes in di!erent network tiers with di!erent scenario radiuses [NB22]. Scalability In the research done by Roman Kovalchukov [Kov+22], demonstrated that DECT NR can achieve delay performance comparable to current technologies, despite supporting significantly higher node densities. This finding is crucial for understanding the scalability and e”ciency of DECT NR in real-world applications. It must be noted that the final submissions from ETSI DECT Forum to ITU-R lacks detailed specifications regarding the usage of mesh topology which was necessary to evaluate the supported connection density. The mesh network allows an extensive coverage of the area as the simulation results in [Dha+20] show, but this creates a delay in the packet delivery. 58 Energy consumption The research paper by Nihtilae and Berg (2022) called “Energy Consumption of DECT-2020 NR Mesh Networks” [NB22] investigates the energy consumption of DECT-2020 NR networks, especially concerning IoT applications where devices have limited battery capacities. It notes that routing responsibilities increase energy consumption among nodes. To counteract this, the paper discusses advanced physical layer technologies like CP-OFDM, turbo coding, and HARQ with incremental redundancy, aiming to reduce transmission times and boost energy e”ciency. However, comparing these technologies to past studies is challenging due to technological advancements. The study focuses on how varying the RACH period a!ects energy consumption. Notably, it excludes calculating the power consumption of sinks since they’re typically connected to the power grid. Adjustments to duty cycles significantly impact router battery life, highlighting them as the primary energy consumers in DECT-2020 networks. Reliability The reliability of DECT-2020 NR has been analyzed in various studies, including those referenced in “Assessment of Candidate Technology ETSI: DECT-2020 New Radio” (Dhanwani, Vishakha and Kumar, Navin and Bachkaniwala, Akhil Kalpesh and Rawal, Divyang and Kumar, Sendil, 2020) [Dha+20] and “Performance of DECT-2020 NR in an industrial environment for varying RF bands” (Wassmann, Mattes and Poets, Alexander and Peissig, Juergen and Pilz, Jens, 2024)[Was+24]. These analyses focus on the geometric Signalto-Interference-plus-Noise Ratio (SINR) distribution and the performance requirements for reliability. For instance, [Dha+20] highlights that due to poor geometric SINR distribution, the performance requirement of reliability for DECT-2020 NR was found to be marginally lower than the minimum requirements for IMT-2020. This suggests that DECT-2020 NR may struggle with single-frequency reuse deployments, indicating areas for improvement in future iterations of the technology. Moreover, [Was+24] provides insights into the reliability of DECT NR+ technology through measurements conducted with hardware that implements the technology. These measurements reveal packet error rates below certain thresholds across di!erent frequencies and numerologies, o!ering valuable data on the reliability of DECT NR+ under various conditions. However, it’s important to note that these measurements were limited by the capabilities of the testing hardware, as it didn’t implement the previously mentioned methods for ensuring high reliability. In summary, enhancing the reliability of DECT-2020 NR involves addressing challenges related to SINR distribution and leveraging advanced error correction and retransmission techniques. While current implementations show promise, ongoing research and development are essential to further improve reliability and ensure that DECT-2020 NR meets the 59 stringent requirements of next-generation wireless networks. Figure 4.13.: Bit and packet error error rates [Was+24]. 4.7. Summary The evaluation of DECT NR+ technology conducted in this thesis provides a valuable insight into its performance, capabilities, and current limitations. As one of the first empirical studies using hardware implementations, it o!ers a practical perspective beyond the theoretical and simulated expectations previously available in the literature. The testing confirmed that the DECT NR+ modem e!ectively supports point-to-point and point-to-multipoint communication. These implementations demonstrated stable functionality, validating the foundational aspects of the technology. However, the absence of upper protocol layers, particularly for mesh networking, remains a notable limitation. This shortcoming highlights the need for further hardware and firmware development to unlock the full potential of the DECT NR+ standard. Radio frequency (RF) evaluations a”rmed compliance with key specifications, including slot timing, bandwidth utilization, and power output. Despite these successes, the device’s restricted transmission bandwidth (1.728 MHz vs. a theoretical 6.912 MHz) and reduced output power (19 dBm vs. 23 dBm) constrained performance, particularly in the range testing where a range of approximately 200 meters has been obtained. Such findings underscore the developmental stage of the hardware and the necessity for more advanced implementations to meet the technology’s theoretical benchmarks. Performance metrics, such as data rates and latency, revealed promising results within the tested scenarios, showing the modem’s ability to handle reliable communication. Latency values, while acceptable for non-real-time applications, require further optimization to meet ultra-reliable low-latency communication (URLLC) standards. Co-existence testing demonstrated the e!ectiveness of DECT NR+’s Listen-Before-Talk (LBT) mechanism in minimizing interference, ensuring compatibility with other technologies operating in shared 60 Table 5.4.: Smart lighting configuration parameters. Parameter Value Reason MCS 0 Operates at lower signal-to-noise ratios and transmit with less power. More robust in poor channel conditions due to its larger constellation spacing HARQ On O!ers high reliability mechanisms LBT On Access control. It allows to avoid collisions and interference with other devices Consecutive slots 2Allows for a high density of devices within the network as it doesn’t saturate the radio channel receiver ID filtering from the latest available modem of the development kit [4.2.1], ensuring only the intended device processes the transmitted data while others ignore it. The centralized control mechanism enables the sink to e”ciently manage the lights, optimizing network operations. The solution’s functionality is illustrated in Figure 5. For deployment and testing, a simple scenario was designed using three DECT NR+ devices: one sink (Dev1) and two nodes (Dev2 and Dev3). During testing, the devices were spaced 30 meters apart from the sink. This space between devices has been selected to ensure URLLC requirements can be meet before deployinsg thanks to the results of the simulations conducted in the section 3.2 and also with the fact that the average distance between lampposts can be said that is around this value [Nat06]. The sink was activated first to ensure it could receive broadcast messages from the nodes as they powered on. However, the design accommodates nodes being activated before the sink, as the broadcast messages do not require confirmation. Once the first node was turned on, the sink detected its broadcast message and mapped one of its buttons to the node’s LED. The same process was repeated for the second node. To verify functionality, the user pressed each button on the sink, which successfully triggered the corresponding LED on the respective node. The test was conducted during →5 mins, pressing a di!erent button in the sink device every →10 seconds. The results demonstrated high reliability, with no loss of connection during the tests, and low latency, averaging just to just around 25 ms. These outcomes underscore the e!ectiveness of DECT NR+ technology in ensuring seamless communication and prompt response. This implementation highlights the potential of DECT NR+ for practical IoT solutions, o!ering a scalable and robust framework for smart lighting and similar applications. 67 Un-centralized control For this second implementation, a scenario where any device of the network can control the lights of all the devices in the network has been designed and developed. In this case, when a user presses a button in a node that node broadcasts a signal informing of the bottom of the device that has been pressed, triggering each device to illuminate the specific light corresponding to the pressed button. This solution enables the lights of all devices within the network to be controlled simultaneously, enhancing the user experience and operational e”ciency. The functionality of the solution can be seen in the figure 6. All the device in the network run the src/light control broadcast.c program [Jau]. For the testing, the same scenario as for the centralized control was used, with the same devices and the same distance between them (30 meters). The test was conducted during →10 mins, pressing a di!erent button of a di!erent device every →25 seconds. The results of the testing have shown high reliability, where the connection wasn’t lost and all the commands were sent correctly. Moreover, low latency (average of 25 ms) was also achieved thanks to the correct configuration designed previously done for the devices. 5.5. Summary The simulations and detailed performance analysis conducted in this thesis have provided valuable insights into the capabilities and limitations of the first generation of DECT NR+ devices. While these devices do not yet fully support the stringent requirements of URLLC and mMTC use cases—the primary targets of the technology—they have demonstrated su”cient reliability and low latency for less demanding applications. This is exemplified by the smart lighting use case for smart cities developed in this thesis, which highlights the technology’s potential to deliver practical solutions even in its current form. Despite the current hardware limitations, DECT NR+ introduces innovative features and a flexible architecture, positioning it as a strong contender for future IoT applications. As the technology matures and more advanced devices become available, its ability to meet the full spectrum of 5G mMTC and URLLC requirements is expected to improve, enabling increasingly complex and scalable solutions. Furthermore, the implementation of higher layers of the DECT NR+ architecture natively within device modems —through future updates— will unlock advanced features such as mesh networking and IP support, as outlined in the standard, facilitating even more sophisticated IoT applications. 68 6. Conclusions This thesis provides a comprehensive analysis of DECT NR+ technology, focusing on its scalability and performance potential in real-world IoT applications. The research conducted for this thesis demonstrates that DECT NR+ incorporates advanced specifications and techniques (e.g., HARQ, LBT, CP-OFDMA) designed to theoretically meet the requirements of the new use cases for which the next generation of wireless mobile networks was developed for. Comparative analysis with other LP-WAN technologies reveals that DECT NR+ is designed to achieve high data rates and long-range coverage, leveraging its mesh networking capabilities and e”cient use of the frequency spectrum. Simulations and modeling conducted during the thesis provided valuable insights into DECT NR+’s scalability and radio planning capabilities, generating crucial data for potential deployment scenarios. Specifically, the impact of device distance and mesh network size on communication latency was simulated and analyzed, identifying network specifications that enable Ultra-Reliable Low-Latency Communication (URLLC) use cases. Real-world tests conducted to evaluate the performance of the initial batch of DECT NR+ devices revealed specific limitations, particularly in supporting URLLC and massive Machine-Type Communications (mMTC) use cases. These limitations were primarily due to constraints in mesh networking functionalities, latency, and bandwidth specifications. Nevertheless, the devices demonstrated su”cient capabilities for innovative applications, such as the smart lighting solution developed in this thesis. Although the initial devices exhibit limitations, the findings indicate that DECT NR+ holds significant promise within the evolving landscape of communication technologies. Enhanced devices with improved capabilities could overcome these initial constraints, unlocking the full potential of DECT NR+ and o!ering advanced mesh networking capabilities, such as self-healing, decentralization, and autonomy—features not supported by the devices used for evaluation. In conclusion, this work provides a foundational understanding of DECT NR+ technology and highlights the need for ongoing research. As advancements continue and more capable modems are developed, the work presented in this thesis can serve as a base for future research, with the software programs created during this study being repurposed for further investigations. This will be essential for fully exploring the opportunities presented by DECT NR+, ensuring its viability in addressing the complex demands of modern communication networks. 69 1. Appendices A. Collected data from the testing In the following tables the collected data from the testing is shown. The data is divided into di!erent tables depending on the type of data that was collected. Table 1.: Data rate (kbit/s) testing comparison between di!erent MCS values with default values (2 consecutive slots) MCS Data rate MCS no HARQ MCS with HARQ Min Average Max Min Average Max 0240,52 240,632 240,80 57,29 57,297 57,36 1482,29 494,674 496,05 118,02 118,02 118,02 2642,57 737,208 756,11 179,89 179,89 179,89 3609,44 966,83 1006,54 239,47 239,47 239,47 41497,78 1497,78 1497,78 356,34 356,34 356,34 Table 2.: Max obtained data rate (kbit/s) testing comparison between di!erent MCS values MCS/Slots Data rate MCS no HARQ MCS with HARQ Min Average Max Min Average Max 0/8 479,18 480,741 481,07 202,08 202,08 202,08 1/8 956,34 956,34 956,34 401,72 401,72 401,72 2/7 1379,71 1380,892 1381,25 476,85 476,85 476,85 3/5 1642,1 1642,1 1642,1 458,81 475,01 485,81 4/4 2185,12 2228,688 2250,08 717,42 718,357 718,67 70 Table 3.: Bandwidth e”ciency for each obtained max data rate MCS / Slots MCS no HARQ MCS with HARQ Avg data rate BW e!ciency Avg data rate BW e!ciency 0 / 8 480,741 0,031 202,08 0,013 1 / 8 956,34 0,062 401,72 0,026 2 / 7 1380,892 0,09 476,85 0,031 3 / 5 1642,1 0,107 475,01 0,031 4 / 4 2228,688 0,145 718,357 0,047 71 Table 4.: RSSI values testing comparison between di!erent distance ranges. Distance (m) RSSI Error count1 Min Avg Max 20,00 -55,0 -51,05 -48,5 0 26,38 -65,5 -61,2 -57,5 0 30,00 -69,5 -65,05 -63 0 30,15 -72,5 -68,75 -65,5 0 52,63 -65,0 -64,15 -63 0 78,36 -69,0 -65,45 -61,5 0 81,54 -64,5 -63,45 -63 0 107,01 -66,0 -65,15 -64 0 128,31 -74,0 -70,71 -69,5 3 131,27 -72,0 -71 -70 5 135,29 -65,5 -64,55 -63,5 0 151,03 -75,0 -74,1 -73,5 5 155,66 0 0 0 10 160,87 0 0 0 10 161,23 0 0 0 10 162,61 -73,5 -73,08 -73 4 166,79 0 0 0 10 179,76 0 0 0 10 184,15 -73 -71,18 -69,5 2 192,15 -72 -71,75 -71,5 6 195,32 -73 -73 -73 1 200,15 -73 -71,72 -70,5 1 201,26 0 0 0 10 72 Table 5.: RSSI 2 values testing comparison between di!erent distance ranges. Distance (m) RSSI 2 Min Avg Max 20 -110 -104,75 -97 26,38 -131 -118,47 -111 30 -140 -134,2 -126 52,63 -130 -127,57 -126 81,54 -127 -126,27 -125 128,31 -150 -142,92 -139 162,61 -153 -148,4 -145 195,32 -146 -145,7 -145 192,15 -150 -145,88 -143 30,151 -155 -142,22 -131 78,36 -138 -90,51 -17 107,01 -132 -130,25 -128 151,03 -152 -149,29 -147 184,15 -151 -144,17 -138 131,27 -151 -145,40 -140 155,66 -157 -154,48 -152 160,87 -157 -153,46 -150 135,29 -131 -128,45 -127 161,23 -158 -155,1 -152 166,79 -152 -149,44 -147 179,76 -158 -151,87 -144 200,15 -158 -154,5 -151 201,26 -158 -154,5 -151 1Error count out 10 measurements 73 Table 6.: Ethertronics P822601 Electrical Specifications [Eth]. Frequency (MHz) 698-960 1710-2200 2500-2700 Peak Gain 2.6 dBi 4.4dBi 3.4dBi Average E!ciency 68% 76% 52% VSWR Match <2.5:1 Polarization Linear Power Handling 2 Watt CW Feed Point Impedance 50 #unbalanced Figure 1.: Amplitude vs Time visualization of two DECT NR+ frames with 2 consequent slots and 2 slot gaps. Figure 2.: Amplitude vs Time visualization of two DECT NR+ frames with 8 consequent slots and 2 slot gaps. 74 Figure 3.: Amplitude vs Time visualization of a single DECT NR+ frame slot with 8 consequent slots and 2 slot gaps. 75 B. Flow charts of the code developed for thesis Figure 4.: Flow chart of the bidirectional ids.c code. 76