5G standard enabling large-scale IoT deployment
5G networks have become the most important direction for wireless communication development. The world's first non-cellular 5G technology, DECT NR+, was standardized by the ETSI organization in 2020 and subsequently adopted as a 5G standard in 2022, recently attracting industry attention. The DECT NR+ standard may be a crucial key to large-scale Internet of Things (IoT) deployments. This article will introduce the development and characteristics of the DECT NR+ standard, as well as related solutions offered by Nordic Semiconductor.
5G standard using non-cellular technology
In the past, DECT technology was an abbreviation for Digital Enhanced Cordless Telecommunications, primarily used in wireless telephone systems. DECT NR+ (or technically known as the DECT-2020 NR standard) is the first non-cellular technology ever incorporated into the ITU-R definition of 5G standards. The DECT-2020 NR standard was developed by the ETSI organization to meet the ITU-R requirements for 5G technology (formally known as the IMT-2020 requirements).
DECT NR+ supports point-to-point, star, and mesh topologies. It's important to note that the mesh topology discussed here is an incomplete mesh topology, called a cluster-tree topology. This means that devices are grouped into several independent trees called clusters. A cluster-tree topology is a star topology that includes branches. All clusters are connected to form a mesh network, which is the incomplete mesh mentioned earlier, because not all nodes are interconnected as in a full mesh topology.
A DECT NR+ node can function as a sink node, relay node, or leaf node. A sink node acts as a gateway to the internet; it selects its operating frequency and initiates beacon frame transmissions, indicating that it has a route to the outside world. A network can have multiple sink nodes connected to the outside. Relay nodes extend the network by routing information to leaf devices in other clusters and within their own cluster. Leaf nodes are the outermost nodes in the network and can only transmit data.
In point-to-point and star topologies, nodes with internet backhauls are defined as sink nodes, and all other nodes are defined as leaf nodes connected to the sink node. Mesh topologies are more complex; this mechanism autonomously assigns device roles based on network needs, supports "self-organization" and "self-healing" of the network topology, and can resolve congestion issues under high traffic conditions. Each device independently determines its next hop based on available routes to the sink node, meaning the cluster tree forms autonomously.
As a DECT technology, DECT NR+ can use the unlicensed 1.9 GHz DECT band, which is globally exclusive, except for a few regions (China, India, Japan). The DECT Forum is working to expand its use.
DECT NR+ can coexist with classic DECT in the DECT band. Because DECT NR+ was designed for coexistence, it can also use the ISM band. In fact, the standard supports multiple licensed and unlicensed bands from 450MHz to 6GHz.
Solutions for large-scale IoT deployments in smart cities
The 5G standard defines three separate use cases for 5G technology services, including Enhanced Mobile Broadband (eMBB), which focuses on providing faster data rates and greater network capacity compared to previous generations of mobile networks. Additionally, there's Massive Machine-Type Communications (mMTC), designed to connect large numbers of low-power devices and sensors, emphasizing low power consumption, high density, and scalability. Finally, there's Ultra-Reliable Low-Latency Communications (URLLC), designed to provide extremely low latency and ultra-high reliability for mission-critical communications and applications requiring real-time response and mission-critical reliability.
mMTC can meet the need to connect a large number of low-power devices and sensors, which is relevant to many fields such as smart cities, agriculture, manufacturing, and healthcare. Technologies that meet the use case requirements specified by ITU-R must support several characteristics, including high density (1 million devices per square kilometer), long battery life, and asynchronous access.
On the other hand, URLLC emphasizes ultra-low latency and ultra-high reliability for mission-critical communications where data must be transmitted instantly and failures are not permissible. URLLC use cases enable low-latency systems to consider wireless operation for the first time, providing the low latency and reliability previously only achievable with wired connections. Applications include autonomous robots, power distribution, motion control, and more.
Currently, there is little convergence among individual IoT technologies because "there is no perfect standard for each application." For example, LTE-M and NB-IoT cellular IoT aim to provide long-range LPWAN and reduce latency requirements, but they use licensed spectrum, resulting in data costs. LoRaWAN, on the other hand, requires building expensive infrastructure. The lack of tailored wireless solutions makes the design of things like smart streetlights complex, cumbersome, and expensive. This makes it difficult for budget-constrained city authorities to quickly and easily deploy low-cost, wireless M2M technologies for smart lighting and other smart city applications, such as smart trash cans, micromobiles, public transportation, delivery tracking, etc., applicable to millions to billions of end devices. None of these technologies can perfectly meet these requirements.
A solution for smart cities has emerged, and DECT NR+ is well-suited for large-scale smart city IoT applications. It is a single, secure, and reliable radio standard that supports a multi-vendor ecosystem, is future-proof, and scalable. Furthermore, because DECT NR+ uses unlicensed radio spectrum allocation, it incurs no data fees, making its operating costs lower than licensed counterparts. DECT NR+ promises to enable the widespread adoption of 5G wireless, allowing for large-scale device deployment and possessing all the advantages of cellular technology, but at a significantly lower cost for large-scale IoT applications.
Highly integrated solution supporting DECT NR+
Nordic recently expanded its wireless portfolio with a new SiP product line for cellular IoT and DECT NR+ facilities. This new end-to-end cellular IoT solution, the nRF91 series SiP, includes three nRF91 series SiPs (two new devices, the nRF9161 and nRF9131), evaluation and development tools, development software, nRFCloud services, and technical support. Nordic is committed to providing complete design and deployment solutions for IoT enterprises. Nordic's design, support, chipsets, modules, software, and services deliver ease of use, stability, and cost efficiency, marking the first time a single company has offered a comprehensive cellular IoT solution.
The nRF91 series uses the Arm Cortex-M33 as its dedicated application processor, which is fully programmable by the user. It features 1MB of flash memory, 256kB of RAM, and a variety of peripherals. In addition to LTE connectivity and positioning capabilities, the series supports a wide range of applications and enables true edge computing possibilities for cellular IoT and DECT NR+ (nRF9161 and nRF9131 only). Nordic also provides the open-source nRF Connect SDK (Software Development Kit), which allows users to develop their custom applications on the dedicated application processor. However, note that the nRF9131 mini SiP does not integrate a PMIC, passive components, or crystal.
The nRF91 series is a fully integrated cellular IoT solution supporting LTE-M and NB-IoT applications. Its energy efficiency innovations make a significant contribution to power saving in both LTE-M and NB-IoT, namely eDRX (Extended Discontinuous Receiver) and PSM (Power Saving Mode). eDRX and PSM work together to enable battery life of months and years. The nRF91 series also supports Quality of Service (QoS), which can control and guarantee the performance and reliability of communications in these bands, and minimize power waste caused by interference between devices.
The nRF91 series boasts high deployment density and wide coverage, meaning it can be deployed at truly large scale and high density. The nRF9160 also incorporates important additional security measures to further enhance device security, including Arm TrustZone and Arm CryptoCell for secure and trusted execution and key generation and storage, providing optimal security.
High integration using system-level packaging
DECT NR+ Solution
Nordic's nRF9161 System-in-Package (SiP) is designed for cellular IoT and DECT NR+ applications, setting a new standard for highly integrated SiP solutions. Leveraging low-power LTE technology, advanced processing capabilities, and robust security features, the nRF9161 delivers outstanding performance and versatility. Compared to its predecessor (nRF9160), it features several enhancements, including support for DECT NR+ and 3GPP Release 14 LTE-M/NB-IoT.
The nRF9161 features several enhanced features, including support for DECT NR+ and the 3GPP Release 14 LTE-M/NB-IoT LTE protocol stack, offering global connectivity and high efficiency. Its integrated modem enables geographically unrestricted global connectivity and includes new and unique modem functions, further improving energy efficiency and ease of use. To fully unlock the potential of DECT NR+, the nRF9161's DECT NR+ protocol stack support enables secure, long-range, and scalable large-scale mesh applications.
Nordic's other offering, the nRF9131 Mini SiP, is a powerful solution perfectly suited for DECT NR+ applications. It also utilizes the same LTE stack as the nRF9161 to support cellular communication operations. The nRF9131 simplifies traditional chipset-based designs, making it ideal for high-volume cellular IoT applications. Compared to the nRF9161 SiP, the nRF9131 has lower integration and a lower bill of materials (BOM) cost. However, it's important to note that non-recurring expenses (NREs) for cellular terminal product certification will increase depending on the required geographic coverage. Therefore, the nRF9131 Mini SiP is well-suited for global NR+ applications as well as high-volume cellular products targeting specific regions.
The nRF9131 is perfectly suited for DECT NR+ applications, offering superior performance and functionality in these applications. Its smaller size and flexible sourcing options, coupled with its smaller footprint compared to the nRF9161, allow for compatibility with PMICs offering additional features. Furthermore, the nRF9131's firmware is fully compatible with the nRF9161, facilitating easy conversion between the two SiPs. Nordic also provides reference designs for the nRF9131, which can be used with Nordic's nPM6000 PMIC, offering similar power consumption to the nRF9161.
Conclusion
DECT NR+ promises to provide massive IoT access for large-scale M2M applications in markets such as industry, agriculture, asset tracking, smart cities, and smart energy, with low cost per node and a robust, efficient self-organizing network, making its market potential extremely promising. Nordic has a history of early adoption of key wireless technologies for rapid commercialization and was one of the first companies to bring DECT NR+ commercial solutions to market. Nordic's nRF91 series can assist customers in supporting the rapid development of DECT NR+ applications and is worth exploring further.
