What you’ll learn:
- The four main elements of LoRa network architecture.
- Some of the common challenges faced by designers while developing LoRa end nodes and how to work around them.
- How regulatory certified LoRa modules helps overcome these challenges and reduces time to market.
远程（Lora）技术通过将长距离无线连接与低功率性能相结合，从而扩展了物联网（IoT）的范围。从智能城市到智能农业再到供应链跟踪，洛拉是创建可以在城市和农村环境中运作的灵活的物联网网络的理想选择。但是，开发新的洛拉解决方案或迁移到一个方案有多容易？
Understanding a new wireless technology and choosing the right solution for your application can be exhausting. Wireless radio-frequency (RF) design usually requires in-depth RF expertise and adds significant development time for designers.
Lorawan网络体系结构
LoRa is a wireless modulation technique or physical layer that allows low-power end-devices to communicate over long range. LoRaWAN—a wireless networking protocol that acts as a media-access-control (MAC) layer—is implemented on top of the LoRa physical layer. The LoRaWAN specification details the communication protocol and network architecture and is meant to provide secure communication of end-devices and interoperability within the network.
The LoRa network has four elements(Fig. 1):
- End-nodesare elements of the LoRa ecosystem that gather sensor data and transmit/receive the data. They’re generally remotely connected and are battery-powered.
- The网关is a transparent bridge between the end-nodes and network server. Typically, end-nodes use LoRaWAN to connect to the gateway, while the gateway uses high-bandwidth networks such as Wi-Fi, Ethernet, or cellular to connect to the networks.
- Anetwork serverconnects to multiple gateways. It gathers data from the gateways and filters out duplicate messages, decides which gateway should respond to end-node messages, and adapts data rates to extend battery life of end-nodes.
- The应用程序服务器从结束节点收集数据并控制活动ons of the end-node devices.
Let’s take a closer look at LoRa end-nodes and the challenges in designing them.
Common Challenges in Designing LoRa End-Nodes
End-nodes are simple objects, such as sensors and actuators. Typically, they comprise the “things” within the Internet of Things (IoT). In the LoRaWAN ecosystem, an end-node communicates to the network server through one or many gateways.
LoRa end-nodes are typically low-cost battery-powered applications that need to be power-efficient. Depending on the development time, target costs, power consumption, and RF expertise available, several options are available to build LoRa end-nodes. Before researching those options, let’s look at some of the most common challenges that designers face when designing end-nodes. They include:
RF Design
As with any wireless design, significant RF design expertise is needed when designing LoRa end-nodes. When using LoRa systems-on-chip/systems-in-package (SoCs/SiPs), the end-node device developer is responsible for the entire RF design, including schematics, bill of materials (BOM), PCB layout, antenna tuning, and other RF hardware.
Even with the best documentation and application design guides, RF design isn’t always easy. It not only requires in-depth RF expertise, but also adds up significant development time for designers. Furthermore, debugging RF designs most often requires special equipment, adding further to the development costs.
为了克服RF设计挑战,一些suppliers offer SoCs/SiPs that are supported by excellent documentation, regulatory certified reference designs, and detailed chip-down design packages. However, for the shortest development time and reduced risk, an RF optimized, tested, and certified LoRa module is almost always the best choice. These modules can provide a complete solution as a single component reducing design risk and development times.
Regulatory Compliance and Certifications
LoRa/sub-GHz radios typically operate in the ISM license-free band. The frequencies vary depending on the region, making it challenging for hardware and software designers. Diligent care must be taken to design a fully compliant solution while keeping the BOM costs minimal. Also, RF regulatory requirements are constantly changing. Thus, keeping up with the regulatory changes, re-testing the devices, and re-certifying for compliance can cost several thousands of dollars—as well as engineering time—for end-node developer companies, money and time that could otherwise be spent on new projects.
Using a certified LoRa module solves this issue easily; the module manufacturer takes care of keeping up with the regulatory requirements and re-certifying modules to the latest specifications. All of these costs and time spent on regulatory compliance can be completely avoided by choosing a regulatory certified LoRa module.
多区域操作
洛拉设备根据区域支持几个频率。末端节点制造商通常首先在一个主要地区释放其最终产品。一旦需求加剧，公司会调查在其他地区扩展相同设计的情况。拥有一个支持多个地区的单个SKU可以使最终产品无缝移民和扩展到不同的国家和地区。适用于多个频段的监管认证的LORA模块是此类产品扩展的理想选择。
强大的软件
Generally, LoRa modules integrate the whole LoRaWAN stack inside the module. The end-node developer only needs to implement the initialization and communication to the module. With LoRa SoCs/SiPs and with standalone LoRa modules, the stack must either be provided by the manufacturer, or the developer must develop its own stack if no stack is provided.
To minimize software development, it’s recommended to choose LoRa modules/ICs that are supported by the manufacturer’s LoRaWAN stack. Proven LoRaWAN stacks from manufacturers ensure interoperability of end-nodes with major LoRaWAN networks and gateways, enabling end-nodes to work across different networks with reduced risk.
从模块到SOCS的迁移路径
Many companies start their prototypes and initial production runs with certified modules to reduce risk and get their products faster into market. Once their product starts to ramp up, companies may decide to move to LoRa SoCs/ICs for increased flexibility or lower BOM costs. The migration isn’t always easy, so it’s very important to consider standalone modules that allow for simple software migration between the modules and ICs. Also, it’s essential to choose suppliers that sell both modules and SoCs; therefore, the development platform, software migration, and support structure remain the same.
Regulatory Certified LoRa Modules Simplify LoRa End-Node Designs
LORA模块由所有必需的无线电组成以及Lorawan堆栈和RF电路组成，从而有助于加速Lorawan终端设备的发展。由于RF开发和认证是由模块制造商实施的，因此制造商完全处理了认证规格或组件更换的任何更改，节省了大量的开发时间以及对最终设备制造商的重新认证成本。
具有高度集成的Lora IC的独立Lora模块提供了足够的内存，可以与Lorawan堆栈一起运行应用程序代码。这消除了对外部微控制器的需求，从而节省了板空间和系统成本。Figures 2和3show a simple example of such a standalone module.
TheWLR089U0基于SAM R34/35 IC家族的模块微芯片技术is a compact module with 256 kB of flash and 40 kB of RAM, making it well-suited for space-constrained applications. Also, the module includes an integrated RF switch, enabling multi-band operation and allowing the same module to be used across multiple geographies, facilitating market expansion for end-products. The WLR089U0 also is supported by Microchip’s LoRaWAN stack and proprietary peer-to-peer software, easing the software development for end-users developing LoRa applications.
Because the modules are based on the SAM R34/35 ICs, the migration path from modules to ICs and vice versa also is much simpler. Choosing such a module helps overcome all of the common design challenges while developing LoRa end-nodes, easing the entire design process.
Conclusion
Developing LoRa end-nodes can be complex and time-consuming. Highly integrated, certified LoRa modules provide an easy and proven approach to overcome the complex challenges involved in designing these end-nodes. Reliable software, larger memory, integrated RF switches, and regulatory certifications are some of the key features to look for in LoRa modules. Choosing a highly certified LoRa module not only helps simplify the design process, but also enables end-node developers to successfully differentiate their products and release them to market faster.
