LoRa networks resolve the age-old wireless dilemma in which engineers had to either choose longer range or lower power consumption. LoRa allows designers to maximize range and minimize power usage and thus reduce the cost of additional repeaters. So, millions of LoRaWAN sensors are under deployment for smart grid, smart metering, and asset tracking applications.
The LoRaWAN protocol is becoming a popular vehicle for connecting things of the Internet of Things (IoT) across distances of 10 miles or more while keeping batteries alive for many years. It’s even allowing independent designers and hobbyists to create connectivity solutions for tracking, positioning, metering, and many other applications (Figure 1).
By the close of 2019, suppliers of LoRa solutions have streamlined the availability of the key building blocks, broadly segmented into LoRa nodes or end devices, LoRa gateways, and LoRa network and application servers. And how they are simplifying the creation of long-range wireless networks for IoT and M2M applications serving smart cities, energy management, building automation, and more.
This article will expand on the key building blocks and how these components, along with the rapidly emerging LoRa-centric ecosystem, simplify the overall design process, accelerate the deployment of LoRa nodes and gateways, and seamlessly connect them with the LoRa network servers.
LoRa Node Design
The LoRa nodes or end devices usually operate in two modes: sleep mode when the node is idle and operation mode for wireless data transmission. And multiple sensors can be connected to a LoRa node to address power and space constraints.
An array of pre-integrated solutions allows developers to create LoRa nodes for a variety of IoT applications in areas ranging from smart agriculture to industrial automation to security and surveillance.
The LoRa end-device design, for instance, is now aided by highly integrated system-in-package (SiP) solutions. Take the example of Microchip’s SAM R34/35 SiPs, which allow designers to create remote IoT nodes while employing certified reference designs and interoperability with major LoRaWAN gateway and network suppliers.
The SAM R34/35 SiPs comprise an ultra-low-power 32-bit MCU, sub-GHz RF transceiver, and software stack (Figure 2). The UHF transceiver supports LoRa as well as FSK modulation schemes; FSK modulation ensures support for IEEE 802.15.4g, WiSUN, and legacy proprietary networks. The SiP device can transmit maximum power of 20 dBm.
These nodes feature sophisticated monitoring functions to serve specific application needs and require minimum design effort to interface with LoRa gateways. Moreover, the hardware solutions feature network drivers and reference designs for improved RF performance.
LoRa Gateway Design
LoRa gateways act as packet forwarders to pass the data coming from LoRa nodes to reach LoRaWAN network servers. They usually comprise baseband transceivers and sub-GHz RF front-end, and like LoRa sensor nodes, they are available as modules. That simplifies the development of gateways with out-of-box compatibility for both privately managed LoRa networks and public domain LoRa infrastructure for broader coverage footprint.
The LBAA0ZZ1 series LoRa Pico Gateway module from Murata is a case in point. The LoRaWAN gateway module is made up of four key building blocks. First, there are two RF front-end I/Q transceivers from Semtech, and these SX1257 transceivers process packets from remotely dispersed endpoints with the help of a Semtech SX1308 transceiver concentrator.
Next, STM32F401, an Arm Cortex-M4 microcontroller from STMicroelectronics, handles packet forwarding, communication with the application host controller, and the module’s power management functions. Finally, an RF front-end multi-chip module from Skyworks provides antenna matching, receiver pre-amplifier, and final stage transmitter functions.
The gateway modules also come integrated with LoRaWAN protocol stack, which allows designers to easily and quickly connect with LoRa networks mushrooming around the globe. Then there are cloud-based software and services that further simplify the creation of LoRa-based IoT applications.
And that brings us to the final piece of the LoRa design story: ecosystem.
The LoRa development chain includes gateway and end-node boards, firmware, and tools. The node and gateway boards usually come with an antenna and on-board debugger. One of the major developments in LoRa’s ecosystem domain is the launch of the Firmware Update Over The Air (FUOTA) specifications from LoRa Alliance.
The FUOTA specifications simplify the application-layer updates as well as RF stack updates to connected devices in the field. So far, LoRa Alliance has published three FUOTA specifications relating to application layer clock synchronization for time synchronization, remote multicast setup for sending messages to groups of end devices, and fragmented data block transport for data-file splitting.
STMicro, one of the early entrants into the LoRa market, has upgraded its software support package to accommodate the latest FUOTA specifications, allowing LoRa developers using endpoint devices with STM32 microcontrollers to take advantage of new firmware versions. The I-CUBE-LRWAN software package (Figure 4) includes the LoRaWAN stack with hardware abstraction layers and sample application code for the company’s STM32L0, STM32L1, and STM32L4 microcontrollers.
Likewise, on its LoRa-based modem, Murata is integrating Semtech’s LoRa Cloud Device & Application Services, a set of features aiming to simplify the provisioning of devices across LoRaWAN-based networks. The production-ready LoRa-based hardware platforms and associated cloud services allow developers to focus on IoT applications without worrying about underlying radio connectivity.
The year 2019 has witnessed a healthy adoption of LoRa devices and RF technology. And the quickly maturing design ecosystem could be a harbinger of LoRa’s credentials for an enabler of IoT-as-a-service in 2020.