First generation (‘1G’) cellular communications debuted in the 1970s. Analog systems handled the traffic and the handsets were cumbersome and expensive. But the idea caught on and by 1990 the number of global subscribers reached 20 million. Fast forward 28 years and according to the GSMA, an organization that represents the interests of mobile operators, the subscriber base has just passed five billion. And the latest generation of cellular technology, 4G LTE, now reaches over 50 percent penetration in over 70 countries around the globe and supports inexpensive high-definition streaming services that couldn’t have even been imagined a decade ago.
The prolonged gestation and maturation of cellular has allowed engineers to optimize the technology to meet consumer and commercial demands of ubiquity, reliability, security, and ease-of-use. It has also given carriers the revenue and time to build and enhance the huge infrastructure required to support global coverage.
Cellular technology offers better coverage than any other wireless technology. Its reliability comes from the years of constant technical refinement and is underwritten by fierce competition among the carriers. Security — a major consideration for engineers building wireless systems
— is an end-to-end priority for cellular networks. And high throughput
is built-in to meet the demands of millions of subscribers accessing streaming video and other data-intensive services. These strengths
are reinforced by the high quality of service (QoS) that comes as a consequence of the regulation, licensing, and management of
spectrum allocations used for cellular communication.
The advantages of cellular technology have attracted the interest of engineers tasked with building the Internet of Things (IoT). Cellular promises a solution for either directly connecting the IoT sensors of long-range, low power wide area networks (LPWANs) to the Cloud or forming LPWANs that facilitate gateways to the Cloud for local area networks (LANs) powered by short-range wireless technologies such as Bluetooth Low Energy (Bluetooth LE) or Thread. But there’s still some work to do before the vision turns into reality.
Extending cellular’s reach
High-throughput cellular technology is extremely complex and expensive, and the hardware is bulky and power hungry. Consumers are willing to bear the cost and recharge their handsets daily because the technology provides seamless access to the services they crave. But for IoT engineers, high- throughput cellular technology’s cost, complexity, and power consumption drawbacks make it tough to build the networks of hundreds of compact, battery-powered sensors that will underpin the IoT.
Cellular modems have found a niche for connecting expensive remote assets to the Cloud. For example, rural Intelligent Electronic Devices
(IEDs) used to control smart electricity distribution grids routinely send information back to a control centre. And operators of commercial equipment like vending machines (sited in public places such as rail stations) can cut operating costs by using a cellular modem to send information back to HQ rather than dispatching a service operative to manually check stock levels. Cellular modems are also popular with security companies who can’t take chances with less reliable wireless technologies such as Wi-Fi.
But these devices are unsuitable for IoT applications. First, many use legacy 2G networks which are being phased out — the spectrum allocations are used inefficiently and are sorely needed for 4G and forthcoming 5G traffic — and will have virtually disappeared by 2025. Second, cellular 2G, 3G, and 4G LTE modems are expensive, bulky, and power hungry because they have been designed to meet 3rd Generation Partnership Project’s (3GPP) specifications for higher category (higher throughput) operation.
Recognizing the drawbacks of traditional modems for the unique, low-cost, -throughput, and -power demands of the IoT, the 3GPP extended the modem categories to include LTE-M and NB-IoT in Release 13 of its specifications in 2015. Such a move encouraged the development of 4G LTE modems for IoT applications - applications that were impractical when based on higher category units.
Designed for the IoT
For the last three years, Nordic Semiconductor’s Finland-based engineers have combined their LTE expertise with the company’s Norwegian engineers’ ultra low power wireless know-how to design an optimized cellular IoT solution complying with the 3GPP’s LTE-M and NB-IoT specifications.
The result is the nRF91 Series System-in-Package (SiP), a low power, ultra compact cellular IoT solution. Because it has been designed to meet the unique demands of the IoT, the product’s designers have adopted a completely different approach to that employed for conventional cellular modules and have added a host of features never before seen in the cellular market.
For example, the nRF91 Series SiP integrates into a 10 by 16 by 1mm package a powerful ARM Cortex M33 application microprocessor, full multimode LTE modem and transceiver, RF front end from Qorvo, power management, Flash and RAM, plus crystal and passive components. Through this high integration and its precertification for global operation, the nRF91 Series SiP overcomes the drawbacks of cellular for LPWAN deployments as well as satisfying the comprehensive set of qualifications needed to employ cellular technology.
Nordic pioneered simple wireless development and implementation with its Bluetooth LE solutions. There the company masked the underlying complexity of RF engineering by supplying complete single-chip (radio
plus processor) wireless hardware and factory-supplied RF protocol stacks. Development was eased by offering tools that used familiar design environments for application engineering and code compilation while keeping the RF protocol stack separated from the application software. Such an approach has enabled thousands of developers who lack RF knowledge to create innovative and commercially-successful wireless products.
While the software architecture of the nRF91 Series is under wraps for
now, Nordic’s strategy remains to mask the inherent complexity of RF engineering while making it as simple as possible to code and debug wireless applications. That will make cellular technology accessible to all and encourages developers with little experience of wireless to explore its advantages and unleash their creativity to come up with new products.
Such a strategy has seen Nordic Bluetooth LE technology spread around the globe. The nRF91 Series SiP promises to do the same by bringing cellular technology to everything beyond the smartphone.