Trends in Cellular IoT Part1
How the LTE-MTC Standard is Influencing IoT Hardware Design
This article is the first in a series discussing the trends in cellular-based IoT.
Decades before the Internet of Things was envisioned (or the term even coined by entrepreneur Kevin Ashton in 1999), machine-to-machine (M2M) communication devices had been the means by which ATMs, remote monitoring equipment, and asset-tracking applications were connected to 2G GSM cellular networks. There are perhaps millions of M2M devices still operating in the field today on 2G, but cellular operators are gearing up to switch them over to Long Term Evolution (LTE) networks to increase capacity and make available needed spectrum for the anticipated explosion of LTE-based IoT devices.
As a long range wireless technology, LTE (also known as 4G LTE) has all the requirements necessary for IoT – an IP-based architecture with built-in security, good spectral efficiency, high throughput, and low latency. Yet, the current LTE standard wasn’t exactly written for huge wireless networks of low-complexity, energy-efficient IoT devices communicating with one another at low data rates and often with long gaps between transmissions.
The current generation of LTE devices also cost much more than traditional M2M devices, as well as most devices based upon other long-range technology standards. Moreover, since most M2M/IoT devices are battery-operated, they require a much higher level of energy efficiency than current LTE devices. Another important concern for LTE-based M2M/IoT devices is coverage. Since many devices will be installed underground or in basements – environments often with poor reception – they’ll need to be capable of deep coverage.
To address the challenges of cellular-based M2M/IoT devices, the standardization group 3rd Generation Partnership Project (3GPP), which is responsible for cellular telecommunications network standards, has developed a new version of the LTE standard which delineates a type of LTE-based device (i.e., Cat-M, Cat-0) designed to meet the needs of a wide range of M2M/IoT devices. Called LTE for Machine-Type Communication (LTE-MTC / LTE-M) by 3GPP, the new standard promises a new generation of devices with lower costs, deeper coverage, and better power consumption. These devices will also enable the rollout cloud services that not only process M2M/IoT data, but also provide a vehicle for developing value-added services that work well with current broadband services.
The LTE-MTC standard is already influencing the design of M2M/IoT devices through a combination of software and hardware design optimizations, which will simplify user equipment (UE) devices by reducing bandwidth, transmit-power, and support for downlink transmission modes. In addition, these optimizations will provide for ultra-long battery life via deep sleep modes as well as offer extended coverage.
Optimizing throughput requirements is a key element of the LTE-MTC standard. LTE devices today are designed to support high throughputs of more than 300Mbps for smart phones, tablets and other mobile devices. But the throughput needs of a smart phone are quite different from an M2M/IoT device used in fleet management and logistics applications, which typically need only several hundred Kbps for uplink transmissions. The new devices based upon the LTE-MTC standard will be capable of supporting data rates of only up to 1Mbps, allowing designers to utilize lower-performance chipsets, with slower clock frequencies and reduced processing requirements to achieve cost and power savings. In addition, the reduced bandwidth needs of LTE-MTC devices are also expected to help decrease device costs.
The architecture of M2M/IoT devices is another area where the LTE-MTC standard is influencing hardware design. LTE devices are typically based on ARM architecture and utilize two cores: one for the protocol stack and another for physical layer control software. By implementing a protocol stack that's integrated on a single core with physical layer control software, lower device costs can be realized by utilizing a less processing-intensive ARM Cortex® architecture.
But the new LTE-MTC standard is doing more than optimizing traditional LTE devices for M2M/IoT. Since other long-range M2M wireless technologies, such as LoRa and SigFox, are being implemented, the new LTE-MTC standard is ensuring that LTE can effectively compete against other long-range, wireless technology standards for broad marketplace adoption.
The second article of this series on the trends of cellular-based IoT will focus on other long-range wireless technology standards to more fully address how well they compete against LTE-based IoT.
Are you an engineer working on developing IoT solutions? We are interested in your opinion! Have your say on how the new developments in cellular IoT are changing your IoT designs.