Bench Talk

The cellular industry is taking steps to ensure that wireless carriers, rather than Low-Power Wide Area Network (LPWAN) providers, will secure the bulk of the revenue from long-range Internet of Things (IoT) connectivity solutions. The potential rewards are enormous, as even the least optimistic analysts project that there will be at least 20 billion IoT devices in service by 2020 and far more than that once autonomous vehicles hit the streets.

The cellular industry has a solid strategy for making its technologies better suited for IoT, including goals and a roadmap for using three key technology areas, as discussed in this excerpt from “The Cellular Industry Crafts Its Plans for IoT Connectivity,” available in the Digi XBee^® Wireless Modules eBook on Digi’s supplier page on Mouser.com.

Cellular Goals

The overall goals of the industry are shown in Table 1. From a technical perspective, the approach is the near opposite of what is being developed for its traditional voice and data markets. That is, the next major benchmark for the industry is its fifth generation, 5G, network, which promises blazingly fast data rates, delivered in part through channel bandwidths that are wider than they are today.

Table 1: Cellular Industry IoT Goals

In contrast, its plans for IoT are moving in the opposite direction, from the current wideband, high-data-rate capabilities of LTE-Advanced and LTE-Advanced Pro, to extremely narrowband, low-data-rate, low-power LTE variants such as LTE-M and Narrowband-IoT (NB-IoT). There are similarities among these paths, as each approach aims to reduce latency, increase spectral efficiency, and dramatically simplify and reduce network and end-user hardware costs. Nevertheless, providing IoT connectivity is very different from anything the industry has faced before.

The overall strategy is to implement IoT connectivity today using the latest versions of LTE, while consistently improving these versions within the next three to four years, at which time the standards making up 5G will have been released. The industry can then use the technological wizardry within the 5G standards to further increase performance. This becomes obvious when viewing Table 2, which shows the variations of the 3GPP standards Release 8 to Release 13, which were finalized in 2016. Note that LoRa^®, one of the most significant competitors to cellular IoT solutions being deployed today, already uses very narrow bandwidths and low data rates, which is a marketable benefit for LPWAN providers using this technology.

Table 2: Bandwidth and data rates compared

Cellular Technologies for IoT

The cellular road map is based on the use of three versions of wireless technology:

LTE-M

LTE-M is a low-power standard that supports IoT, by reducing device (modem) complexity and increasing coverage while allowing for reuse of the existing LTE infrastructure, enabling IoT devices to operate for at least 10 years in a wider range of applications. It is supported by major mobile equipment, chipset, and module manufacturers, and it benefits from current network security capabilities such as identity confidentiality and authentication, data integrity, and mobile equipment identification. It is currently being deployed by major carriers, such as AT&T and Verizon.

LTE-M is energy efficient, as it uses techniques called extended Discon­tinuous Repetition (eDRX) and Power Saving Mode (PSM). eDRX allows a device to have longer sleep cycles, so they can communicate with the network at different times: ranging from 10 seconds to 40 minutes or more. PSM improves IoT device battery life by providing advanced power management, turning the device’s modem on and off at scheduled intervals to save power while also allowing the modem to remain “connectable” even when most of its functions are inactive.

EC-GSM-IoT

EC-GSM-IoT is designed to provide coverage for IoT devices in difficult radio environments and is backwards-compatible with previous releases so it can be used within existing GSM networks as a software upgrade. It provides broad coverage, allows resource sharing between EC-GSM-IoT and legacy packet-switched services, and can be introduced into a network without dedicated resources for IoT. In addition to excellent coverage, EC-GSM-IoT uses a simplified protocol layer to reduce device complexity, extend battery life, and utilize a security framework comparable to 4G standards.

NB-IoT

NB-IoT uses the LTE physical layer and higher protocol layers and extends coverage and capacity while dramatically reducing device complexity. Designed to operate at almost any frequency range with existing cellular networks, NB-IoT focuses on transmission and reception of small amounts of data. It has the least power consumption of any cellular IoT standard while still providing long-range coverage, especially in “RF-resistant” environments such as buildings and below-ground installations such as subways.

Conclusion

The cellular industry wants to secure the bulk of revenue from long-range IoT connectivity solutions. The industry’s goals are many, including low-power consumption, enhanced and increased coverage, enhanced security, and scalability, among others. Three versions of wireless technology make up the road map to meeting these goals: LTE-M, EC-GSM-IoT, and NB-IoT. Read the complete article, “The Cellular Industry Crafts Its Plans for IoT Connectivity,” available in the Digi XBee^® Wireless Modules eBook on Digi’s supplier page on Mouser.com.