“The Internet will disappear. There will be so many IP addresses, so many devices, sensors, things that you are wearing, things that you are interacting with, that you won’t even sense it. It will be part of your presence all the time. Imagine you walk into a room, and the room is dynamic. And with your permission and all of that, you are interacting with the things going on in the room.” –Eric Schmidt, former CEO of Google
The demand for LTE-based Internet of Things (IoT) connectivity continues to gain momentum alongside the increasing need for connected equipment. According to Ericsson (2018) there will be more than 3.5 billion cellular IoT devices in market by 2023, making cellular technology a major communication enabler of IoT.
There are a number of competing technologies on the market to connect IoT devices. Many of the wide-area technologies, such as Sigfox, Weightless, and LoRa, are not LTE based. That is an important distinction because LTE-based IoT can be overlaid on existing LTE networks as a software upgrade. It is therefore much easier—and less costly—for the cellular operators to deploy.
The Advantages of LTE-based IoT
LTE-based IoT (LTE Cat-M and NB-IoT) devices offer a number of advantages over standard 3G and 4G devices: extended battery life, lower cost, and better coverage. Device battery life is extended when the improved signal environment allows devices to transmit at a substantially lower output power. The total cost of wireless is improved when the solution leverages an existing carrirer network; rather than creating one with your IT department. This is not to say Cellular IoT is the most economincal for every deployment, but certain types. To explain the better coverage via cellular IoT, there are two basic elements to look at:
Link Budget: Better coverage is delivered primarily because of a substantially better link budget, which is an important measure for power calculation. Link budget calculates the power received at the receiver (device) and accounts for gains and losses along the way. It is used to indicate how weak the signal can be from the tower to the device (and vice versa) for the system to still operate (communicate).
Larger Coverage Capability: Standards bodies have worked to ensure a better link budget for cellular IoT. It is about 20 dB (~ -164 dB) better than standard 3G and 4G technologies (~ -144 dB), ensuring coverage to an area approximately 7x larger (in an open environment). This 20 dB link budget improvement also results in better in-building signal penetration.
However, in spite of the improved link budgets and wider coverage areas, LTE-based IoT devices are still subject to the same in-building cellular signal penetration and coverage challenges experienced by any mobile phone user inside the building. A 2017 Zinwave study showed that 74% of workers have “frequent” or “sometimes” bad cellular coverage.
While operators continue to struggle to provide good in-building coverage from outdoor towers, a business cannot afford to have its mission-critical business functions inoperable “frequently” or “sometimes” because of a poor cellular connection. The impact on non mission-critical operations could also reduce the overall productivity of a company. To take advantage of the benefits of LTE-based IoT, there should be good and reliable cellular coverage throughout a building.
In-Building Cellular Coverage Options for IoT
There are three ways to deliver coverage indoors to provide the necessary quality of service for IoT: wired to router, wireless mesh, and dedicated cellular signal amplification.
Wired to Router Network
For many applications, this very simple solution will suffice. If the on-premise IoT solution is simply making use of a wide area, wireless-enabled router or gateway in which the on-site sensors and nodes are connected via wires, then an antenna can be run to the exterior of the building. To provide coverage to a single fixed point, this is a workable option.
However, for the antenna to pick up signal, there must be some service available to the exterior of the building. There are also some limitations around equipment placement—the antenna run cannot be too long due to the attenuation of the signal over the length of the coax cable.
Wireless Mesh Network
Some IoT networking technologies implement a form of mesh capability, allowing for a ‘string of pearls’ style approach to coverage. In this model, each network node becomes both a sensor and a gateway for other devices.
Some applications can leverage this capability quite well. 802.15.4 (Zigbee) is one such networking technology that makes use of mesh capability. However, there are two main weaknesses with this approach in extending the IoT network and coverage.
First, because each node becomes a full-time participant in the communications path, they need power all the time. This makes a mesh network very difficult to maintain when relying on battery power. Battery life for a node can decrease from 10 years to only a few months, depending on where it sits in the network and how often it’s used. Keep in mind that if a single node goes down in the network chain, all of the nodes after it are incommunicado. This is mostly a non-issue where nodes are powered, as with most smart home applications, for example.
The second issue is latency. Each node introduces latency into the network architecture, which can impact message time out and cause problems with real-time applications.
Dedicated Cellular Signal Amplification
Ideally, for IoT implementations, the technology used to amplify the signal simply relays the external coverage internally with delays that are so minimal that it is invisible to the cellular network. For mission-critical business solutions that rely on real-time communications, this is important. Introduction of noise into the system will also negatively impact a network’s performance.
Nextivity developed proprietary processors used in their line of Cel-Fi signal amplification systems to address noise and latency concerns. Cel-Fi smart signal boosters and active DAS hybrid products offer a network-safe guarantee and are approved by the Federal Communications Commission to boost signal up to 100dB, 1,000 times greater than allowed with wideband BDA repeaters.
Unlike mesh networks, these dedicated cellular signal amplification systems don’t do any other work so they can operate when needed, waking only when prompted or on a timer.
Cel-Fi: Enabling Cellular IoT
As the market expands, costs are plummeting, for both equipment and service, and the ease of installation makes these systems a desirable solution for IoT applications in a myriad of industries and applications, such as: construction sites, solar farms, vending machines, oil and gas remote sites, law enforcement, and public safety.
Download case studies to learn more about how Cel-Fi is enabling IoT connectivity for a wide variety of applications.
About the Author
Joe Schmelzer is Senior Director of Products at Nextivity. He has developed a variety of products and industrial devices for chipset vendors, OEMs, and operators, including products for Qualcomm, Google, Verizon, AT&T, FirstNet, and T-Mobile. He was also a founding member of CTIA’s Wireless Internet Caucus.