An overview of IoT connectivity with definition, key technologies and a comparison of the main technologies.
IoT connectivity is the means by which an IoT device, which can be anything from a simple sensor in a factory to a self-driving vehicle and encompasses applications from streetlights to robots, connects to the cloud, other devices and integration points such as IoT gateways. IoT connectivity is essential because it enables the I of IoT, without it, devices are just things. It is the IoT connectivity that brings value from IoT by communicating their data to enable action to be taken, services to be delivered and revenue generated.
Traditional cellular technologies’ strengths lie in data rate (mostly 4G, 5G) and range with complex designs optimized for mass consumer voice and data service; short range technologies like Bluetooth Low Energy (BLE) and ZigBee focus on data rate and battery life at the expense of connection range; LPWA technologies such as NB-IoT, provide superior battery life and coverage, but low data rate on the downside.
The three main technical requirements for any enterprise looking into IoT connectivity technology are coverage, energy efficiency and data rate. No single technology can excel in all these aspects, as these are trade-offs every radio technology faces. In addition, organizations should consider where their IoT offerings will be provided. If you need global IoT connectivity you should adopt a connectivity technology that is available worldwide.
All IoT applications need good coverage to connect devices, but some need to cover only certain indoor areas while others require extensive coverage in rural or remote regions. A technology with long range is better suited to connect devices scattered in a wide area.
Traditional cellular technology, such as 3G or 4G are a typical example of a wide area solution with excellent outdoor device radio range in most urban areas. LPWA technologies further improve the connectivity range by employing more robust coding schemes, which makes them ideal for reaching remote areas and penetrating deep indoors. Short range technologies, such as Wi-Fi and ZigBee, are suitable for connecting many devices deployed in close vicinity.
The energy efficiency of a connectivity technology has a significant impact on the lifetime or the maintenance cycle of IoT devices relying on battery or energy harvesting and is dependent on range, topology, and complexity of the connectivity technology. The overall energy consumption of the device also depends on the usage of the application, such as the frequency and duration of message transmission.
Short range technologies like ZigBee rely on mesh topology to forward messages from one device to another over multiple hops. That way ZigBee can extend its coverage but may deplete batteries more quickly as an individual device must constantly listen and be ready to relay messages. Wide area technologies, such as 2G, rely instead on star topology and keep most of the intelligence and complexity at the base station where power supply is not a limiting factor. LPWA technologies, such as NB-IoT, further reduce the energy consumption by stripping down the signalling protocol and reducing the amount of overhead to the bare minimum, thus enabling longer battery life (up to 10 years).
Data rate requirements for IoT applications vary from hundreds of bit per second (bps) for metering to several megabits per second (Mbps) for video surveillance on the uplink. Furthermore, with the advent of more sophisticated IoT applications, end devices need to be able to receive data packages with sufficiently high speeds, i.e., have high enough downlink capabilities.
Wi-Fi and traditional cellular networks such as LTE have used large bandwidth and complex waveforms with adaptive modulation rate to support high data rate. But they either consume more power or have a shorter range. In contrast, most LPWA technologies, for example NB-IoT and LTE-M, have lower data rate and lower energy consumption as they employ a more robust modulation scheme and run on commodity-priced micro-controllers with limited bandwidth.
As illustrated, traditional cellular technologies’ strengths lie in data rate (mostly 4G, 5G) and range with complex designs optimised for mass consumer voice and data service. Short range technologies like Bluetooth Low Energy (BLE) and ZigBee focus on data rate and battery life at the expense of connection range; LPWA technologies such as NB-IoT, provide superior battery life and coverage, but low data rate on the downside.
In addition to the main technical considerations discussed above, there are other technical features that can be highly relevant for certain applications.
The more devices are connected, the more important it becomes for a connectivity technology to be able to handle large numbers of connections within a certain area. The challenge is to deliver reliable connectivity while minimising interference between the various signals. Typically, device density within the massive IoT context is considered in number of devices per square kilometre.
The fragmented nature of IoT deployments mean there are a large number of IoT connectivity standards for organizations to choose from. How to connect to IoT is one of the most important decisions when it comes to IoT. IoT connectivity should be selected based on careful assessment of each deployment’s characteristics. For some very high speed, ultra-low latency connectivity is required. This may lead to adoption of 5G or 4G cellular IoT connectivity but this decision must be balanced against the likely cost and the power usage these technologies require. For some simpler deployments, low speed connections that are not always on can be ideal, requiring smaller batteries and delivering IoT connectivity cost effectively.
Selecting the most suitable connectivity technology is one of the strategic decisions that enterprises need to make when deploying IoT solutions. This decision can impact the success of the service as a poor choice can result in inferior performance or higher cost in the short term and hinder scalability and future-proofness in the long term.
Every use case has specific needs, which translate into certain technology requirements that determine the choice of most suitable connectivity technology. These technology requirements can be grouped into three categories – technical, commercial and ecosystem related.
While there is no single technology that can excel in serving all use cases, several of the technologies have gained prominence in terms of technology maturity, ecosystem support and scale of commercial availability. For IoT deployments in wide areas or remote locations, LoRaWan, NB-IoT, LTE-M or LTE Cat 1 are good complements that address the needs of most use cases.
The various IoT technologies exhibit different strengths and weaknesses, depending on the technical, commercial and ecosystem angle. This comparison from the report “Connectivity Technologies for IoT” illustrates the strengths and weaknesses of the major technologies.