Finding the best wireless option for your IoT design
The Internet of Things (IoT) relies on a facile communications framework able to move data easily between embedded "things" and systems located at higher levels of the IoT hierarchy. For designers, a diverse set of wireless connectivity options provides the glue that holds IoT together. Selecting the best wireless option for an IoT device, however, requires a careful look at the bigger picture:
- The overall application,
- The required performance,
- The eventual physical location of the embedded devices.
Designers do not lack options for wireless connectivity and ICs able to support them. While ANT, Bluetooth®, WiFi and ZigBee may number among the more familiar alternatives, viable wireless connectivity solutions have coalesced around standards including 6LoWPAN, DASH6, EnOcean, Insteon and Z-Wave, among many others. At the same time, many successful designs build on proprietary RF approaches, while remote and highly mobile applications may have no alternative beyond cellular broadband.
Fig. 1: Within its highly complex structure, the IoT ultimately depends on wireless connectivity with the billions of mobile devices expected to extend to its outermost reaches. (Source: NXP Semiconductor)
Matching the target market
Despite the sometimes bewildering list of options, designers find that the best option for a particular IoT device design is often defined based on applications, performance requirements and environmental limitations. The need for compatibility in established markets often determines the best connectivity choice.
For instance, WiFi has emerged as a universal option, and requirement, for most applications. Often, devices targeting specific market segments need to support a specialized wireless connectivity option. Market momentum has pushed ANT to the forefront for fitness applications, while ZigBee dominates in applications related to the smart grid, building automation and home automation. Conversely, the large established base of compatible smartphones has pulled Bluetooth and Bluetooth Low Energy (BLE) into IoT devices targeting Personal Area Network (PAN) applications. Engineers can find a diverse set of related hardware solutions including modules and ICs for ANT connectivity from vendors including Nordic Semiconductor, Panasonic and Texas Instruments; ZigBee solutions from Atmel, NXP and Microchip; and Bluetooth/BLE solutions from CSR, RFM and STMicroelectronics.
In many cases, connectivity options are further defined in higher-level standards such as DALI for intelligent lighting systems, Modbus for industrial systems, and ISO/IEEE 11073 for medical device connectivity. Absent market compatibility concerns, the choice often becomes driven by performance requirements including:
- Operating range,
- Ability to coexist in environments with multiple competing wireless protocols.
Balancing range and data rate
In location-sensitive designs, engineers turn to sub-GHz frequency options, which provide longer-range operation at a similar radio power level compared to higher-frequency solutions. Lower-frequency signals can also achieve better penetration through obstructions such as walls.
In contrast, 2.4 GHz communications can support higher data rates and better coexistence. Although most IoT devices will likely not need the high data rates available with higher frequency communications, they will probably face a complex radio environment that dictates a need to coexist with different devices and communications methods. In these cases, 2.4 GHz options become more important for their ability to support interference-resisting communications protocols using spread spectrum and frequency hopping.
Fortunately, engineers need not rely strictly on theory to explore the best alternatives for IoT designs. Development kits such as the Texas Instruments Tiva C Series TM4C1294 Connected LaunchPad (EK-TM4C1294XL) enable engineers to explore multiple concurrent connectivity options in designs using several TI BoosterPacks for WiFi, ZigBee, sub-GHz and 2.4 GHz proprietary devices, among others. Besides development kits based on TI processors, engineers can find similar IoT-specific development kits such as the Avnet Wi-Go kit based on the NXP Freedom Development platform powered by the Kinetis K, the Intel Quark-based Galileo board, and diverse processor-specific development boards from Keil.
As described in the webinar "Turning the Cloud into a Rainmaker!," building profitable IoT applications requires the right combination of hardware, cloud services and application expertise. The webinar, taught by technical experts from TI, Avnet and Exosite, is available on demand. With the broad range of available connectivity options and supporting services, designers can be confident they will find the optimum solution for their specific IoT design.