Testing at the IoT Crossroads

December 17, 2019 Cheryl Ajluni, Director, Electronics Industrial System Group and Software Solutions, Keysight Technologies

The world we live in has changed. Horse and buggies have been replaced by the modern car. Landlines have given way to smartphones. And, analog devices have been supplanted by digital counterparts with an ever-increasing level of intelligence.

Today, these intelligent digital electronics form the foundation of the Internet of Things (IoTs) ecosystem, and their growth trajectory is exponential. Spurred on by the availability of inexpensive electronics and continual emergence of wireless technologies, IoT devices are reframing how we live, work, and play.

While the extent of the IoT’s full impact may still be under debate, it’s clear that these devices are at a crossroads as they transition from “nice to haves” to “must haves” that people will increasingly depend on for mission-critical, and sometimes, life-critical applications.

Enabling IoT devices and the IoT ecosystem to successfully make this transition will require designers to overcome several key challenges. 

Advancing the Mission-Critical IoT

Nowhere is the advance of the IoT into the mission-critical space more evident than in the healthcare sector. Here, manufacturers of medical equipment are producing a range of innovative connected devices, from surgical robots, dermally-implanted sensors, and tracking pills, to a variety of wearable devices like infusion pumps that collect and transmit key medical data. This so-called Internet of Medical Things (IoMT) is enabling a fundamental transformation of healthcare delivery, reducing costs while increasing clinician effectiveness and improving patient outcomes.

But that’s only the tip of the iceberg. The mission-critical IoT is also advancing into other key industrial sectors, such as connected cars and Industry 4.0.

Autonomous vehicles are one of the most high-profile applications benefitting from the IoT. In this application, sensors are used to detect and communicate with other vehicles, the road, highway infrastructure, and even pedestrians. In smart factories, the use of IoT is enabling the realization of Industry 4.0. It has meant the implementation of autonomous robotics and augmented reality on the factory floor. It has allowed machines, systems, and human operators to communicate and operate together on the assembly line, while also providing actionable insight for human operators.

But these advances come at the price of new, more stringent performance characteristics and requirements as defined by the industry in which the IoT will operate. A list of the most common requirements is summarized in Table 1. These characteristics make mission-critical IoT applications more demanding than consumer applications, and it forces players in the IoT ecosystem to address growing concerns over interoperability, security, and reliability.

Requirement
Description
Reliability
 
The ability to perform to specification in hostile environments, often for many years.
Precision
 
Assembly line and other applications require the repeated placing of components within very fine tolerances.
Real-time Performance
 
Many applications, particularly in factories and other industrial processes, require a real-time response to events.
Scalability
 
Modern sensor and other networks may contain tens of thousands of devices and must therefore scale appropriately.
Security
 
The proliferation of connected devices on a network can also represent a growth in points of vulnerability and unwanted access. Security must be designed into solutions to protect both end-point devices and networks.
Interoperability
 
Interoperability is a key requirement in large solutions that may integrate devices from multiple manufacturers, often from different regions.
Table 1. Typical performance characteristics and requirements for mission-critical IoT applications.

As with any emerging market, the solution to these concerns lies in appropriate regulation and definition of standards. However, because the IoT is still in its infancy, there is currently no single standard that governs IoT device operation in all applications. Instead, IoT standards are fragmented, with several organizations (e.g., ITU, ETSI, IEEE and IETF, and industry bodies such as oneM2M and GCF) working around the world to balance regulation with the needs of an innovative market.

Against this evolving regulatory landscape, device designers must continue to design their IoT devices and systems to comply with mission-critical requirements. Likewise, each component in the device or system needs to be designed to meet the specific challenges posed by its environment. Plus, it must be thoroughly tested for optimized performance and reliability using a comprehensive and transparent testing approach.

Understanding the Challenges Ahead

Within the IoT ecosystem, designers face challenges at three key levels:

IoT Device

IoT devices (sensor modules) are typically designed around a microcontroller unit with analog and digital interfaces, depending on the needs of the application. An RF transceiver interface is also required for communication with the outside world (Figure 1).

Figure 1. A block diagram of a typical IoT sensor module.

Within the device, size and power management are common challenges for designers, with many sensors having to operate for extended periods of time on battery power or using harvested energy. The RF interface is potentially a significant consumer of battery power. Low-power wireless protocols (e.g., LP-WAN) have been developed to provide a compromise between transmission range and power consumption. In some environments, such as smart factories, power consumption may be less of an issue than sensor density where multiple devices must communicate without interference. Here, signal integrity becomes a key priority. Additionally, in industrial environments where heavy machinery is commonplace, electromagnetic interference (EMI) compliance is essential.

By far, one of the biggest challenges at the IoT device level though, is battery life. Designing an IoT device with an optimized battery life requires an accurate power consumption profile and accurate characterization of the device’s dynamic load. Understanding the relationship between the load demands, the amount of current required, and for how long it’s needed is an important aspect of determining likely battery life.

The battery’s operating characteristics, whether a non-rechargeable coin cell or a rechargeable LiPo battery, also need to be understood and factored into a complex power management routine to prolong and optimize battery life. Being able to accuracy track the load on the battery, and what is demanding it, can help.

Designers can use this information to develop a robust power management process. The designer might determine, for example, that during operation, an IoT device’s current spans a very dynamic range, from hundreds of mA when the wireless transceiver initiates a link, down to sub uA when the transceiver is off, the microcontroller is in its most optimal sleep mode, and the sensor is not active. With such insight, the designer can then sequence high current consumption program functions so they do not occur at the same time (Figure 2).

Figure 2. Using the right tools to analyze battery drain in wireless IoT devices is essential to optimizing battery life. Keysight’s N6705B DC power analyzer and N6781A 2-quadrant source measurement unit are ideal examples of tools that can be used to characterize battery drain and provide insight into a device’s battery load over time.

Wireless Communications

Wireless communication is essential for IoT devices. To enable this communication, designers can choose from a wide range of protocols, such as Bluetooth, ZigBee, Z-Wave, Wi-Fi, NB-IoT, and many more, depending on the characteristics of the application. In mission-critical scenarios, IoT devices must perform in the presence of multiple users, with different wireless technologies, in the same spectrum. Verifying that a device can handle this load is critical to ensuring robust wireless connectivity.

In large buildings, such as hospitals, where dense device operation is a given, reliable wireless communication is mandatory. Here, medical equipment, patient monitoring devices, smart lighting, security systems, and even wearable devices carried in by visitors must operate simultaneously and unimpeded by interference from one another. This can be especially problematic in hospitals where medical monitoring devices share the 2.4 GHz ISM band with the likes of cordless phones, wireless video cameras, and microwave ovens. Making sure an IoT device’s operation can work as anticipated in this type of environment is crucial.

The Network

With the arrival of 5G, more and more applications will take advantage of the improved cellular network performance to “offload” computational workload to the data center, placing more importance on network security and stability. All manner of devices can be expected to connect to the network, some of which may, intentionally or otherwise, represent threats to network integrity and security. Network management tools and systems must, therefore, be developed to mitigate these issues and other such risks.

Conclusion

IoT capability is now being designed into ever more mission-critical applications across all industrial sectors. Success in this arena demands that designers follow a well thought out process to design, test, and validate their smart devices and systems. That process must involve test and measurement at the device, wireless communications, and network level.

Fortunately, designers now have access to a wide range of test options to help verify the functionality of the various layers in the IoT ecosystem (Table 2). However, conducting the right tests alone is not enough. To ensure an IoT device or system is built to survive and thrive in mission-critical applications, designers must choose the right tools for the right job, and those tools must be accurate, high performance, and flexible.

One of the key tools to consider is battery drain analysis, which helps designers accurately determine their device’s current use and the duration of each of its operating modes. Signal integrity and power integrity tools can be used to evaluate high-speed serial interconnect and analyze how effectively power is converted and delivered from the source to the load within a system. An accurate EMI simulation and modeling tool can help estimate emission levels before hardware is developed. And, to ensure an IoT device can communicate effectively, wireless connectivity and co-existence testing are essential.

Ecosystem Layer
Tools
Description
Device
Simulation & Design
  • Understand device operation/performance expectations
  • Determine performance/functionality trade-offs
Battery Drain Analysis
  • Measure device’s dynamic current range over time
  • Determine the optimal balance between functionality and battery life
Signal Integrity Test
  • Evaluate high-speed serial interconnect
  • Validate and correlate actual vs. simulated signal integrity
Power Integrity Test
  • Analyze power conversion and delivery from source to load via the power distribution network
Wireless Conformance Test
  • Verify design and pre-conformance to appropriate wireless standard
EMI Simulation and Modelling
  • Simulate radiated emissions and determine actual levels vs. standards
EMC Compliance
  • Ensure compliance with relevant EMC standards
Wireless
Wireless Connectivity Test
  • Test & troubleshoot receiver
  • Verify interoperation of wireless IoT standards
  • Verify that IoT devices can handle multiple standards
 
Coexistence Test
  • Ensure that IoT devices can function correctly in the presence of multiple users with different wireless technologies in the same spectrum
 
Network Simulation
  • Test real-world performance and compliance of IoT devices during integration, interoperability, and carrier acceptance testing
 
Network Readiness
  • Verify wireless coverage and network quality
Network & System
Network Performance Assessment & Monitoring
  • Verify, quantify, and troubleshoot network performance
 
Network Infrastructure Performance Test
  • Test peak network performance
 
Network Validation
  • Validate protocol compliance and interoperability
 
Applications & Network Security Test
  • Harden network and security performance by modeling security attacks/malware
  • Validate network, data-center, and service provider networks
Table 2. Test and measurement tools for the IoT ecosystem.

Without a doubt, there is a wealth of opportunities in the mission-critical IoT. Whether designers succeed or not will depend heavily on the choices they make and how they address the challenges that arise.

Making the right decisions up front, like picking the right design tools, can go a long way in helping designers outpace their competition.

Cheryl Ajluni is Director of the Electronics Industrial System Group and Software Solutions at Keysight Technologies.

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