Efficient Testing Techniques for Optimal RF Performance of IoT Products

July 15, 2019 Nirav Mistry, VOLANSYS Technologies

IoT solutions have application-specific dependability when they are exposed to varied environmental conditions. For example, a smart meter installed in the basement of an apartment complex must be able to withstand tough conditions. Expectations for reliability, performance, and long-time availability are therefore extremely high, and connectivity is a crucial success factor. Any failure in conveying information about the state of things in a reliable, timely, and energy-efficient manner may result in high cost, insufficient user satisfaction, and physical damage to people or things.

The complex architecture of IoT systems and their unique characteristics mandate various types of tests across all system components. Reliable communication is a must for any IoT product in noisy atmospheres as well.

RF Testing:

Communication range and latency are two major factors to measure performance of any IoT products. To make sure that the products meet the range and latency requirements, RF testing plays a very important role.

  1. Range Test - Device range testing under certain RF condition.

Several emerging IoT applications require coordinated, real-time analytics at the ’edge’ of a network, which can be achieved by using algorithms that require a scale of computation and data volume/velocity. However, the networks connecting these edge devices often fail to provide sufficient capability, bandwidth, and reliability. Thus, range testing is very essential for any IoT application.

Range Testing Scenario - LOS (Line of Sight) - Examine the module indoor and outdoor to determine the effects of the surrounding environment on the signal.

LOS Test:

  • Find out the maximum healthy communication range of two IoT devices
  • Both transmitter and receiver should be at same 5-meter height
  • Data communication should check both ends

 

LOS Test – Observational Possibilities

  • Strength of signal is in relation to distance over transmission medium
  • Reflection occurs when the signal hits a surface that is larger compared to the wavelength of the signal
  • Diffraction occurs when the signal is obstructed by a sharp edge
  • Received signal must have enough strength so that circuitry in the receiver can interpret the signal
  • Signal must maintain a level higher than noise to be received without error
  1. Performance & Latency Testing

Testing overall communication behaviour of IoT devices is important in all phases of the product life cycle to ensure proper functionality, long battery life, and high performance. The latency requirements ranging from minutes to microseconds become relevant to power consumption and battery life.

To perform latency testing, healthy communication range needs to be identified using LOS testing. Finding average response time (sending data from one device to another device for multiple times) will cover complex aspects like timing analysis, load testing, real-time stream analytics, and time-bound outputs, under the extremes of data volume, velocity, variety and veracity. There two types of latency measurement:

  • Forward latency
    When any coordinator device sends any command to the end device, the response time of the command is forward latency
  • Reverse latency
    When any end device (sensor device) sends the acknowledgment to the coordinator device, it is reverse latency

For Dynamic Environment: Unlike application testing performed in a defined environment, IoT has a very dynamic environment with millions of sensors and different devices in conjunction with intelligent software. Hence, finding required packets can be a challenge. At any point in time:      

  • Many devices could be transmitting separate data at the same time.
  • A single packet could be transmitted multiple times on a multi-hop route.

Real-Time Complexity: IoT applications can have multiple real-time scenarios and their use cases are extremely complex. Analysis of network formation involves validating the following:

  • Did the device join the network?
  • How and where did the device join the network?
  • Is the network routing acceptable?
  • Related subsystems and components owned by third-party units
  • Complex set of uses cases to create test cases and data
  • Hardware quality and accuracy
  • Interface in Environment
  • Security and Privacy

It is highly advisable to perform RF performance testing for all IoT devices to make sure that the products maintain high performance, even in noisy environments.

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Nirav is associated with VOLANSYS Technologies as a Quality Assurance Lead with over eight years of experience. He has worked on various domains like embedded and IoT. RF and performance testing are some of his key areas of expertise and he is experienced in leading manual and automation testing.

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