Accuracy. Choosing an indoor positioning technology

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This post is part of the “Choosing an indoor positioning technology” series. The series aims to help anybody evaluating and buying Indoor Positioning Systems (IPS) to ask the right questions and make better informed decisions. This post focuses on Accuracy. If you are only after the core message and evaluation criteria, you can skip ahead and simply focus on the bolded text.

Series Background

Choosing an Indoor Positioning System for use cases such as indoor wayfinding is often a daunting task. Complex technologies, foreign terminology and a large pool of vendors with varying value propositions can easily overwhelm anyone. Most companies will pitch you their solution or compare different technologies and their respective advantages and disadvantages. However, the truth is that the fit of an indoor positioning technology depends upon the use case you want to solve. Therefore, instead of pitching our solution and contrasting its performance to others, we thought we will give you a tool to evaluate different technologies for your intended use case. 

More specifically, we will present to you a range of suboptimal questions we see many customers ask and explain why they are suboptimal. Then we will present to you a set of questions we believe are more appropriate given prior explanations. These questions you should ask yourself and/or the vendor you are evaluating, in order to make a better decision on the solution you need. 

The wrong questions to ask about Accuracy 

There is one reason why indoor positioning solutions exist: outdoor positioning systems (GPS) lack accuracy indoors. Hence, the first and foremost criteria for customers is often the accuracy of the indoor positioning technology. Based on various conversations we had with customers, as well as the 20+ years of experience from our parent company Sonitor, we see two different types of customers (let’s call them Type 1 & Type 2):

  1. Type 1 asks: What is the highest possible accuracy I can get? 
  2. Type 2 asks the opposite question: What is the minimum accuracy I need?  

The problem with Type 1 customers is that they lose track of their use case and get ‘accuracy greedy’. They tend to overspend (higher accuracy usually comes at higher cost) which in the long run results in poor utilisation of budgets and eventually, churn. 

The problem with Type 2 customers is that they only care about the technical viability of a use case and are too cost conscious. These customers tend to purchase a solution that solves the use case at its bare minimum, but does not result in a good user experience. This leads to low adoption and usage of the technology and eventually churn. 

The right questions to ask about Accuracy 

Instead of asking about the upper limits of the technology or the lower limits of the use case, customers should focus more on the intended use case and customer experience. This will increase adoption of the use case and hence, long term success. Therefore, to counteract the problems that Type 1 and Type 2 customers run into, here are some questions you should ask yourself and/or the vendor during the technology evaluation phase: 

  1. What kind of accuracy do I need for my use case?
    There are three different types of accuracy: 0D, 2D and 3D. 0D can tell you if a person is in a room/zone or not (binary). 2D enables you to understand where a person is in a room (X & Y coordinates). 3D allows you to not only see where a person is in the room, but also the height at which he is holding his smartphone/positioning device (X, Y & Z coordinates).
  2. What accuracy do I need to for my use case? 
    Room/zone accuracy is binary, either somebody is in the zone or not. 2D and 3D accuracy have a continuous scale, measured in centimeter or meter.
  3. What accuracy do I need to achieve a good user experience for my use case?  
  4. Looking into the future, what are the next use cases I might want to develop? What is the accuracy I need for those use cases and a good user experience?  
  5. Can technology/vendor X deliver on my needs based on questions 1 through 4?  

practical example 

To exemplify this let’s think of the basic navigation use case. GPS has an approximate accuracy of 4.9 meters. While this is not very accurate, it is sufficient for a good user experience outdoors since the objects we navigate to tend to be big (e.g. parks, buildings, etc.). Now if we apply the same accuracy indoors, this will lead to a poor user experience since we navigate to much smaller objects. For example, in a grocery store 5 meters can span 2 to 3 isles. Now, a grocery store manager might say that he wants user to navigate to product classes. Having 5 meter accuracy might get you to the right product category in some cases (when you land on the right side of the isle) and to the wrong product category in others (e.g. opposite side of the isle). Poor customer experience would result in customer frustration and low adoption rate over time. In addition, if thinking about more advanced use cases, e.g. navigate directly to individual products, 5m will be too inaccurate.  Eventually, the overall failure of the use case would lead to stakeholders blaming the technology and terminating the project. 

In summary, asking the right questions about the accuracy of an indoor positioning technology will set you up for a successful use case deployment. Walking through the accuracy needed for the intended use case, requirements for a good customer experience and more advanced use cases in the future will help to pick a technology & vendor that can deliver on your expectations without paying more than necessary.


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