IWLAN – enabling mobile applications like AGVs (iPCF)
For those of you who are following up my little blog series I am now happy to share a blog post about mobile applications with you. It gives you insights in why we are even caring about mobile applications. You’ll get also an idea which preconditions are available in Wireless LAN based systems. Finally, I’ll explain the specialties for Industrial Wireless LAN – where a timeout based mechanism is best and where clever scanning is key to your reliable application.
What’s mobility? First you might think about cars, trains and planes. There is just one thing common with wireless mobility: You do have different types of them.
At the end all of them boils down to: Is the client device moving and is it communicating while moving?
Suppose a client is not moving at all and needs connectivity, then you will find that trailing a cable is the most common solution in various industries. The cable enables better reaction times and higher throughput compared to a wireless technology. Nevertheless, as soon as you have a rotating application e.g. like in a wind power plant, you still might want to use a wireless link instead of a special cable because of wear and tear.
In industries the respective use case might be a modular part of an automation line which gets attached to the network by a wireless link. At a certain point this will get rebuilt in a different location within the plant to do it’s task at the new position.
Speaking about mobility I think everyone first has “moving and communicating” in mind. Imagine some folk with smartphone in hand attending a meeting about some app, but meanwhile changing locations. This person needs to get fast roaming/handover from one Access Point to another Access Point. This use case just rose with the advent of smartphones; in industries those mobile applications are in focus even longer. A classic example is an overhead monorail where a car body gets finalized through different process steps. One specialty here: you know beforehand which way the car body is going to take.
Standard wireless LAN
The performance also in roaming depends heavily on the used clients. Just like a crowded crossroad there might be a traffic which results in higher response times for the application. This happens because the clients are free to make their decisions.
Performance for mobility use cases with iPCF and iPCF-MC
So sometimes you just need some police officers doing the job right from polling (see my last post) up to providing the right information for all people at hand.
How does it work from a technical point of view? With iPCF-MC you get a management channel where all APs are delivering the information where the data channel is.
A client in search for a new AP just scans one channel for a short time and independent of the number of used channels he is able to determine the channel where to communicate the best.
With iPCF the client is already educated. As reliable maximum response times are crucial for automation applications he decides for roaming based on timeout criteria.
By the way: If you are just learning about it, we do offer very smooth in detail trainings about all of the above.
So what’s in it for me?
With standard wireless LAN we are speaking about roaming times in the 100ms range. In worst case scenarios like a client who is not reacting like he was expected to, with RADIUS authentication adding some extra time to think, … you might even have spikes in the seconds-area.
iPCF enables you to roam at roughly 50ms, dependent on the number of channels; iPCF-MC even without minding the number of used channels.
Speaking in a less technical manner: High performance roaming is only possible with adjusted WLAN, which is called iPCF at e.g. RCoax and iPCF MC in free-moving applications.
More to come …
Thanks for going through this article. I hope you enjoyed the glimpse of how mobility gets enabled and maybe you are teased to dig a bit deeper into that topic.
Within my small blog series there is more to come, and we will get back to the basics with the next one in the sequence:
- IWLAN – Related to interference (WLAN)
- IWLAN – Building block for IIoT (WLAN)
- IWLAN – Raising the standards (WLAN and iPCF)
As always: Feel free to give feedback, ask questions and approach me directly!