Training, Certification & Career

Hi guys,

According to Aruba's best practices, when planning a wireless network, think of about three devices per user. I have also seen that recommendation in many documents, webinars and the like. But unless you have three hands, you hardly will use the three devices simultaneously. At most you will use two, and most of the time you will use one device at the same time, as most people will do. Then, what's the reason of designing for three devices per user?

Regards,
Julián

The "take rate" is what percentage of users would even use the wireless.  That is a much more accurate way of planning.   I have not ever seen  that Aruba recommends that you plan for 3 times the number of users that will be in a space.  Please link to that document if it exists.

Hi,

 

This is an excerpt of the Aruba Certified Design Professional Official Certification Study Guide:

Regards,

Julián

Hi,

 

And this is an excerpt from the Indoor 802.11n Site Survey and Planning VRD:

What is marked in yellow is what I mean.

 

Regards,

Julián

 

I would highly recommend you take a read of the Very High Density 802.11ac Networks Validated Reference Design Guide. I don't recommend this because I think 3 devices per user = very high density but more because the theory and explanations in the the VRD are very well laid out and a lot of it can be extended to design in smaller environments.

 

If you can grasp the concept of duty cycle you will be better placed to deal with the 3 devices per user concept in design. A user may have 3 devices that all associate simaltaneously (I sit here typing on my laptop, with my phone in my pocket and my smart watch on my wrist - all are connected but I'm only actively using one) but the duty cycle of each device will vary.

 

On page 27 of the Engineering Configuration Guide (one of the many documents that make up the VHD VRD) there is a table showing the rationale column which assumes duty cycle in differing environments. Then on page 30 onwards there is some great detail around device duty cycle.

 

It's a lot to read but I believe you will be a better Wi-Fi Designer if you can work your way through it.

Hi Matt,

 

Thanks for your reply and your references. The concept of "duty cycle" is new to me, and it seems to be related directly on how many devices are active transmitting at the same time.

 

Another interesting concept is what Colin mentioned:

 

The "take rate" is what percentage of users would even use the wireless. That is a much more accurate way of planning.

 

Is there any table which shows "take rate" values for different environments (office, classrooms, airports, etc.)? There isn't in the VRD, and this table will be valuable since it is useful to determine the number of APs needed.

For example, my customer's environment is an open office with many users, and every user has three devices, but if I ask my customer for the "take rate", I am sure he will answer " I don't know".

 

Regards,

Julián

 

The take rate is an interesting variable as it could change from day to day and in an environment like a stadium (for example) it would change wildly depending on the event on at the time. The "I don't know" response is common and would be similar for concepts like duty cycle, client capability and applications.

 

However, I would make the assumption that the take rate for an typical Office environment would be 100%. If all users have laptops then a 100% design would be appropriate for a Mobile First workplace. Then you need to look at devices per user and the estimated duty cycle of each.

 

It's fun stuff when you start looking at it in depth this way. Keep up the good design.

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