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Argument Against Using iPad for WiFi Surveys

Argument Against Using iPad for WiFi Surveys

I came across a CWNP forum post with comment below arguing against using iPads as a WiFi survey platform. Regular readers of this blog and followers of @WLANBook know that we think using iPads for WiFi Surveys is a good idea. We like the concept so much that we have created an “app for that“.

I agree that the iPad isn’t the perfect platform for WiFi Surveys but I disagree 100% that it is a bad idea. My counter arguments are after comment below.

I was thinking about site surveys using an iPad, too, but after some research and discussion with a couple of software vendors, I came to conclusion that this was a bad idea. There are many reasons why you can’t use an iPad (or a droid tablet, for that matter) for a quality site survey. The most important reasons are:

(a) iPads and most of other tablets have a scaled-down Wi-Fi chip. If you perform active surveys, no matter how good your AP is (e.g. 450 Mbps), your measured throughput rate will be too low.

(b) Site survey software typically extrapolates data and performs some other CPU-intensive operations. iPads don’t have sufficient computing power for that within a reasonable amount of time.

(c) iOS and Android does not allow developers to capture raw frames. This makes it impossible to gather vital information necessary for a quality site survey. To give you just one example, if you can’t capture raw frames, you cannot detect multi-SSID APs; the application will “think” that it is dealing with several different physical APs located very close to each other, all of them using the same channel. As a result, it will show a totally wild interference picture.

There are other less important reasons. E.g., it’s difficult to mark your location on the floor plan with a finger.

The bottom line is that while iPad is an attractive platform, one can’t use it for each and every task, unfortunately. There are things that require a traditional OS with a fast Intel CPU. I’d go for a light Intel i5 or i7 notebook or tablet, Windows 7, and a good site survey tool (Ekahau, TamoSoft, AirMagnet).

Using iPad for WiFi Surveys is Good Idea

I was thinking about site surveys using an iPad, too, but after some research and discussion with a couple of software vendors, I came to conclusion that this was a bad idea. There are many reasons why you can’t use an iPad (or a droid tablet, for that matter) for a quality site survey.

There isn’t a universal definition of a “quality site survey” but if a post WiFi survey report includes below then survey was was pretty good.

– Desired RSSI coverage map
– Desired S/N** ratio
– Throughput tests if doing active survey

Our iPad app can provide above and the results be closer to what the end user will experience because the actual device they will be using was used for surveying. **Noise value from radio card is not possible with current iOS API but can be estimated.

(a) iPads and most of other tablets have a scaled-down Wi-Fi chip. If you perform active surveys, no matter how good your AP is (e.g. 450 Mbps), your measured throughput rate will be too low.

True, hardware is different / smaller than some laptops but expecting to get 450 Mbps or even 300 Mbps from any device (including laptops) is not realistic. Most of the data rates on vendor boxes for 802.11n are marketing hype actual results are much lower. Check out post at WLANPros.com about iPad 1 and 802.11n.

(b) Site survey software typically extrapolates data and performs some other CPU-intensive operations. iPads don’t have sufficient computing power for that within a reasonable amount of time.

I don’t have any real world benchmarks (either) but based on field tests the iPad2 is very usable for all tasks including heatmap generation.

(c) iOS and Android does not allow developers to capture raw frames. This makes it impossible to gather vital information necessary for a quality site survey. To give you just one example, if you can’t capture raw frames, you cannot detect multi-SSID APs; the application will “think” that it is dealing with several different physical APs located very close to each other, all of them using the same channel. As a result, it will show a totally wild interference picture.

True iOS wireless APIs dont’ allow access to raw frames. If there was enough demand for this type of app I guarantee someone could create a custom driver for iOS that would get raw frames from wireless card. Not sure if I agree with multi-SSID AP issue mentioned above. The app should be able to correctly account for this scenario since most modern APs use virtual APs with different Mac addresses per SSID. Also most survey access points are configured with single SSID per frequency.

There are other less important reasons. E.g., it’s difficult to mark your location on the floor plan with a finger.

Use stylus, also zooming in/out on iPad is pretty easy.

The bottom line is that while iPad is an attractive platform, one can’t use it for each and every task, unfortunately. There are things that require a traditional OS with a fast Intel CPU. I’d go for a light Intel i5 or i7 notebook or tablet, Windows 7, and a good site survey tool (Ekahau, TamoSoft, AirMagnet).

iPad is solving issues that laptop based solutions can not.
— Battery never lasts long enough
— Too heavy
— Cost of laptop high relative to iPad
— Cost of software very high relative to typical iOS/iPad app.
— Survey with actual device/wireless card that will be used on network
— Perform throughput test with actual device/wireless card that will be used on network
— Need for external PC/USB card
— Need for external GPS sensor
— Rear facing camera to snap photo of physical site survey issues (closet, AP placement, etc)

It easy point out negatives only without including the positives of a tablet/iPad solution (or negatives of a laptop based solution).

80/20 Rule

iPad meets 80/20 rule.

iPad WiFI Survey easily has 20% of the core features needed and will get 80% of end results needed for a quality site survey.

Most poor quality site survey reports have nothing to do with software / hardware used but knowledge of operator.

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Filed under: WLAN Site Survey, WLAN Tools

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