No static at all

Posted on Tuesday, November 27, 2018

I saw an article last week saying that mobile networks were becoming faster than WiFi. That got me thinking about why smartphone users select WiFi instead of using their mobile operator.

The story appeared in the GSMA’s Mobile World Live with the title Mobile Starting to Dominate WiFi But US Still Lags. It quoted a study by wireless mapping company OpenSignal which said that mobile download speeds were faster than WiFi in both richer countries like France or Australia and in what the article called “less developed” places including Qatar, Turkey, Mexico and South Africa. The exceptions in developed countries were the US, Hong Kong and Singapore, where mobile “significantly underperforms” WiFi.

The full report can be found here. It says that mobile was superior to WiFi in 33 countries or 41% of the 80 countries studied. I am not sure I would have used the term ‘dominate’ since normally this is reserved for market shares over 50% even over 60%. Maybe ‘starting to dominate’ is OK but then we would need trend information and, while that is not displayed in the report, OpenSignal makes the qualitative case that the same study done in the past would not have been so positive for mobile. (The growth of smartphones and improved 4G coverage must have meant WiFi was superior in the past.)

With these kinds of studies, understanding the methodology is critical to interpreting the results. OpenSignal says it uses on-device measurements, so I assume the comparison data is the average speed when the smartphone was using mobile versus the average speed when the smartphone was using WiFi. That seems like a fair experiment although I think it shows more about when someone chooses to use WiFi versus using mobile. This is not a comparison like I am sitting in a Starbucks or in my living room and switching between WiFi and mobile to see which is better.

Interestingly, the study found that there was no correlation between WiFi performance and the time spent on WiFi. It would appear that we are not dropping into Starbucks because the coverage on the street is crap. “However, there is a correlation between higher per capita GDP and more time spent on Wifi.” Interestingly, OpenSignal attributes this to higher per capita GDP implying better WiFi infrastructure. But if that were the case, then there would have to be a correlation between time spent and quality, which statistically there was not.

This part of the analysis I believe they got wrong. And frankly, I don’t believe it. While I can agree that higher GDP per capita likely means better WiFi, I would have thought income correlates with negatively with time spent on WiFi because much WiFi usage is avoiding carrier charges. As a frequent flyer whose CFO is scandalized by my roaming bills, I try use WiFi as much as I can when traveling. I also use it for software updates and watching videos – heavy lifting tasks that might wipe out the megabytes included in my base subscription. I don’t necessarily care if WiFi is better; I care that it is cheaper.

And I have a data plan / subscription with a big bucket that I don’t think I have ever exceeded.

When I had an office with a dozen employees, I think I was the only one with a plan. Everyone had a smartphone but they used WiFi for data. While I might be careful about turning WiFi on and off – to preserve battery – they were careful about turning their mobile data on and off – to avoid spending money or using their allocation.

Let’s do some quick math:

  • MinTIC says there are 62.2M mobile subscribers in Colombia. Since there are only about 45M persons in the country – including small children, the very old and infirm, those in prisons and in rural areas without service – that means a penetration of 138%.
  • Smartphone penetration is not an official number but this source says 71% in Colombia in 2017. A year later it is probably higher so let’s say 75%. The source says the base is individuals over the age of 5. According to the DANE, Colombia’s statistical institute, that would be about 91%. So 45*.91*.75 = 30.7M, the estimated number of smartphones in the country.
  • MinTIC says that there were 24M mobile broadband users (including 14.1M prepaid users and 9.9M mobile broadband subscribers). Growth has been fairly slow, about 1% per quarter so let’s assume that today there are 25M mobile broadband users.
  • That means there are nearly 6M smartphone users (30.7-25) that neither have a mobile broadband subscription nor use prepaid. Either they never use their smartphone to access the Internet or they only use WiFi.

My suspicion is that the 14.1M prepaid users are heavy WiFi users as well.

OpenSignal noted that the programming in smartphones favors WiFi. If there is an open network or one in which the user has previously been authenticated, phones automatically go to WiFi and ignore the mobile connection, even if it has superior performance. The company thinks that its data should convince device manufacturers to do what it says high-end Samsung devices do and connect to both, using the path with the fastest speed.

The result would be a kind of automatic WiFi offload although the carriers could not charge for it.

That would seem to make sense regardless of whether the OpenSignal study favored mobile or WiFi but only if it were ‘costless’. My guess is that there would be a battery life impact at the very least. Personally, I should get an experience benefit from the arrangement because Colombia is one of the country’s in the OpenSignal list where both upload and download are better on mobile than WiFi. (Hardly surprising. At least in Bogotá, my experience is that restaurant and coffee-bar owners think it important to have WiFi but they could care less what the performance is. In fact, they likely take the skinniest DSL pipe they can buy to minimize their costs. The same economic imperative that makes Colombians have smartphones but only use WiFi means that the WiFi they get is lousy.)

But not everyone would want that. Six million Colombians would still turn cellular data off. Fourteen million prepaid smartphone users would still be selective about when they use mobile or Wifi to minimize their charges. And some proportion of the remaining ten million Colombian smartphone users with data plans would also be selective for some types of traffic to avoid blowing their bucket and paying steep overage charges (like me).

The economic argument can be more compelling than the technological.

The girls don’t seem to care what’s on / As long as it plays till dawn

Title Reference: From Steely Dan’s FM, a 1978 single, the title song from a forgotten movie of the same name. It got to number 19 in Canada, number 22 in the US and, strangely perhaps, number 1 in Spain. The line “No static at all” is better known and sometimes thought to be the title. When I was an early teen, music was mostly heard on AM (or Amplitude Modulation) radio which had quality problems although great propagation. At night, I would listen to the latest hits on WOWO Fort Wayne Indiana, a small city roughly 500 miles from where I lived. Particularly in the car, WOWO was the clearest station at night. Local AM was plagued by static and a way-too commercially oriented business model driven by the 2-minute-and-39-second hit single. FM or Frequency Modulation was not digital (too early for that) but, at a much higher radio frequency, had far better sound quality and, at that time, was the only way to hear so-called longer ‘album-oriented rock’. (Nothin’ but blues and Elvis / And somebody else’s favorite song.) However, FM had propagation challenges and while the sound quality was fantastic, it could not be picked up outside of major cities. There was no FM radio in Belleville Ontario where I went to high school and my first experience with it was CHUM-FM when I went to university in Waterloo, about one hour outside Toronto. The connection between WiFi / wide-area cellular and AM / FM may be a bit of a stretch, but you get the idea. To complete the technological connection, the song was not a huge hit, but Steely Dan’s recording engineer, Roger Nichols, won the 1979 Grammy for Best Engineered Recording, Non-Classical record

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