Two years ago, we published an article that described a "trigger point" for small cells, based on something that we called the "Super Bowl Index". It was a fun back-of-the-envelope calculation that we did with our mobile operator buddies over a beer. No kidding, that's what we do for fun.
We tracked the amount of mobile data major sporting events…. the Super Bowl in American football, a FIFA world cup, an Olympic event. The density of traffic is extreme in these situations, well above the density of a normal urban network. The "Super Bowl Index" goes something like this: We calculate the density of traffic in terms of GB of data in the peak hour, and compare that with the density of mobile users in the city.
We found that a major American city reaches "Super Bowl" levels of data traffic between 2 and 3 years after its benchmark sporting event. New York City has recently reached 2013 Super Bowl levels of traffic density in its hotspots. We can expect San Francisco to reach the level of the 2015 Super Bowl in about 2017.
Calculations on a cocktail napkin are great fun, but there is a more useful and practical outcome here. We started tracking mobile traffic density for several operators two years ago, and we've noticed correlations which can predict when and where small cells will become necessary.
Mobile Experts collects numbers on data density from a few mobile operators scattered around the world. Normally we can get an estimate of density in terms of Gbps of LTE data demand in a small area such as a single macrocell sector. This allows us to estimate geographic density in Gbps/km2. We also take spectrum into account, because operators with less spectrum naturally feel more pressure at high levels of capacity. The best metric to use is mobile density, measured in Gbps/km2/MHz, or GkM.
When we look at the GkM levels for various world cities, we see some major differences based on level of data consumption, spectrum allocations, and population density.
Seoul's busy subway has dense mobile traffic, with strong data demand per user and a tight concentration of people. Korean operators have wide spectrum allocations with a total of 145 MHz of spectrum available (70+ MHz of paired spectrum), but their high usage results in a high density.
American cities have lower traffic demand, and similar spectrum availability, so they have somewhat lower GkM values. UK operators have plenty of spectrum, so London has lower mobile density despite strong traffic patterns.
For comparison, in Latin America the traffic is growing but it's not as concentrated as in other areas. Still, in Copacabana Beach the GkM value is similar to London because Brazilian operators have less spectrum.
Korean and Japanese operators started to deploy small cells in 2011 and 2012, when their mobile density crossed the threshold of 0.02 GkM. We now see that level of density in New York, and as predicted we now have American operators deploying small cells for traffic density in cities like New York and Boston, where spectrum is more expensive. We should see similar levels of mobile density in San Francisco and London within the next year.
Mobile Experts will be expanding this model to compare networks in as many countries as possible, so any mobile operators that would like to participate should contact us.
Joe Madden is Principal Analyst at Mobile Experts LLC. Mobile Experts is a network of market and technology experts that provide market analysis on the mobile infrastructure and mobile handset markets. He provides market forecasts for handset, DAS, small cell, and base station markets, with in-depth research down to the nitty gritty details of frequency bands and power levels. Mr. Madden graduated, cum laude, from UCLA in 1989 and is a Silicon Valley veteran. He has survived IPOs, LBOs, divestitures, acquistions, and mergers during his 24 years in mobile communications.