To combat the explosion of data traffic hitting their mobile networks, operators around the world (in both developed and developing economies) have been looking to migrate to 4G or, as it’s also known, 3GPP Long Term Evolution (LTE).

LTE was designed to increase both the capacity of current 3G networks, by as much as 1.5 to 2x as estimated by experts such as Peter Rysavy.

The LTE specification is said to provide downlink peak rates of at least 100 Mbps and uplink rates of 50 Mbps — but subscribers will only see these kinds of rates if they’re the only person in the cell, and under ideal conditions.

As with all other cellular radio technologies, air interface capacity is shared in LTE between all active users in the cell, and that capacity is highly dependent on the quality of the radio environment in use.

Cautions about not mistaking peak rates for sustainable multi-user throughput aside, even in the aggregate that bandwidth sounds pretty good, so then who needs Wi-Fi?

Some LTE enthusiasts think that Wi-Fi is simply a short-term bandaid for today’s overtaxed 3G networks, and that it will fade from relevance to the mobile operator scene once LTE is widely deployed. A closer look at the facts reveals that Wi-Fi is destined to play a longer-term and complementary role right alongside LTE.

The inescapable reality is that while LTE and 3GPP advances increase capacity in a linear fashion, demand for capacity is growing exponentially (see left chart).

Yes, industry analysts have been forecasting the mobile data “hockey stick” for a long time, but the advent of mass-market smartphone adoption over the past couple years has proven beyond any doubt that we are headed up this curve. Moreover, as mobile service revenue growth slows (driven by increasingly flat-rate pricing), operators need to leverage any and every tool at their disposal.

Wi-Fi remains one of most attractive cost structures for high capacity urban and suburban areas of any wireless technology on the planet [see right chart]. Installation of additional macro/femto equipment or licensed spectrum is costly. In contrast, Wi-Fi is a cost-efficient alternative for traffic with low QoS demand, with 550MHz of unlicensed spectrum and a large (often underappreciated) installed base.

Think of it this way: LTE will be used primarily for the macrocell environment and high mobility where licensed-band performance characteristics are essential while Wi-Fi will be used for an underlay of smaller cells where high capacity density with minimal visual footprint and infrastructure cost will be key.

In addition to its attractiveness in addressing fundamental bandwidth demand v. supply gaps, emerging Wi-Fi solutions’ technical advances in the areas of Wi-Fi/3GPP interoperability, inter-network roaming (for service continuity), and seamless authentication and single sign-on have given operators new-found respect for Wi-Fi as a strategic asset.

Now combine these with radio breakthroughs in adaptive RF signal controls (i.e. dynamic beamforming) and RF interference rejection that make the unlicensed bands trustworthy, and Wi-Fi suddenly has the carrier-class reliability for large-scale public services.

Of course, we don’t want you to be confused into thinking we’re advocating Wi-Fi as the answer to all the mobile world’s problems (which, given our vantage point, you might understandably assume). Our mobile network operator customers assure us that in a 4G world, they will need to use anything and everything they can (more unlicensed spectrum, femtocells, picocells, bigger/better backhaul, etc.)to meet the skyrocketing demands on their networks. There is no one silver bullet.

That said, with hundreds of millions of powerful new Wi-Fi enabled devices now in the hands of our children, you can bet that in both the immedate and long term, operators will use better Wi-Fi everywhere to address this Mobile Internet craze and the resulting broadband landgrab currently underway.