Wireless carriers will see mobile data traffic increase 26 times between 2010 and 2015 according to Cisco's latest Visual Networking Index Forecast. Will wireless operators be ready for it

That's the big question. The prediction of steep increases in traffic load are not entirely unexpected. Wireless carriers have been preparing for traffic increases by adding more capacity not only to their radio networks, but also in the back-haul networks that carry the traffic from the radio towers to the Internet.

By 2015, Cisco says that mobile data traffic will grow to 6.3 exabytes of data or about 1 billion gigabytes of data per month. The report indicates that two-thirds of the mobile data traffic on carrier networks in 2015 will come from video services. This trend follows a similar trend in traditional broadband traffic growth. And it suggests that as wireless networks get faster, devices get more processing power with bigger and better screens, people will increasingly watch more video on the go.

"What we're seeing here is true convergence," said Doug Webster, Cisco's senior director of worldwide service provider marketing. "We've talked about this for a long time, but it's really starting to happen where people are doing all the things they used to do on broadband connections at home when they're on-the-go."

But according to Cisco's results, mobile data traffic is actually growing faster than traditional landline-based broadband traffic. In 2010 data traffic grew 159 percent, which is roughly 3.3 times faster than traditional landline broadband. And it was higher than the 149 percent growth rate Cisco had predicted in earlier Visual Networking Index reports. But over the next five years, the growth should taper off, Cisco's report indicates. For example, annual growth rates are expected to go from 131 percent in 2011 to 64 percent in 2015.

So what exactly is driving the growth The first main driver is the proliferation of mobile devices, said Suraj Shetty, a Cisco marketing vice president. Last year, Cisco's Index predicted that the smartphone installed base would increase 22 percent in 2010, but Informa Telecoms and Media data indicates that the number of smartphones in use grew by 32 percent during the year, Cisco said. In addition to the increase in smartphone adoption, there was a sharp increase in those smartphones that have the highest usage profile: iPhones and Android phones. The number of iPhones and Android devices in use grew 72 percent in 2010, bringing the combined iOS and Android share of smartphones to 23 percent, up from 11 percent in 2009.

And the trend is only expected to continue, especially as devices other than smartphones are added to the mix. By 2015, there are expected to be 5.6 billion mobile devices and 1.5 billion machine-to-machine devices in the world. These devices will include mobile phones, as well as Internet-connected cameras, Net-connected cars, tablets, laptops and more devices.

In addition to simply having more devices connected to wireless networks, more of these devices will also have better computing capabilities, Shetty added. We're already starting to see this with smartphones running dual-core processors. The screens on mobile devices are also getting bigger and sharper. Not only are tablets coming on the scene, but smartphones themselves are getting larger and will have greater computing capacity than devices available today.

Network speeds are also increasing as wireless operators move to new generations of technology. In the U.S. wireless operators are talking about their "4G" wireless networks, which can offer download speeds anywhere between 5Mbps and 20Mbps, depending on the technology used. T-Mobile USA and AT&T have their HSPA+ networks. And Verizon Wireless has its LTE network. (AT&T also plans to launch an LTE network this year.) And Sprint Nextel has its WiMax network.

Cisco's report indicates that network doubled in 2010 and speeds will only increase over the next five years with the average download speeds expected to increase 10-fold by 2015.

The faster speed networks, more capable devices with better screens, and the plain fact that there will be more connected devices in five years, means that wireless consumers will use more resources.

"There will be more devices with bigger screens and better processors that allow for multiple apps to run simultaneously, and the predominant type of network traffic will be video," Shetty said. "These trends are all coming together and will have a significant impact on the network."

What it means for wireless operators is that they need to find a way to keep up with the growing demands on their networks. In the wireless world, the need to keep up with growing demand means a need for more wireless spectrum. Carriers such as T-Mobile say they have enough spectrum today to meet current growth projections. But they say more is needed down the road.

This is why the Federal Communications Commission is working to get an additional 500MHz of wireless on the market in the next decade with a plan for 300MHz spectrum to be freed up in the next five years.

But adding more spectrum takes time and it will not be enough to solve the capacity crunch that wireless operators will likely face in the next few years. Shetty said that wireless operators will have to get more efficient in how they use their network resources. Shetty said that Cisco has technology that can help wireless operators improve network efficiency.

"There are lot of demands and challenges that carriers face to keep up with demand," he said. "Cisco can help them better engineer the network. And allow them to scale the network."

But carriers will also have to invest in other network technologies to help keep up with demand. This will likely include offloading traffic onto femto cells and Wi-Fi networks.

It may also mean shifting business models to encourage consumers to use mobile data more efficiently. Last June, AT&T eliminated its unlimited data plan and began offering a tiered data service offering with usage caps. Other wireless operators in the U.S. haven't followed yet. But Verizon Wireless, the largest U.S. wireless operator, has indicated that it will move to tiered pricing. Whether it gets rid of an unlimited entirely is still unknown. But it's likely the company will raise the price of unlimited if it keeps it all.

The other wild card in this whole scenario are tablets and other connected devices. While more people in the world today have cell phones than have electricity, devices such as tablet PCs will eat up capacity even further, because they can do so much more than many mobile handsets.

It doesn't take nearly as many tablets in the world to have a significant effect on network loads. For example, a smartphone generates about 24 times more data on a wireless network than a basic feature phone. But a tablet generates about 122 times more data consumption than a basic feature phone, according to Cisco.

Webster said a year ago, tablets weren't even on the radar screen when it came to predicting future mobile data growth. But with the introduction of the Apple iPad last year and now a growing number of tablet PCs, the category is expected to have a significant effect on data usage patterns in the next five years.

"Last year there was zero data traffic on the network from tablet PCs," Webster said. "And it went from basically nothing to being a significant contributor to mobile network traffic by 2015. This is just indicative of how dynamic this market is with one type of device ramping up so quickly. It has huge architectural implications."