How important is Wi-Fi offload to solving the capacity crunch? Extremely important, if new numbers from iGR are any indication. 

The amount of traffic moved from cellular networks to Wi-Fi in the United States doubled between last year and this year, according to data provided exclusively to Wireless Week from the market strategy consultancy's recent report on the issue.

"For the mobile operators, Wi-Fi offload can provide some relief for congested 3G and 4G networks," iGR President and founder Iain Gillott said.

The amount of data traffic from Wi-Fi offload is expected to post a 16-fold increase between last year and 2016, bringing it "about even" with the amount of data traffic generated by Wi-Fi-only devices such as tablets, laptops, eReaders and handheld gaming consoles, iGR said.

Over the next four years, iGR predicts that the amount of cellular traffic rerouted over Wi-Fi will reach 8 million gigabytes per month in the United States as operators like AT&T and Verizon Wireless step up their dependence on the offloading technique.

AT&T already has an extensive Wi-Fi network comprised of more than 30,000 hotspots. About two-thirds of those hotspots originated from AT&T’s 2008 acquisition of Wayport. 

Verizon’s tie-up with Cox Communications, Comcast, Time Warner Cable and Bright House Networks could allow its customers to access the cable provider’s 50,000-strong Wi-Fi hotspot network, dubbed CableWiFi.

“It is interesting that a lot of people have said, well, I can't believe you're going to partner with them. You are not going to use their Wi-Fi are you? Well, of course, we are,” Verizon Communications CEO Lowell McAdam said a June investor conference, referring to the company’s work with the cable providers. “We want to shift as much onto FiOS or onto the fixed network as we can.”

Though most offload today is driven by consumers - the end user decides whether to use Wi-Fi instead of a cellular connection - carriers are expected to play a bigger role in directing traffic off their macro networks. Technology like ANDSF (access network discovery and selection function) that allows operators to actively switch cellular traffic to Wi-Fi is just starting to emerge and will be "far more prevalent" by 2016, the iGR report stated.

Even as operators look to push more bytes onto Wi-Fi, the same market forces driving cellular traffic also affect Wi-Fi traffic. Gillott notes that the amount of data consumed by each offload connection will rise for the same reason mobile broadband use is on the rise: current customers are finding new uses for mobile data, and new subscribers are joining them. New technologies like the Wi-Fi Alliance's Passpoint solution will make it easier to connect to Wi-Fi hotspots, making it even easier for operators to get their customers to use Wi-Fi. 

More information about how Wi-Fi is used and detailed traffic forecasts for Wi-Fi offload is available in the full report.  Click here to purchase iGR's new Wi-Fi offload report.