Fiber backhaul should be good news for mobile subscribers who want to keep using more data. Once a bundle of optical fibers is installed, it can carry more data almost without limit as long as the equipment on either end of the fiber is upgraded. But that will require an ongoing commitment by the carriers, who each will have to buy new optical gear for 40,000 or 50,000 base stations to keep boosting capacity, an expensive proposition, Gillott said. Another advantage to fiber is that it's better suited to the precise timing requirements of LTE, Gillott said.
Another new variable in the backhaul equation is the introduction of small cellular and Wi-Fi base stations. Carriers don't yet know how many of these they will end up using, Gillott said. Collections of small cells may themselves be meshed together across areas where fiber or microwave can't easily be deployed, but the cumulative traffic from a mesh of cells may require one of the biggest backhaul links, such as a 1Gbps fiber connection, he said.
The trend is likely to be similar outside the U.S., with the difference that microwave makes up more of the backhaul, especially in Europe and Latin America, for various regulatory and competitive reasons, Gillott said. He expects that difference to remain.
Backhaul is an element of a mobile network where there are no shortcuts for the operators, Gillott said. "They are aware of the problem, they're aware of the danger, they just have to spend the money and do it."