Wireless Depends on Wireline Expansion to Meet Exploding Demands, Hatfield Says
Another 500 MHz of spectrum for wireless broadband won’t meet exploding demand without changes in how carriers use spectrum, former FCC Office of Engineering Technology Chief Dale Hatfield warned. In a speech at an Information Technology and Innovation Foundation event late Tuesday on the future of digital communications, he also said the commission needs to put more focus on how wireline and wireless solutions can work together to solve the spectrum crisis. “It’s not going to be enough,” Hatfield said. “If the government finds 500 MHz, we're going to chew that bandwidth up really, really, really fast. That’s sort of the challenge, if you will.”
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There are two ways to expand capacity, Hatfield said: One is to get more bytes per second per hertz out of spectrum, similar to increasing the miles per gallon used by a car. Wireless systems remain inefficient, he said, with the average cellular system having an efficiency of 1.4 bps/Hz, versus 20 Mbps in a 6 MHz digital TV channel and 43 Mbps in a 6 MHz channel downstream in a modern cable system.
The other way is to get more spectrum reuse, by decreasing the size of cells. “We can take that 500 MHz of spectrum and we can use it in a great big cell across the whole downtown here and we wouldn’t get very many simultaneous conversations or sessions,” Hatfield said in Washington. “On the other hand, by bringing the size of the cell down smaller and smaller then you can use that 500 MHz multiple times. That’s the whole basis of the cellular architecture.”
"Where does that lead us?” Hatfield asked. “At the extreme, of course, there could be just one cell that covers this room and a different cell covers the lobby and you could reuse that same spectrum in the two places without interference if you shrink the cell size.” To get that kind of efficiency, wireless depends on wireline deployment, Hatfield said. “That’s going to take an awful lot of fiber awful close to the subscriber,” he said “That traffic has got to be able to get back to some central location, some switch or traffic concentration point.” Policymakers will need to recognize that for wireless’s growth to continue it will require fiber deployment, he said. The tendency today at the FCC is to look at wireless and wireline issues “somewhat separately,” Hatfield said.
The panel offered diverse commentary from experts asked to write about different aspects of the digital future, in a program also sponsored by Time Warner Cable. The papers are at http://events.r20.constantcontact.com/register/event?oeidk=a07e32gs4hi51b474d2. Scott Wallsten, economist and vice president of the Technology Policy Institute, called for more focus on business broadband. The FCC’s focus so far has been mostly on data that residential broadband, said Wallsten, who was economics director to the FCC’s Broadband Task Force. “In Washington, there’s strong demand among politicians for things that create jobs and economic growth,” he said. “The residential part of broadband, while it’s important for various reasons, is not what’s necessarily related to economic growth, to productivity. It’s how enterprises are going to use [broadband] connections and we know very little about that."
"We have information about how many households are connected, how many connections per 100 people, what speeds people connect to more or less. We're beginning to get a little information on what people pay,” Wallsten said. But “there’s not a strong link between residential use and economic growth,” he said. Mostly residential broadband is used for entertainment, he said. “Even things that you do in an economic sense represent economic transfers, so if you buy a book from Amazon instead of the local bookstore, that’s not a net economic gain, that’s just a transfer.”
ITIF President Robert Atkinson noted the lack of broadband connectivity at most U.S. hotels. “I have more bandwidth in my house in Bethesda [Maryland] than this hotel probably has,” he said. “I don’t know about this hotel, but the Marriotts, whatever, they're getting 10, 15 megabytes” of capacity. Wallsten responded: “Does that mean something and if so, what?” Atkinson joked, “I think the answer is clear -- It’s USF for hotels.”
There are many unanswered questions about business broadband, Wallsten said. For example, many businesses use T1 lines, which only offer 1.5 Mbps of capacity. “That sounds really, really slow, but there are other things about those connections they like -- the symmetry, the guaranteed performance,” Wallsten said. Research on these issues is not well suited to Washington, he contended. “People in Washington want answers right now, because they want to do something, anything, right now, but the research takes longer to do.” When the answers are more complicated, “Washington doesn’t like that,” he said.
University of Pennsylvania Law School Professor Christopher Yoo stressed the role that engineers will have to play in solving problems posed by moving to a broadband world. “If an economist tells you, `well, this is definitely the answer,’ nowadays you'll say, `okay, there must be another side of the argument, let’s see what that is,'” Yoo said. “With lawyers, it’s even worse. ... Somehow, when an engineer says this is the answer, people will often nod their heads and say `well, that must be right.'” Engineers disagree just like lawyers and economists, he said: “They fight like crazy. They express opinions with great conviction"
FCC staff need to know more about engineering and to find ways to interact better with the engineers at the FCC, Yoo said: “I think it’s a great way for us to improve the quality of decisionmaking” at the commission.