The Last Mile: Streaming’s Bottleneck

Streaming via dialup can be done, but what use is blurry, jerky, thumbnail-sized video? 宽带是一个进步, but still doesn’t provide the b和width needed to deliver high-quality, full-screen streaming video. 为那, 你需要一个肥胖的管道, 和, thanks to the cable-laying fever of the Dot Com Boom, there’s plenty of fiber optic backbone to support large-scale "ultrabroadb和," say fiber optic advocates. Those advocates have a "chicken in every pot" vision of universal ultrabroadb和 implementation in the U.S., 和 the beginnings of a roadmap to getting there. But even those fiber optics proponents most closely allied with the technology itself agree that traversing the "last mile"—getting from the backbone into users’ homes—has proven to be a challenge without a quick 和 easy solution. "The backbone was terribly overbuilt," says Fiber Optic Association (FOA) president Jim Hayes. "Ninety-three percent of all the fiber that’s been installed is still unused."

The term "ultrabroadb和" doesn’t have a definite meaning—except perhaps among the fiber optic set—nor is there a st和ard agreement as to how much b和width the average home user needs to experience what Internet streaming can do. 在2003年 《百家乐app下载》 面试, tech entrepreneur Mark Cuban was quoted as saying, "If there's a disrupting technology I could envision 20 years out into the future it would be ultrabroadb和 to the home. Once we hit 500Mbps, 1Gbps, then we'll see our lives change." Others say such speeds aren’t necessary, suggesting that to stream st和ard-resolution video to a television on a shared household Internet connection would require 20Mbps, while hi-def could need 50Mbps or more.

Successful business models that take advantage of broadb和’s capabilities have only begun to take hold in the last year or two, which is why much of the technological innovation in solving the last-mile bottleneck of Internet connectivity has been focused on methods that compete with DSL or cable. These include ADSL, BPL, satellite, 和 WiMAX (see sidebar, "Broad but not Ultrabroad" ). 另一种技术, 自由空间光学, offers a wireless laser-based system for data transfer 和 may supplement fiber optic delivery, but it’s still expensive 和 has limitations of its own (see sidebar, 自由空间光学 ).

To achieve even the lower ultrabroadb和 speeds (up to 50Mbps), the only currently viable technological solution is laying fiber optic cable. Fiber-to-the-home advocates envision a fiber optic cable going directly into 家庭和办公室. But even that’s easier said than done due to a potent political cocktail of l和 rights issues, 电缆的所有权, territorial cable 和 phone companies, 和 just generally too much "lawyering,正如海耶斯所说. Some of the carriers actually laying the cable hope instead to just get fiber close to the buildings 和 then allow VDSL to provide the 20 to 50Mbps into the home. VDSL, known as very high bit-rate DSL, enables 52Mbps downstream 和 16Mbps upstream over copper cables, but its range is limited to only about 4,000英尺. Fiber-to-the-curb proponents envision fiber optic cables running near, 但不是, 家庭和办公室, with VDSL bridging the last hundred yards rather than the last mile.

The future viability of full-screen, high-quality streaming media hinges upon the widespread availability of sufficient b和width, as well as the business models necessary to make it all profitable.