機(jī)上Wi-Fi已經(jīng)越來(lái)越普及，相關(guān)技術(shù)也在一直進(jìn)步,，以滿足日益增多的需求,。

在此介紹兩個(gè)在飛機(jī)上使用Wi-Fi的方法，一種要借助專(zhuān)門(mén)的地面手機(jī)信號(hào)塔,，另一種要利用通信衛(wèi)星,。

但飛機(jī)上的Wi-Fi究竟如何發(fā)揮作用呢？作為全球最大空中互聯(lián)網(wǎng)服務(wù)供應(yīng)商之一,，Gogo既利用地面信號(hào)塔,，也依靠全球人造通信衛(wèi)星，服務(wù)的航空公司包括達(dá)美航空,、美國(guó)聯(lián)合航空,、阿拉斯加航空和維珍航空等。負(fù)責(zé)外聯(lián)和公關(guān)的Gogo副總裁史蒂夫·諾蘭向我們解釋了服務(wù)運(yùn)行的具體情況,。

手機(jī)信號(hào)塔怎樣實(shí)現(xiàn)機(jī)上互聯(lián)網(wǎng)服務(wù),？

第一種實(shí)現(xiàn)機(jī)上Wi-Fi的方法是地面手機(jī)信號(hào)塔,，工作原理跟向手機(jī)提供Wi-Fi網(wǎng)絡(luò)類(lèi)似。

具體來(lái)說(shuō)就是將大型信號(hào)塔指向天空,，向飛過(guò)的飛機(jī)傳輸Wi-Fi。無(wú)線服務(wù)商向手機(jī)提供信號(hào)時(shí),，信號(hào)塔則定向地面,。由于航空公司的信號(hào)塔向天空發(fā)射信號(hào)，覆蓋范圍會(huì)更廣,。

“無(wú)線電波的覆蓋范圍是個(gè)錐形體,，”諾蘭說(shuō)，“信號(hào)塔距離地面很近,，所以發(fā)射范圍不會(huì)很大,，想實(shí)現(xiàn)覆蓋就需要更多塔。向天空傳輸信號(hào)時(shí)覆蓋范圍會(huì)大得多,?！?

人造衛(wèi)星怎樣實(shí)現(xiàn)機(jī)上互聯(lián)網(wǎng)服務(wù)？

如果使用人造衛(wèi)星提供Wi-Fi,，飛機(jī)可以通過(guò)機(jī)身上部的天線接收信號(hào),。人造衛(wèi)星運(yùn)用的頻率和手機(jī)信號(hào)塔不同，不但提供的上網(wǎng)速度更快,，而且在水域也可以實(shí)現(xiàn)聯(lián)網(wǎng),。

越來(lái)越多航空公司接受了這種新技術(shù)。據(jù)諾蘭介紹,，雖然業(yè)內(nèi)有其他網(wǎng)絡(luò)提供商競(jìng)爭(zhēng),，已有1600架飛機(jī)將選用Gogo的人造衛(wèi)星技術(shù)。

捷藍(lán)航空自2013年起提供機(jī)內(nèi)聯(lián)網(wǎng)服務(wù)FlyFi,，今年1月成為首家實(shí)現(xiàn)空中免費(fèi)高速上網(wǎng)的航空公司,。捷藍(lán)航空的發(fā)言人表示，提供FlyFi服務(wù)的人造衛(wèi)星由ViaSat和Thales等公司制造,，目前美國(guó)境內(nèi)各航線均已實(shí)現(xiàn)覆蓋,。

機(jī)上Wi-Fi在任何地方都可以用嗎，是否包括海洋上空,？

飛行途中能否用Wi-Fi取決于航空公司選用哪種服務(wù),。比如諾蘭提到，Gogo的空對(duì)地技術(shù)利用手機(jī)信號(hào)塔實(shí)現(xiàn)Wi-Fi時(shí),，只在陸地上空才能接收到信號(hào),。使用人造衛(wèi)星提供Wi-Fi能在跨海時(shí)聯(lián)網(wǎng)，不過(guò)覆蓋范圍不夠全,，信號(hào)可能偶爾中斷,。此外飛機(jī)途徑地球兩極時(shí)也會(huì)收不到信號(hào),。

機(jī)上Wi-Fi網(wǎng)速有多快？

諾蘭說(shuō),，因?yàn)楣?yīng)商和使用服務(wù)不同,，機(jī)上Wi-Fi的速度也會(huì)有差別。Gogo的空對(duì)地服務(wù)利用手機(jī)信號(hào)塔時(shí),，整架飛機(jī)共享9 Mbps的下載網(wǎng)速,，而人造衛(wèi)星提供的Wi-Fi可為每位乘客提供15 Mbps的網(wǎng)速。捷藍(lán)航空的發(fā)言人稱(chēng),，在信號(hào)覆蓋范圍內(nèi),，F(xiàn)lyFi可實(shí)現(xiàn)人均網(wǎng)速12到20 Mbps。對(duì)比來(lái)看,，美國(guó)互聯(lián)網(wǎng)服務(wù)商Xfinity和Fios提供的寬帶網(wǎng)速在10 Mbps到500 Mbps之間,。（財(cái)富中文網(wǎng)）

譯者：Pessy

審稿：夏林

As in-flight Wi-Fi becomes more common, the technology has been changing to meet growing demand.

There are two methods for bringing Wi-Fi to planes. One uses special ground-based cell towers, while the other uses satellites.

But how exactly does Wi-Fi work on planes? One of the biggest providers of inflight internet, Gogo, uses both ground-based towers and satellites around the world, which service airlines including Delta, United, Alaska Airlines and Virgin Air. Here, Steve Nolan, vice president of communications and public relations for Gogo, explains how these services work.

How do cell towers power in-flight internet?

Ground-based cell towers, which was the first method of delivering in-flight Wi-Fi, are similar to the same towers that deliver Wi-Fi to cell phones.

The large towers project wireless service by pointing toward the sky, delivering Wi-Fi to planes flying overhead. In contrast, towers used by wireless providers direct coverage toward the ground. Turning the coverage toward the sky allows airline towers to have a larger coverage area.

"If you think about how a radio wave works, it goes out like a cone," Nolan said. "So you need many more ground towers because they're closer to the ground and the beam doesn't wide out as much. When it points upwards, it widens into a much larger space."

How do satellites power in-flight internet?

With satellite powered-Wi-Fi, planes connect to the internet using an antenna mounted on top of the plane. Besides using a different frequency than cell towers, satellite-powered service also allows planes to provide faster service and can be used over water.

This new technology has been embraced by more and more airliners. According to Nolan, 1,600 planes are committed to installing Gogo's satellite technology, though other companies also offer the service.

JetBlue, which became the first airline to offer free high-speed internet on all of its planes in January, has been offering its FlyFi service since 2013. A JetBlue spokesperson said the company uses satellites from companies including ViaSat and Thales for its FlyFi service, which is offered on its flights within the U.S.

Can you use plane Wi-Fi anywhere (including oceans)?

Where you can get Wi-Fi while flying depends on the service your airline uses. For example, Gogo's air-to-ground technology uses cell towers and only works when above land, according to Nolan. Their satellite Wi-Fi can work overseas, though there can be gaps in coverage. The service also will not work over the North and South poles.

How fast is in-flight Wi-Fi?

In-flight Wi-Fi speeds vary based on the provider and the service used. According to Nolan, Gogo's air-to-ground service, which utilizes cell towers, gives customers 9 Mbps for the entire aircraft and satellite offerings provide 15 Mbps per person. JetBlue's FlyFi has speeds ranging between 12 and 20 Mbps per person when within the coverage area, according to a JetBlue spokesperson. In contrast, U.S. internet providers Xfinity and Fios offer internet speeds ranging from 10Mbps to 500 Mbps.