美国作业代写：Spectrum crisis

下面为大家整理一篇优秀的assignment代写范文- Spectrum crisis，供大家参考学习，这篇论文讨论了频谱的危机问题。有学者曾经说过，频谱紧缺将是全行业面临的问题。但这样的结论却不被人们所认可。因为频谱“紧缺”只在非常特定的场合和时间才会出现。有时使用一些替代手段就可以完全解决这些小范围的问题。

Next time you watch a ball game or concert, take a look around. You'll see thousands of fans taking photos, videos and sending them to friends. A large number of smartphone and tablet users have led to a sharp increase in mobile data traffic: According to Cisco estimates, mobile data traffic will increase to 18 times by 2016. Bell Labs predicted that the figure would be 25 times. Intuitively, this is a problem: all these photos and videos are transmitted by radio waves. However, only a fraction of the radio spectrum was sold to wireless operators for $ billions of. Most of the bands are reserved for other uses, such as radio and television, aviation and military applications. The rapid growth of data traffic has led operators to set a traffic cap and raise prices. There is no doubt that these two basic facts ―― the explosive growth of data use and the limited spectrum resource ―― must mean that we will soon not have enough bands to support all digital devices, right?

Just two years ago, the Federal Communications Commission chairman Julius Genachowski made the same point. He said the US wireless industry desperately needed to use the underutilized spectrum controlled by the government and radio and television agencies. Otherwise, wireless operators will not be able to meet the user's bandwidth requirements. "If we sit idly by the looming spectrum crisis, the imbalance between supply and demand will cause many consumers to face higher prices." "The spectrum Crunch is a problem for the industry," said Jim Cicconi, vice president of at Inc.

But the conclusion is premature. First of all, the spectrum "scarce" only occurs in very specific occasions and time. Sometimes these small-scale problems can be solved completely by using some alternative means. For example, looking around the stadium for four weeks, you may find that there are boxes of milk boxes on the rafters. These are short-range wireless receivers that use the unauthorized part of the spectrum. Your phone can send data through them without having to rely on long-distance phone bands. These wireless network receivers receive data and then transmit the data to the stadium via a wired network connection. The data you send to almost everyone in the stadium will not take up the precious spectrum that mobile operators claim to have. And this clever approach is just one of the new strategies and new technologies that can be useful.

Inefficient distribution management of the entire spectrum system. A recent advisory report to the White House clearly illustrates this and emphasizes that a wider sharing of wireless spectrum can increase its capacity by thousands of times times. For example, a large proportion of radio and television and state-specific bands have not been used. One reason is that there are only three local television stations in some areas, so that the rest of the dedicated spectrum of television broadcasts is not being used. Or a military weapon system that occupies a large band in Santiago, but is used little or no use in New York. "We are not so much in the spectrum crisis as it is a spectrum policy crisis," he said. "Microsoft's vice president for technology policy, former MIT professor and Intel company manager David Tennenhouse said. "The so-called ' spectrum crisis ' is really just an artificial spectrum resource shortage."

To more accurately record this man-made spectrum Crunch, Microsoft launched the Microsoft Spectrum Observatory project to monitor when and where the radio bands are actually used. Monitoring began in Washington, D.C., Seattle and Redmond, Washington. He hopes the work will take the first step towards a more massive collection of data in the future, creating more flexible regulatory measures for spectrum resources. He points out that the use of a short range of open, unlicensed Wi-Fi wireless networks has quickly been successful. "The challenge now is to spread these proven successes by using other underutilized bands to achieve broadband access in a wider area." ”

Some early work on spectrum sharing has begun. For example, some unused TV bands in an area can be used by other devices. Also, the Federal Communications Commission in December 2012 proposed to allow researchers and businesses to use the frequency of the radar system retained.

More wireless spectrum can be shared through cognitive radio technology. This technique can perceive the available spectrum and change the frequency within milliseconds to avoid interference with other devices. The University of Colorado is conducting its first outdoor tests. The technology is also being studied at Virginia Tech University, UC Berkeley and Rutgers University. At least so far, however, strict regulations do not allow for large-scale use of flexible technologies such as cognitive radio.

Of course, the spectrum crisis is not just a cover. The radio spectrum is a limited resource, and some of these frequencies are not very suitable for long-distance communication. Wireless operators cannot endlessly build new base stations on top of office buildings or on mountains, as these signals will sooner or later interfere with other base station signals. However, the short range transmitter and receiver with special frequencies can completely compensate for the shortage of coverage. The smallest of these small cells is called the home base station, which costs as low as $200 to meet the needs of the home and office. They can reduce the load of large base stations like the WiFi devices in the stadium. "Small honeycomb is now the hottest topic in the wireless industry. "said Jeff Reed, director of the Radio Research Laboratory at Virginia Institute of Technology.

John Donovan, executive vice president of at, said in the fall of 2012 that although at had purchased additional spectrum rights and was planning to buy more, the immediate crisis had been lifted and that the new demand for half 2015 would be solved through small-scale cellular solutions. Such technology is far more aggressive than expected. "A few years ago, you might have said that we'd run out of all the spectrum today." "Vanu, founder of the Wireless communications company in Cambridge, Massachusetts, said Vanu Bose. Vanu and Reed are technical advisers to the White House advisory report. In fact, there are many ways to solve the demand problem. Increasing the spectrum is certainly one of them, small honeycomb, other offloading technologies, and innovative technologies that we haven't thought of yet. ”

One day, the new technology will make wireless data transmission speed up greatly, thus releasing more bandwidth. For example, researchers at the Massachusetts Institute of Technology have confirmed that reciprocating communications for processing data packets can be cut. Although the technology is likely to be widely used in a few years, experiments have shown that it can increase capacity by 10 times. This means you can download the video at 10 times the current speed, freeing up bandwidth for others to use faster.

So can new technologies always avoid the problem of spectrum shortages? Maybe not, but Microsoft's house of Trent says decades of research are ready to solve the problem: "Now, we have a new technology and architecture that has been accumulating for 15-20 of years ... They can be used for a long time.”

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