问题 问答题 简答题

描述MIMO技术的三种应用模式.

答案

参考答案:

MIMO技术主要利用传输分集、空间复用和波束成型等3种多天线技术来提升无线传输速率及品质。

(1)传输分集:SFBC具有一定的分集增益,FSTD带来频率选择增益,这有助于降低其所需的解调门限,从而提高性能;

(2)空间复用包括:A.开环空间复用:对信噪比要求较高,会使其要求的解调门限升高,降低覆盖性能;B.闭环空间复用:对信道估计要求较高,且对时延敏感,这导致其解调门限要求较高,覆盖性能反而下降;C.MU-MIMO:多用户MIMO,有助于提高系统吞吐量。

(3)波束赋形包括:A.rank=1的闭环预编码:解调性能应比mode4在多层多码字传输时要好,相对mode1的覆盖性能应该仍然会有所下降;B.单天线端口:该模式应该具有较好的覆盖性能

单项选择题
阅读理解

A blog can be a very effective way of spreading the words about yourself, and your other writing. It can unshroud your knowledge, and create an ongoing relationship with your readers. A good blog is more than just a marketing tool; it’s also an expression of your personality.

An obvious starting point is to post samples of your work that not only show off your skills and writing ability but also leave people wanting more. Post selections from the most exciting parts of your stories but end them just as the action reaches its peak. If you write nonfiction (写实文学), show people what they could achieve, and give them a few steps to get them started.

Give tips, information and advice about the subjects you cover. For example, something about struggling with difficulty and many other issues like this. Your writing tips can also be included, as well as interesting, strange or funny things you discovered during your research. Whenever you contact an expert, ask if he or she has any interesting stories you could use. You may also give background information about your stories and the locations.

Give details of coming posts on your blog, so people can watch out for you, or come and meet you. Personal news will help people feel better connected to you. Include photos of objects and locations in your writing, famous people you meet, the views from your window, and your favorite things—with a note about where they came from and what they mean to you. Look out for things that will help your readers get to know you better, know the subject better, or anything else you think they might find useful, inspiring or entertaining.

If you only occasionally post things on your blog, people have a tendency to forget you. As a writer you shouldn’t ever run out of interesting materials to fill your blog with—and your readers will love you for it.

小题1:Which is the best title for the text?

A.What to Blog about

B.How to Start a Blog

C.Why to Launch a Blog

D.How to Make Website Attractive小题2:The underlined word “unshroud” in the first paragraph means ________.

A.hold out

B.turn up

C.show off

D.put down小题3:You’d better blog about ________.

A.the difficulties of your position to readers

B.the entertaining stories you have

C.advice about your readers’ subjects

D.masterpieces from famous writers小题4:What does the author suggest for keeping a blog?

A.Posting things on your blog once in a while.

B.Adding new stories to it every day.

C.Filling it with attractive things frequently.

D.Loving it as your life.