OFDM的英文是()
A.OverloadFrequencyDivisionMultiplexing
B.Orthogonal?Frequency?Division?Multiplexing
C.Overwhelming?Frequency?DivisionMultiplexing
D.Outstanding?Frequency?Division?Multiplexing
在LTE系统中,为了支持成对的和不成对的频谱,支持频分双工(Frequency Division Duplex,FDD)模式和时分双工(Time Division Duplex,TDD)模式。LTE支持两种类型的无线帧结构:类型1,适应于全双工和半双工的FDD模式,类型2适应于TDD模式。()
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在通信专业中,WDM的英文全称是(),“吞吐量”英文通常翻译为()。A.Wierless Digital Modulation B.Wave Division Multiplexing C.Wavelength Division Multiplexing D.Wireless Data Modulation A.traffic flow B.rate C.throughout D.throughput
对于LTE物理层的多址方案,在下行方向上采用基于循环前缀(Cyclic Prefix,CP)的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM),在上行方向上采用基于循环前缀的单载波频分多址(Single Carrrier-Frequency Division Multiplexing Access,SC-FDMA)。()
F-OFDM英文全称是Flexible Orthogonal Frequency Division Multiplexing,中文叫灵活的正交频分复用。()此题为判断题(对,错)。
Which two statements are true about optical networks?()A. SONET and SDH both use time-division multiplexing.B. An optical transport network system uses time-division multiplexing.C. SONET and SDH both use wavelength-division multiplexing.D. An optical transport network system uses wavelength-division multiplexing.
The use of pulse groups and extremely precise timing at each Loran-C station makes possible the use of ______.A.High frequency pulsesB.Combinations of high and low frequency pulsesC.The same frequency for all stations in a chainD.Varied long and short pulses
The traditional way of allocating a single channel among multiple competing users is to chop up its ( ) by using one of the multiplexing schemes such as FDM (Frequency Division Multiplexing). If there are N users, the bandwidth is divided into N equal-sized portions, with each user being assigned one portion. Since each user has a private frequency ( ), there is no interference among users.When there is only a small and constant number of users, each of which has a steady stream or a heavy load of ( 本 题 ), this division is a simple and efficient allocation mechanism. A wireless example is FM radio stations. Each station gets a portion of the FM band and uses it most of the time to broadcast its signal.However, when the number of senders is large and varying or the traffic is ( ), FDM presents some problems. If the spectrum is cut up into N regions while fewer than N users are currently interested in communicating, a large piece of valuable spectrum will be wasted. If more than N users want to communicate, some of them will be denied ( ) for lack of bandwidth.?A. traffic B. date C. bursty D. flow