大学MOOC 移动通信（陈万通）(中国民航大学)1450423197 最新慕课完整章节测试答案

第一章测验

1、判断题：
​In OFDM, the chosen subcarrier frequencies are spaced apart by the inverse of the symbol time, and the spectrum of each subchannel may overlap to fully utilize the available bandwidth.‌​‌
选项：
A: 正确
B: 错误
答案: 【 正确】

2、判断题：
‍In a cellular structure, a MS needs to communicate with the BS of the cell where the MS is currently located, and the BS acts as a gateway to the rest of the world.‏‍‏
选项：
A: 正确
B: 错误
答案: 【 正确】

3、判断题：
‌A BS consists of a base transceiver system (BTS) and a BSC. Both tower and antenna are a part of the BTS, while all associated electronics are contained in the BSC.‏‌‏
选项：
A: 正确
B: 错误
答案: 【 正确】

4、判断题：
‍HLR is located at the MSC where the MS is registered and where the initial home location for billing and access information is maintained.‎‍‎
选项：
A: 正确
B: 错误
答案: 【 正确】

5、判断题：
​The third and most promisingCDMAtechnique utilizes a wider frequency band for each user. As the transmission frequency is distributed over the allocated spectrum, this technique is also known as spread spectrum.‍​‍
选项：
A: 正确
B: 错误
答案: 【 正确】

随堂测验

1、判断题：
‌Octagons and decagons do represent shapes closer to a circular area as compared to a hexagon. Thus they can be used to model a cell.‎‌‎
选项：
A: 正确
B: 错误
答案: 【 错误】

2、判断题：
‎In TDMA, one channel is used by several users, with BS assigning time slots for different users, and each user is served in a round-robin method‏‎‏
选项：
A: 正确
B: 错误
答案: 【 正确】

3、判断题：
‎The actual shape of the cell, indicating a true coverage area, may be of a zigzag shape.‍‎‍
选项：
A: 正确
B: 错误
答案: 【 正确】

单元测验

1、填空题：
​In a DSSS method, the radio signal is multiplied by a pseudorandom sequence‍​whose （ ） is much greater than that of the signal itself, thereby spreading its‍​bandwidth‍​‍
答案: 【 bandwidth】

2、填空题：
‌This is a modulation technique wherein a pseudorandom sequence directly phase modulates a (data-modulated) carrier, thereby increasing the （ ） of the transmission and lowering the spectral power density (i.e., the power level at any given frequency).‌‌‌
答案: 【 bandwidth】

3、填空题：
​The resulting RF signal has a noiselike spectrum and in fact can be intentionally made to look like （ ） to all but the intended radio receiver.‍​‍
答案: 【 noise】

4、填空题：
​The received signal is （ ） by correlating it with a local pseudorandom sequence identical to and in synchronization with the sequence used to spread the carrier at the radio transmitting end‍​‍
答案: 【 despread】

5、填空题：
​In a FH method, a pseudorandom sequence is used to change the radio signal ( )‏​across a broad frequency band in a random fashion.‏​‏
答案: 【 frequency】

6、填空题：
‍For FHSS，the RF signal is （ ） at the receiver end using a frequency synthesizer controlled by‌‍a pseudorandom sequence generator synchronized to the transmitter’s pseudorandom‌‍sequence generator‌‍‌
答案: 【 dehopped】

7、填空题：
​CDMA requires synchronization among the users, since the waveforms are （ ） only if they are aligned in time‏​‏
答案: 【 orthogonal】

8、填空题：
‏In the DSSS, the spectrum of the transmitted signal is much wider than the spectrum associated with the （ ） rate‍‏‍
答案: 【 information##%_YZPRLFH_%##data】

9、填空题：
‍One of the advantages of the DSSS system is that the transmission bandwidth exceeds the coherence bandwidth. The received signal, after despreading, resolves into multiple signals with different ( )‍‍delays.‍