What are the technical indicators of communication? AB
A. Reliability B. Effectiveness C. Timeliness D. Wide coverage
What are the multiplexing techniques? ABCD
A. FDMA B. CDMA C. SDMA D. TDMA
The technique of using multiple frequencies to transmit signals is called spread spectrum technique. What is the purpose of this technique? AB
A. Anti-interference B. Improve security
C. Improve spectrum utilization D. Reduce delay
What are the main components of a LAN? AB
A. Wireless card B. Wireless bridge C. Router D. Hub
What are the topologies of WLANs? ABCD
A. Centerless topology B. Single access point approach
C. Multi-access point method D. Multi-cell roaming working method
6 Source coding is to reduce signal redundancy and improve effectiveness. right
7 (True or False) When the phase-frequency characteristic of the system is a slanted line passing through the origin, the system will produce serious intersymbol interference. wrong
8 (True or False) The access point of the wireless local area network is a necessary infrastructure. wrong
9 (True or False) RTS and CTS are mandatory in WLAN. wrong
10 (True or False) The WiMax technology uses the IEEE802.16 series of standards. right
11 (Fill in the blanks) A system with an operating frequency of 433.92MHz, a transmitting power of 26dBm, and a receiving sensitivity of -100dBm can travel a distance of 100km in free space . If the loss during the signal propagation is 25dB, then the actual communication distance is 6.3km . If the wireless communication distance is required to be 20km, at least 36dB of transmission power is required .
12(Fill in the blanks) As shown in the figure, in a local area network, A and B are communicating, and point C can communicate normally. Point E cannot communicate normally.
13(fill in the blank) The interference tolerance of the spread spectrum communication system is related to the system internal loss, processing gain and output signal-to-noise ratio .
14(Fill in the blank) A channel is a channel for transmitting signals . According to the fading model, channels are generally divided into large-scale fading and small-scale fading.
15 (fill in the blank) The IEEE802 reference model only uses the lowest two layers of the OSI reference model: physical layer and physical layer .
The working frequency band of Bluetooth devices is 2.4GHz , which uses frequency hopping technology to overcome interference and signal attenuation.
2 (Fill in the blank) In the IEEE802.15.4 standard protocol, it is stipulated that the data transmission rate of the 2.4G physical layer is 250 kbps.
3(fill in the blank) There can be 7 slave devices active in a bluetooth piconet.
4(Fill in the blank) IEEE802.11 protocol stipulates that there are 3 non-overlapping channels in 2.4G.
5(fill in the blank) The physical modules of Bluetooth include baseband, link manager and Bluetooth radio .
6(Fill in the blank) Bluetooth technology supports two kinds of physical connections: synchronous connection-oriented and asynchronous connectionless.
7(Fill in the blank) In the Bluetooth system, the establishment of a connection is divided into three steps: scanning, calling and querying.
8 (Single-choice question) Which of the following is not the technical feature of zigbee is B
A. Low complexity B. High power
C. Short range D. Low data rate
9(Single-choice question) The network topology that zigbee does not support is B
A. Star B. Ring C. Tree D. Mesh
10(Single-choice question) What reading mode does NFC technology adopt? active and passive
11(Single-choice question) Zigbee technology adopts protocol standard A
A. IEEE 802.15 B. 802.11 C. 802.12
12 (multiple choice) The frequency bands used by zigbee are A. 2.4G B. 915M C. 868M
13 (multiple choice) How many modes are there when the Bluetooth unit is connected?
A. Activate B. Hold C. Sleep D. Breathe
14(Multiple choice) Bluetooth protocol architecture is divided into
A. The underlying hardware module B. The core protocol layer C. The high-end application layer
15(Multiple choice) What constitutes the zigbee network ABC
A. One coordinator node B. Multiple routers
C. Multiple mid-end nodes D. Multiple coordinating nodes
16 (multiple choice) zigbee's network architecture includes BCD
A. Application Layer B. Network/Security Layer
C. Media Access Control Layer D. Physical Layer
17 (multiple choice) UWB technology is mainly used in ABCD
A. High-speed data transmission B. High-resolution radar system C. Positioning
D. Imaging systems that can penetrate walls, bodies, and floors
18(multiple choice) What working mode does NFC adopt? AD
A. Card mode B. Master-slave mode C. Decentralized mode D. Point-to-point mode
19 (Multiple choice) Regarding the pseudo-random sequence, the following description is correct BCD
A. PN sequences are random, they are non-deterministic, non-periodic sequences
B. The relative probability of 0 and 1 appearing is 1/2 each
C. The PN sequence is formed by combining the outputs of the feedback shift register
D. has autocorrelation properties
20 (multiple choice) Which of the following polynomials can be used as the primitive polynomial BC of the m-sequence generator with a period length of 7
A. 1+x B. 1+x^2+x^3 C. 1+x+x^3
Mobile communication is divided into AB according to the service area coverage method
A. Large district system B. Community system C. Strip D. Surface
2 (multiple choice) What are the characteristics of the increase in the number of clusters? AB
A. Low frequency utilization B. Small co-channel interference
C. High frequency utilization rate D. Large co-channel interference
3 (multiple choice) The first-generation communication system mainly adopts (analog) modulation method and (FDMA) multiple access method?
4 (Single-choice question) The second-generation communication system mainly adopts (digital) modulation.
5 (Single-choice question) Among the basic modulation methods of 2ASK, 2FSK and BPSK, (BPSK) has the best anti-interference performance
6 (multiple choice) What are the characteristics of GMSK modulation ABCD
A. Constant envelope B. Phase continuous
C. High spectrum utilization D. There is a phase jump point
7 (multiple choice) What are the main components of a modern communication network? ABCD
A. Terminals B. Channels C. Switching equipment D. Signaling and protocols
8 (Single-choice question) What kind of switching method is generally required for telephone service? A
A. Circuit switching B. Packet switching C. Message switching D. ATM
9 (Multiple choice) The logical channels of mobile communication are divided into: AB
A. Control channel B. Traffic channel C. Physical channel
10 (Multiple choice) The C-RAN network architecture adopted by 5G communication includes: ABC
A. Centralized processing B. Collaborative radio C. Real-time cloud computing architecture
11 (multiple choice) The essence of satellite communication is the combination of two technologies? AB
A. Microwave relay technology B. Space technology C. OFDM D. MiMO
12 (multiple choice) What parts does the satellite communication network include? ABCD
A. Earth station B. Space subsystem
C. Tracking telemetry and command subsystem D. Monitoring system
13(Fill in the blank) The network structure of 4G mobile communication can be roughly divided into three layers, which are the physical network layer, the intermediate environment layer and the application network layer
14(Fill in the blank) The GSM protocol is mainly for circuit switching services, while the GPRS protocol is for packet switching services. GPRS allows mobile users to occupy multiple time slots, but in GSM, mobile users generally only occupy one time slot.
15(Fill in the blanks) Circuit switching is to connect two user terminals to a dedicated channel through the exchange of the office station, so that they can communicate with each other until the communication ends, and only after the communication ends, the channel can be used by other user terminals . Packet switching decomposes a message into several data packets (packets) , each packet (packet) consists of a destination (destination) address, number and various control bits, etc. Switching point switching and switching.