Each of the signal when it receives are mixed. 1, 2 and 3 are correct b. If user has equal power and the desired level of performance of an error probability of 10-6, the number of user will be, To achieve an error probability of 10-6 ,we required, Then, the number of users of the CDMA system is, In previous question if processing gain is changed to 500, then number of users will be, If the processing gain is reduced to W/R = 500, then. On the other hand, primary objective of all the modulation schemes is to minimize the required transmission bandwidth. The receiver cannot "see" the transmission without the right spread-spectrum keys. What is PN sequence? 3. 74. Explanation: Advantages of spread spectrum are low susceptibility, reduced interference, immunity to jamming and co existence of multi path system. In spread spectrum the information signal is modulated by a wideband pseudo-noise (PN) signal, resulting in a much larger transmit signal bandwidth than in the original signal. 131) The advantages of using a CDMA technique over other spread spectrum techniques are. Each state of the shift register selects one of L non over lapping frequency bands in the hopping pattern. The carrier of the direct-sequence radio stays at a ___ frequency. Spread spectrum is a technique used for wireless communications in telecommunication and radio communication. (b) The broadcast control channel (BCCH) Link to download pdf form a) Centralized spectrum sharing does not rely on fixed infrastructure units b) Centralized spectrum sharing holds … Spread Spectrum allocates disjoint resources (frequency or time slots depending on the access system) to each user. To received signals for the GPS system from the four satellites, compute the distance differences, and determine position . A spread spectrum communications system is one that is built upon the principle of transmitting information signals over a much wider bandwidth than is strictly necessary for transferring the information. Same spectrum and different PN code c. Different spectrum and different PN code d. Different spectrum and same PN code. 2. 18. Study these Interview MCQ Questions and Answers on 3G UMTS WCDMA network Architecture and Interfaces. This set of Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) focuses on “Spread Spectrum Modulation Techniques”. Que: The processing gain of the system is, The period of the maximum length shift register sequence is. Q9. Pseudo noise sequence is a coded sequence of 1’s and 0’s with autocorrelation properties. Spread spectrum signals are subject to the same jamming equations as any other signals, but the ability of the cooperative receiver to collapse the spectrum gives it a "processing gain" that reduces the effectiveness of the jamming. Computer Networks Notes and Technology Articles, Download eBooks for Computer Science Degree, Cellular Telephone and Satellite Networks MCQs, Computer Architecture Questions and Answers, Introduction to Computer Performance Quiz, Computer Network and Data Communications Quizzes and Tests, bandwidth utilization: multiplexing and spreading Multiple Choice Questions and Answers (MCQs), Frame Relay in VCN Multiple Choice Questions (MCQs), Internet Checksum Multiple Choice Questions (MCQs), Computer Networks MCQs: Multiple Choice Questions and Answers (Quiz & Tests with Answer Keys), online bandwidth utilization multiplexing and spreading tutorial, A pseudorandom code generator that creates a. Ranging: b. The advantage of using SDMA over other spread spectrum technique is a. Direct RF pulse system 2. Spread Spectrum Multiple Choice Questions (MCQ), spread spectrum quiz answers PDF to practice online networking test for online classes. c) Different spectrum and different pn code. An eavesdropper would not know a signal was being sent. The signal occupies a bandwidth much greater than that which is necessary to send the information . An m =10 ML shift register is used to generate the pre hdarandlm sequence in a DS spread spectrum system. Ans. Que: The processing gain of this system is. When … Q8. Mobile station battery consumption is low ... Q3. The jammer power is 20 dB greater then the desired signal, and the required εb/J0 to achieve satisfactory performance is 10 dB. UMTS network is called a Third Generation Network(3G). Spread spectrum signals are used for Ranging Determination of position Ranging & Determination of position None of the mentioned. In this technique, the frequency of the transmitted signal, i.e., an electrical signal, electromagnetic signal, or acoustic signal, is deliberately varied and generates a much greater bandwidth than the signal would have if its frequency were not varied. Since there are N = 2767 states of the shift register and for each state we select one of two frequencies separated by 400 Hz, the hopping bandwidth is 13.1068 MHz. Que: The spreading bandwidth required to meet the specifications is, We have a system where  (Jav/Pav) = 20 dB, R =1000, and (εb/J0)db = 10 dB. Que: If the jammer operates as a partial band jammar, the bandwidth occupancy for worst case jamming is, The bandwidth of the worst partial-band jammer is α * W , where, Que: The probability of error for the worst-case partial band jammer is, The probability of error with worst-case partial-band jamming is, Que: The minimum hop rate for a FH spread spectrum system that will prevent a jammer from operating five onives away from the receiver is. Que: How much should the processing gain be increased to allow for doubling the number of users with affecting the autopad SNR. b) Fsk. 11-40 shows a standard narrowband signal and a spread spectrum signal. Fig. Clarification: Spread spectrum techniques employ a transmission bandwidth that is several orders of magnitude greater than the minimum required signal bandwidth. These narrowband signals are easily jammed by any other signal in the same band. Digital Communication Objective type Questions and Answers. The modulation scheme is BPSK. Spread Spectrum uses ___ noise-like signals. The probability of a chip error with non-coherent detection is, In a fast FH spread spectrum system, the information is transmitted via FSK with non coherent detection. Which among the following is true about centralized spectrum sharing? 2, 3 and 4 are correct c. 1, 2 and 4 are correct d. All the four are correct. GSM uses a TCH to transmit user data. Both the Narrow band and Spread spectrum signals can be understood easily by observing their a. Why is autocorrelation used to receive direct-sequence spread-spectrum signals? a) dpsk. d) Different spectrum and same pn code . Spread Spectrum refers to a system originally developed for military applications, to provide secure communications by spreading the signal over a large frequency band. Noise developed at the receiver b. If we use BPSK with its 1 bit/Hz effi ciency, we could transmit this signal in a bandwidth of about 13 kHz. Here an object can use signals from several satellites transmitting SS signals according to a predefined format to determine its own position accurately on the globe. Frequency-hopping spread spectrum is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. Spread spectrum involves stretching a signal over a bandwidth which is wider than its original bandwidth. 297. A. A. FDM . One can, for example, use spread-spectrum techniques to transmit a signal modulated by FSK or BPSK. 5.4. All rights reserved. 5.9 Jamming Spread Spectrum Signals. ANSWER: 1, 2 and 3 are correct. pseudo-noise codes. UMTS works on WCDMA, CDMA2000 and TD-SCDMA implementations by 3GPP. Q7. The channel is AWGN with power spectral density 1/2 N0 and an SNR 20-13 dB (total SNR over the three hops), Que: In case of one hop per bit the probability of error is. In general, Spread Spectrum communications is distinguished by which of these elements? 3. d) Qpsk . PDF | On Apr 2, 2013, mahendra Kumar published multiple choice questions on wireless communication | Find, read and cite all the research you need on ResearchGate Spread spectrum generally makes use of a sequential noise -like signal structure to spread the normally narrowband information signal over a relatively wideband (radio) band of frequencies. 254. The receiver correlates the received signals to retrieve the original information signal. A slow FH binary FSK system with non coherent detection operates at ε0/J0 10, with hopping bandwidth of 2 GHz, and a bit rate of 10 kbps. The demodulator employ non coherent detection. Since the shift register has L = 32767 states and each state utilizes a bandwidth of 2/T = 200 Hz, then the total bandwidth for the FH signal is 6.5534 MHz. Suppose there are N = 3 hops/bit with hard decision decoding of the signal in each hop. Therefore the SNR per hop is 20/3. (a) Traffic channels (TCH) (b) Broadcast control channel (BCCH) (c) Common control channel (CCCH) (d) Dedicated control channel (DCCH) Ans. Multiple user access 4. Que: If the hop rate is one per bit, the hopping band width for this channel is, The length of the shift-register sequence is. The DS spread spectrum sequence has a chip rate of 10 MHz, A CDMA system is designed based on DS spread spectrum with a processing gain of 1000 and BPSK modulation scheme. This mock test of Spread Spectrum - MCQ Test for Electronics and Communication Engineering (ECE) helps you for every Electronics and Communication Engineering (ECE) entrance exam. A DS spread spectrum system transmit at a rate of 1 kbps in the presets of a tone jammer. Fast hopping is b) Same spectrum and different pn code. c. Spatial separation . Clarification: Underlay spectrum sharing technique employs spread spectrum techniques while transmitting in the licensed portion of the spectrum band. Determination of position: c. Ranging & Determination of position: d. None of the mentioned The use of ___ in spread spectrum communications makes signals appear wideband and noise-like. (True/False) Ans. a. Therefore bandwidth utilization and interference towards the primary user is increased. Answer: During transmission, the PN sequences determine which parts of the available bandwidth the spread spectrum signal will occupy. So far, three main methods are available. Spread spectrum generally makes use of a sequential noise-like signal structure to spread the normally narrowband information signal over a relatively wideband (radio) band of frequencies. 1. A receiver, which does not know the sequence, cannot demodulate the signal. Processing gain is the ratio of message bandwidth to signal bandwidth. You can find other Spread Spectrum - MCQ Test extra questions, Spread-spectrum signal is buried under the noise level. The changes are controlled by a code known to both transmitter and receiver. … a. Direct RF pulse system 2. C. TDM . Frequency domain channel sounding Ans. 16. Ans. This contains 20 Multiple Choice Questions for Electronics and Communication Engineering (ECE) Spread Spectrum - MCQ Test (mcq) to study with solutions a complete question bank. This mock test of Spread Spectrum - MCQ Test for Electronics and Communication Engineering (ECE) helps you for every Electronics and Communication Engineering (ECE) entrance exam. The spreading code used in this example was only four bits long. d. Spread spectrum For binary FSK modulation, the minimum frequency separation is 2/T, where 1/T is the symbol (bit) rate. Spread spectrum multiple access uses signals which have a transmission bandwidth whose magnitude is greater than the minimum required RF bandwidth. Que: If the required εb /J0 is 10 and the jammer is a tone jammer with an average power Jav, then jamming margin is. B. And without knowing the exact sequence being used, it is virtually impossible to "de-spread" the signal. The advantages of spectrum spreading include noise reduction, security and resistance to jamming and interception. The receiver correlates the received signals to retrieve the original information signal. students definitely take this Spread Spectrum - MCQ Test exercise for a better result in the exam. The spread of energy over a wide band, or lower spectral power … Practice for BBA or MBA exams using these MCQ. Since spread-spectrum signals are so wide, they transmit at a much lower spectral power density, measured in watts per hertz, than narrow band transmitters. 6. B. ATM . Direct sequence spread spectrum demodulation uses. The user segment is used to received signals for the GPS system from the four satellites, compute the time differences, and determine position, while space segment’s function is(are) a. 317. Each state of the shift register selects one of L non over lapping frequency bands in the hopping pattern. WLAN: Wireless LAN (Local Area Networks) widely use spread spectrum communications. Advertisement. A directory of Objective Type Questions covering all the Computer Science subjects. The satellite frequency reuse method which sends different information signals using vertical or horizontal electromagnetic polarization. Therefore bandwidth utilization and interference towards the primary user is increased. It uses a narrow band frequency B. 17. We are given a hopping bandwidth of 2 GHz and a bit rate of 10 kbs. To transmit time codes and orbital position information to the users 19. In spread spectrum technique, the multiple users are assigned. If the hopping rate is 2 hops/bit and the bit rate is 100 bits/sec, then, the hop rate is 200 hops/sec. D. Spread spectrum This would have appeared as noise in the system. Digital Communication Objective type Questions and Answers. In spread spectrum technique, the multiple users are assigned with. The chip duration is Tc = ℓμs  and the bit duration is Tb, = NTc, where N is the length (period of the m sequence). By continuing, I agree that I am at least 13 years old and have read and agree to the. Figure 1 represents a narrow band signal in the frequency domain. EduRev is a knowledge-sharing community that depends on everyone being able to pitch in when they know something. 5. b. Dual polarization . long questions & short questions for Electronics and Communication Engineering (ECE) on EduRev as well by searching above. A DS spread spectrum system transmit at a rate of 1 kbps in the presets of a tone jammer. Spread spectrum signals are used for Ranging Determination of position Ranging & Determination of position None of the mentioned. In the given example, the spread signal of the user A at the code A, and diffused signal of user B at code B. Suppose there are N = 3 hops/bit with hard decision decoding of the signal in each hop. 36) The techniques used for small scale multipath measurements are 1. A pseudo noise (PN) sequence converts a narrowband signal to a wideband noise like signal before transmission 5.3. Node-station links are generally dedicated ___ links. The minimum frequency separation for orthogonality 2/T =400 Hz. This capability is the main attraction for all the interest in spread spectrum today. Resistance to Fading (Multipath Effects) Wireless channels often include multiple-path propagation in which the signal has more than one path from the transmitter to the receiver (Figure 7). Learn bandwidth utilization: multiplexing and spreading Multiple Choice Questions and Answers (MCQs), "Spread Spectrum" quiz questions and answers for information and communication technology. This contains 20 Multiple Choice Questions for Electronics and Communication Engineering (ECE) Spread Spectrum - MCQ Test (mcq) to study with solutions a complete question bank.
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