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    NPTEL Online Certification Courses Indian Institute of Technology Kharagpur

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    NPTEL Online Certification Courses Indian Institute of Technology Kharagpur

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    Detailed solutions and references to online course lectures are provided for each question to

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    5g week 1

    Original Title

    5G W1

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    Detailed solutions and references to online course lectures are provided for each question to

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    Download as pdf or txt
    168 views7 pages

    NPTEL Online Certification Courses Indian Institute of Technology Kharagpur

    Uploaded by

    ece gptplpt
    Detailed solutions and references to online course lectures are provided for each question to

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    © All Rights Reserved
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    Download as pdf or txt
    of 7

    NPTEL Online Certification Courses

    Indian Institute of Technology Kharagpur

    Evolution of Air Interface towards 5G


    Assignment- 1
    TYPE OF QUESTION: MCQ/MSQ
    Number of questions: 15 Total marks: 15 X 1 = 15
    ______________________________________________________________________________
    QUESTION 1:
    The data rates offered by GSM (2G) system
    a. Few kbps
    b. Few Mbps
    c. Few Gbps
    d. 10 Gbps
    Correct Answer: (a)

    Detailed Solution:

    Refer to lecture 2, 1:50 for detailed discussion on the topic.

    QUESTION 2:
    Which of the following modulation formats is used in EDGE for high data rates?
    a. GMSK
    b. 8-FSK
    c. 8-PSK
    d. 16-QAM
    Correct Answer: (c)

    Detailed solution

    Refer to lecture 2, 17:18 min for detailed discussion on the topic.

    QUESTION 3:
    The advantage of having lower Peak to Average Power Ratio (PAPR) in a modulation format:
    a. Power Amplifier can be operated at its higher efficiency
    b. A lower transmission bandwidth
    c. Noise power level in receiver can be reduced
    d. Helps smooth phase transition
    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    Correct Answer: (a)

    Detailed solution:

    Refer to lecture 2, 18:00-19:00, GMSK and its advantages and usage in 2G standard for detailed
    discussion of the topic

    QUESTION 4:
    The Hybrid ARQ technique is first introduced in
    a. 2G
    b. 3G
    c. 3.5G
    d. 4G

    Correct Answer: (c)

    Detailed Solution:

    Refer to lecture 3, around 4:00 min. for detailed discussion on the topic.

    _____________________________________________________________________________

    QUESTION 5:
    What is the Channel bandwidth for WCDMA systems?
    a. 200 kHz
    b. 1.25M Hz
    c. 1.4 MHz
    d. 5 MHz

    Correct Answer: (d)

    Detailed solution:

    Refer to lecture 3, 10:20 min. for detailed discussion on the topic.

    ___________________________________________________________________________

    QUESTION 6:
    The minimum transmit time interval (TTI) specified for 3GPP LTE is

    a. 1 µs
    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    b. 10 µs
    c. 1 ms
    d. 10 ms

    Correct Answer: (c)

    Detailed Solution:

    Refer to lecture 4, 23:00 min. for detailed discussion on the topic.

    __________________________________________________________________________

    QUESTION 7:
    In a 10-cell WCDMA system, 1000 active users are present and each user has received 50 number of bits
    correctly on an average over 1 milli second interval of time. Find the cell spectral efficiency for the
    channel bandwidth of 5 MHz.
    a. 1 bit/s/Hz/cell
    b. 1.5 bit/s/Hz/cell
    c. 2 bit/s/Hz/cell
    d. 2.5 bit/s/Hz/cell
    Correct Answer: (a)

    Detailed Solution:

    Total Number of users N=1000, Number of cells M=10, Time over which data bits are received T= 10-3
    sec, Number of correctly received bits by user i 𝜒𝑖 = 50, Channel bandwidth ω= 5x106 Hz. Substituting
    these values in the following equation

    ∑𝑁 𝜒
    𝑖=1 𝑖 1000×50
    The cell spectral efficiency 𝜂 = 𝑇×𝜔×𝑀 = 10−3 ×5×106 ×10= 1 bit/s/Hz

    __________________________________________________________________________

    QUESTION 8:
    Find the normalized user throughput for a user in uplink if 150 bits are transmitted correctly by the user
    over an active session of 2 milli second using a channel bandwidth of 5 MHz.
    a. 0.015 bit/s/Hz
    b. 0.025 bit/s/Hz
    c. 0.035 bit/s/Hz
    d. 0.045 bit/s/Hz
    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    Correct Answer: (a)

    Detailed solution
    𝜒
    𝑖
    𝛾𝑖 = 𝑇 ×𝜔
    𝑖

    Given 𝜒𝑖 = 150 bits, 𝑇𝑖 = 2x10-3 seconds, and 𝜔 = 5 MHz.


    150
    Then the normalized user throughput: 𝛾𝑖 = = 0.015 bit/s/Hz
    2×10−3 ×5×106

    __________________________________________________________________________

    QUESTION 9:
    Among the following, which is/are the newly developed tools for providing improved service in
    upcoming 5G mobile standard?

    a. Beamforming using Massive MIMO


    b. Use of small cell
    c. Use of OFDM
    d. Use of high frequency bandwidths (mmWave)

    Correct Answer: (a), (b), (d)

    Detailed solution

    Refer to 24:01 of lecture 5 where important tools are discussed. OFDM has already been implemented in
    4G LTE.

    _________________________________________________________________________

    QUESTION 10:
    Among the following, which one is NOT a main component of the fourth generation (4G) mobile
    networks?

    a. Higher order modulation


    b. Use of OFDM
    c. Use of multiple antenna
    d. Use of spreading codes for inter-user interference cancellation

    Correct Answer: (d)

    Detailed solution

    Spreading codes is predominantly used in 3G standard of mobile communication. All the other three
    options are used in 4G. Refer to lecture 4, 21:00 min for details.
    ____________________________________________________________________________
    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    QUESTION 11:
    The downlink spectral efficiency of a cell is given to be 10 bit/s/Hz and if there are 20 active users are
    associated with the base station, find the data rate per user when the channel bandwidth is 10 MHz.
    a. 2 Mbps
    b. 3 Mbps
    c. 4 Mbps
    d. 5 Mbps
    Correct Answer: (d)

    Detailed Solution

    The total data rate the cell can support in downlink (R) = the downlink spectral efficiency×Channel
    bandwidth
    R = 10 bit/s/Hz × 10 MHz = 100 Mbs
    Per user data rate = total data rate (R) ÷ the number of users = 100 Mbps/20 = 5Mbps

    _____________________________________________________________________

    QUESTION 12:
    Among the following, which technologies will be potentially used to realize the huge demand of
    throughput and high-quality services specified in 5G ?

    a. Use of GMSK
    b. Reduction in cell size
    c. Use of Massive MIMO
    d. All of the above

    Correct Answer: (b) and (c)

    Detailed Solution:

    Refer to lecture 5, 24:00 min. onwards for detailed discussion on the topic.

    _____________________________________________________________________

    QUESTION 13:
    The LTE Advanced achieved 30 bps/Hz spectral efficiency in downlink by multiplexing
    a. 6 spatial data streams
    b. 7 spatial data streams
    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    c. 8 spatial data streams


    d. 10 spatial data streams

    Correct Answer: (c)


    Detailed Solution:

    Refer to Lecture 5, 4:00 min for detailed discussion on the topic

    _____________________________________________________________________

    QUESTION 14:
    What is the minimum percentage of packets that should be delivered to a VOIP user successfully with a
    delay bound of 50% so that the user does not experience outage?
    a. 90%
    b. 95%
    c. 98%
    d. 99%
    Correct Answer: (c)

    Detailed solution

    Refer to Lecture 4, 16:50 min. for detailed discussion on the topic.

    _____________________________________________________________________

    QUESTION 15:
    Classify the following keywords related to GSM and WCDMA standards of mobile
    communication:
    Packet scheduling; Frequency reuse >1; Bandwidth=200 KHz; Rake receiver.

    a. GSM:- Packet scheduling, Frequency reuse >1;


    WCDMA:- Bandwidth=200 KHz, Rake receiver.

    b. GSM:- Bandwidth=200 KHz, Rake receiver;


    WCDMA:- Packet scheduling, Frequency reuse >1.

    c. GSM:- Bandwidth=200 KHz, Frequency reuse >1;


    WCDMA- Rake receiver, Packet scheduling.

    d. GSM- Rake receiver, Packet scheduling;


    NPTEL Online Certification Courses
    Indian Institute of Technology Kharagpur

    WCDMA- Bandwidth=200 KHz, Frequency reuse ≥1.

    Correct Answer: (c)

    Detailed solution

    Refer to lecture 3, 13:22 min. for detailed discussion on the topic.

    ************END*********

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