EC-802-B Wireless Communications - May 2022 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWrite an introductory note on wireless communication and its services.
   How to answer

   • Definition of wireless communication and evolution
   • Types of services: voice, data, multimedia, broadcasting
   • Examples: cellular, WLAN, satellite, paging
2. 7 Marks
   bElaborate different requirements for the wireless services in economic and social aspects.
   How to answer

   • Economic requirements: cost, spectrum efficiency, market demand
   • Social requirements: mobility, connectivity, emergency services
   • Quality, coverage and affordability aspects
3. 7 Marks
   aExplain different technical challenges in wireless communication. Discuss all those point in brief.
   How to answer

   • Limited spectrum, interference and fading
   • Multipath propagation, Doppler and mobility
   • Power, security and network complexity challenges
4. 7 Marks
   bWhat do you mean by reflection and transmission in wireless communication?
   How to answer

   • Definition of reflection with Snell's law
   • Definition of transmission through medium
   • Effect on propagation and examples
5. 7 Marks
   aClassify different causes of delay dispersion in directional channel. Write its remedial also.
   How to answer

   • Causes of delay dispersion: multipath, reflection, scattering
   • Directional channel specific causes
   • Remedial techniques: equalization, diversity, OFDM
6. 7 Marks
   bDraw and explain the WSSUS model. Describe the condensed parameters.
   How to answer

   • WSSUS assumption: WSS in time and US in delay
   • Block diagram of WSSUS model
   • Condensed parameters: delay spread, Doppler spread, coherence bandwidth/time
7. 7 Marks
   aExplain the narrowband, wideband and directional models. Also, discuss about the deterministic channel modeling methods.
   How to answer

   • Narrowband vs wideband vs directional model definitions
   • Deterministic modeling: ray tracing, FDTD
   • Comparison of assumptions and applications
8. 7 Marks
   bGive a brief introduction on Channel sounding. Discuss about the time domain measurement.
   How to answer

   • Definition and purpose of channel sounding
   • Time-domain measurement principle using PN pulse
   • Block diagram and measured impulse response
9. 7 Marks
   aSketch the structure of a wireless communication link and explain its characteristics.
   How to answer

   • Block diagram of transmitter-channel-receiver link
   • Components: antennas, propagation channel, noise
   • Characteristics: path loss, fading, interference
10. 7 Marks
    bDiscuss about the AWGN models. Discuss about the error probability in AWGN channels.
    How to answer

    • AWGN model definition and statistics
    • Error probability expression for BPSK/QAM in AWGN
    • Effect of SNR on BER with formula/curve
11. 7 Marks
    aGive a brief introduction on diversity in wireless communication.
    How to answer

    • Definition and need for diversity
    • Types: time, frequency, space, polarization
    • Diversity gain and combining methods
12. 7 Marks
    bWrite any five differences between Micro diversity and Macro diversity.
    How to answer

    • Definition of micro vs macro diversity
    • Five differences: scale, fading type, antenna separation, purpose
    • Examples of each in tabular form
13. 7 Marks
    aWhy equalizers are important in wireless devices? Give a brief classification of equalizers used in wireless communication system.
    How to answer

    • Role of equalizers against ISI
    • Classification: linear, DFE, MLSE, blind, adaptive
    • Applications in wireless devices
14. 7 Marks
    bGive a brief comparison of equalizer structures with suitable examples.
    How to answer

    • Structures: linear, DFE, MLSE/Viterbi, fractionally spaced
    • Comparison on complexity, performance, ISI handling
    • Suitable examples for each structure
15. 14 Marks
    Write short note (any four)

    1. i)Fading channels
    2. ii)Blind equalizers
    3. iii)Viterbi detector
    4. iv)Fractional spaced equalizer
    5. v)Doppler spectra
    How to answer

    • Brief definition of any four selected topics
    • Key principle/diagram/formula for each
    • Applications and advantages/limitations