EC-802-B Wireless Communication - May 2026 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
   aDiscuss the history and evolution of wireless services. Explain the technical and economic requirements that drive the development of modern wireless communication systems.
   How to answer

   • Brief history from Marconi to 1G/2G/3G/4G/5G and wireless services
   • Technical drivers: spectrum efficiency, coverage, data rate, mobility, QoS
   • Economic drivers: market demand, cost, competition, new services
   • Impact on modern system design
2. 7 Marks
   bExplain the architecture and implementation of Narrowband, Wideband, and Directional channel models used in modern wireless system simulations.
   How to answer

   • Definition of narrowband, wideband and directional channel models
   • Architecture / mathematical structure of each model
   • Implementation approach for system simulation
   • Use cases in modern wireless simulations
3. 7 Marks
   aCompare the performance of various digital modulation formats (BPSK, QPSK, QAM) in terms of spectral efficiency, power efficiency, and suitability for fading channels.
   How to answer

   • Signal constellation and spectral efficiency of BPSK, QPSK, QAM
   • Power efficiency / BER vs SNR comparison
   • Behaviour under fading and need for equalization/coding
   • Suitability summary table
4. 7 Marks
   bWhat are Ultra-Wideband (UWB) channels? Discuss their characteristics and contrast them with conventional narrowband directional channel descriptions.
   How to answer

   • Definition and bandwidth / power characteristics of UWB
   • Key channel characteristics: multipath resolution, low power, coexistence
   • Conventional narrowband directional channel description
   • Contrast table: bandwidth, fading, angular dependence
5. 7 Marks
   aWhat is Channel Sounding? Explain the time-domain channel sounding technique using a block diagram and discuss its limitations.
   How to answer

   • Definition of channel sounding and its purpose
   • Block diagram of time-domain sounder: PN sequence, transmitter, receiver
   • Operation and impulse response measurement principle
   • Limitations: noise, synchronization, time resolution
6. 7 Marks
   bDefine Diversity in wireless communication. Differentiate between Microdiversity, Macrodiversity, and Simulcast. Explain how diversity improves system reliability.
   How to answer

   • Definition of diversity in wireless communication
   • Microdiversity vs macrodiversity vs simulcast differences
   • Mechanisms: space, time, frequency, polarization diversity
   • How diversity combats fading and improves reliability
7. 7 Marks
   aWhat is Doppler Shift? Derive the Doppler spectrum and explain how the temporal dependence of fading is related to the velocity of the mobile receiver.
   How to answer

   • Definition of Doppler shift due to mobile motion
   • Derivation of Doppler spectrum / Clarke-Jakes spectrum
   • Relation of Doppler spread and coherence time to velocity
   • Effect on temporal fading rate
8. 7 Marks
   bEvaluate and compare the error probability performance of digital modulation schemes when operating in flat-fading channels versus AWGN channels.
   How to answer

   • Error probability in AWGN: Q-function dependence on SNR
   • Averaging over fading statistics in flat-fading channels
   • Performance degradation and error floors in fading
   • Comparative curves and conclusions
9. 7 Marks
   aWhat is Transmit Diversity? Explain Alamouti's space-time block coding (STBC) scheme and its significance in modern MIMO wireless systems.
   How to answer

   • Concept of transmit diversity vs receive diversity
   • Alamouti 2x1 STBC encoding matrix and decoding
   • Diversity order and simple linear combining
   • Significance for MIMO and modern standards
10. 7 Marks
    bExplain the phenomenon of multipath propagation. How does it lead to noise and interference-limited systems in wireless environments?
    How to answer

    • Multipath propagation: reflection, diffraction, scattering paths
    • Constructive/destructive superposition and fading
    • Noise-limited vs interference-limited regimes
    • Impact on capacity and system design
11. 7 Marks
    aDifferentiate between Reflection, Diffraction, and Scattering as propagation mechanisms. Explain wave guiding and how rough surfaces affect wave scattering.
    How to answer

    • Definitions of reflection, diffraction, scattering
    • Comparison of conditions and propagation effects
    • Waveguiding in urban / indoor environments
    • Effect of rough surfaces using Rayleigh criterion
12. 7 Marks
    bDescribe the Frequency Domain Analysis method for channel sounding. Compare its advantages and disadvantages over time-domain measurement techniques.
    How to answer

    • Principle of frequency-domain sounding using VNA / swept frequency
    • Measurement procedure and IFFT to obtain impulse response
    • Advantages: accuracy, dynamic range, calibration
    • Disadvantages vs time-domain: non-real-time, cost, time variance
13. 7 Marks
    aDefine the Wide-Sense Stationary Uncorrelated Scattering (WSSUS) model. Discuss its importance in describing the system-theoretic aspects of wireless channels.
    How to answer

    • Definition of WSS and US assumptions forming WSSUS
    • Mathematical correlation functions
    • System-theoretic channel functions and Bello functions
    • Importance for characterizing dispersive fading channels
14. 7 Marks
    bDescribe the statistical behavior of wireless channels. Differentiate between time-invariant and time-variant two-path models with suitable mathematical representations.
    How to answer

    • Statistical description: Rayleigh, Ricean, Nakagami fading
    • Time-invariant two-path model equation
    • Time-variant two-path model with Doppler terms
    • Comparison of impulse responses and implications
15. 14 Marks
    Write short notes on any **two** of the followings.

    1. (i))Antenna for Mobile Stations.
    2. (ii))Fractional spaced equalizer.
    3. (iii))TDMA and CDMA Systems
    How to answer

    • Principle, types and key features of chosen topics
    • Block diagram / structure and operation
    • Advantages, limitations and applications in wireless systems
    • Concluding comparison or summary