EC-703-A Cellular Mobile Communication - Jun 2025 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 about the basic principle operation of cellular systems.
   How to answer

   • Define cellular concept with frequency reuse and cell splitting
   • Explain basic elements: cell, cluster, base station, MSC
   • Describe operation: call setup, handoff, channel assignment
   • Mention capacity improvement by reuse
2. 7 Marks
   bDetermine the desired C/I in an Omni-directional antenna system.
   How to answer

   • Define C/I ratio for cellular system
   • Write co-channel interference expression for omni-directional case with 6 interferers
   • Relate C/I to cluster size N and path-loss exponent
   • Determine desired value for acceptable voice quality
3. 7 Marks
   aExplain about the co channel interference reduction factor.
   How to answer

   • Define co-channel interference and reuse distance
   • Define co-channel interference reduction factor q = D/R
   • Explain relation q = sqrt(3N)
   • Explain effect on capacity and C/I
4. 7 Marks
   bCalculate the change in received signal power (in decibels) in mobile radio propagation condition at two different distance points when the second distance point is twice the distance from the first point.
   How to answer

   • State mobile radio path-loss law Pr proportional to d^-gamma
   • Take ratio for d2 = 2*d1 in dB: delta = -gamma*10*log10(2)
   • Evaluate for typical gamma = 4 (~ -12 dB) and gamma = 2 (~ -6 dB)
   • Conclude power decreases when distance doubles
5. 7 Marks
   aExplain the propagation over water in mobile communication.
   How to answer

   • Describe reflection from water surface and two-ray model
   • Explain effect of smooth surface, tidal variation and roughness
   • Discuss path loss and fading over water
   • Mention practical considerations for mobile communication
6. 7 Marks
   bExplain the principle of mobile to mobile propagation.
   How to answer

   • Define mobile-to-mobile channel with both ends in motion
   • Explain double Doppler and multipath scattering
   • Describe statistical model and fading characteristics
   • Contrast with base-to-mobile propagation
7. 7 Marks
   aDiscuss about the cell site antenna heights and signal coverage cells.
   How to answer

   • Explain role of base-station antenna height in coverage
   • Discuss trade-off: high antenna vs interference and low antenna vs holes
   • Describe signal coverage cell types and shaping
   • Mention down-tilting and power control
8. 7 Marks
   bExplain about the gain and pattern relationship of antenna.
   How to answer

   • Define antenna gain and directivity
   • Explain relation between gain, beamwidth and radiation pattern
   • Describe omni vs directional patterns
   • Explain impact on coverage and interference
9. 14 Marks
   Design a system to serve a predefined area that experiences co channel interference.
   How to answer

   • Identify co-channel interference problem in predefined area
   • Select cluster size and reuse plan to meet C/I
   • Apply sectorization / channel assignment / power control
   • Verify coverage and C/I performance
10. 7 Marks
    aExplain about the fixed channel assignment algorithm.
    How to answer

    • Define fixed channel assignment concept
    • List steps of FCA algorithm: allocation, borrowing, blocking
    • Explain call setup and release procedure
    • Mention advantages and limitations vs dynamic assignment
11. 7 Marks
    bClassify handoff based on nature of handoff and Explain.
    How to answer

    • Define handoff and need for handoff
    • Classify by nature: hard, soft, softer, intra/inter-system
    • Explain each type with example
    • Compare signaling and call continuity
12. 7 Marks
    aExplain the architecture and working of GSM system.
    How to answer

    • Draw GSM architecture: MS, BTS, BSC, MSC, HLR/VLR
    • Explain function of each subsystem
    • Describe call flow and signaling
    • Mention TDMA frame and services
13. 7 Marks
    bExplain about the call processing and hand off procedure in CDMA system.
    How to answer

    • Outline CDMA call processing: origination, paging, access
    • Explain power control and Walsh/PN codes
    • Describe soft/softer handoff procedure steps
    • Mention rake receiver role in handoff
14. 14 Marks
    Write short notes on any two of the following.

    1. i)Mobile point to point model
    2. ii)Umbrella pattern effect
    3. iii)Frequency spectrum utilization
    How to answer

    • Select any two topics from i/ii/iii
    • Give definition and key principle for each
    • Explain relevance with diagram/example
    • Conclude with applications/limitations