Mobile Communication MCQ QUESTIONS AND ANSWERS
## 🟢 Unit I – Mobile Radio Propagation (20 MCQs)
1. Scattering refers to:
A) Reflection off smooth surface
B) Redirection by rough objects
C) Bending around edges
D) Absorption by atmosphere
**Answer: B**
2. Reflection, diffraction and scattering are mechanisms of:
A) Small-scale fading
B) Propagation
C) Channel coding
D) Modulation
**Answer: B**
3. Free-space path loss increases with:
A) Distance squared
B) Inverse distance
C) Constant
D) Frequency decrease
**Answer: A**
4. The two‑ray model accounts for:
A) Direct and reflected rays
B) Scattering only
C) Diffraction only
D) Antenna imperfections
**Answer: A**
5. Small-scale fading results from:
A) Distance change only
B) Multipath interference
C) Fixed attenuation
D) Static obstacles
**Answer: B**
6. Large‑scale path loss describes:
A) Fading in milliseconds
B) Slow average power drop with distance
C) Random amplitude fluctuation
D) Terrain-dependent diffraction only
**Answer: B**
7. The two‑ray model predicts signal nulls when:
A) Antenna height changes
B) Path difference = multiple of wavelength/2
C) Perfect reflection occurs
D) Using omnidirectional antennas
**Answer: B**
8. Diffraction occurs when waves:
A) Reflect off surfaces
B) Bend around obstacles
C) Scatter randomly
D) Travel in free space
**Answer: B**
9. In two-ray, if antenna heights double, interference pattern:
A) Remains same
B) Spacing increases
C) Spacing decreases
D) Disappears
**Answer: C**
10. Small-scale fading includes:
A) Large obstacles only
B) Ground reflections only
C) Delay spreads and multipath
D) Hexagonal cells
**Answer: C**
11. Reflection causes:
A) Phase shift and amplitude change
B) Frequency shift only
C) No phase effect
D) Only scattering
**Answer: A**
12. Free space path loss ∝ (4πd/λ)²; more loss at:
A) Lower frequency
B) Shorter distances
C) Higher frequency
D) Larger wavelength
**Answer: C**
13. Two-ray model is used above:
A) Sea and flat terrain
B) Urban clutter
C) Dense forest
D) Only indoors
**Answer: A**
14. Small-scale fading timescale:
A) Seconds
B) Minutes
C) Milliseconds
D) Hours
**Answer: C**
15. Shadow fading involves:
A) Signal roll-off due to unwanted motion
B) Slow variations from terrain
C) Fast fading peaks
D) No amplitude change
**Answer: B**
16. Multipath spread causes:
A) Frequency reuse
B) Time dispersion and ISI
C) Antenna misalignment
D) Skyline limitation
**Answer: B**
17. In two‑ray, as distance increases, path difference:
A) Constant
B) Increases causing periodic fading
C) Decreases
D) Zero beyond horizon
**Answer: B**
18. Scattering dominates at:
A) Low frequencies
B) High frequencies and small obstacles
C) Open terrain only
D) Uniform media
**Answer: B**
19. Small‑scale fading can be mitigated by:
A) Larger cells
B) Diversity or equalization
C) Higher TX power only
D) Slower user speed
**Answer: B**
20. Two-ray model is valid if TX and RX height >:
A) Several λ
B) Zero
C) MHz
D) Antenna gain
**Answer: A**
---
## 🟢 Unit II – Cellular Concepts & Handoff Strategies (20 MCQs)
21. Frequency reuse allows:
A) Antennas reuse only
B) Same frequency reused in distant cells to boost capacity
C) No reuse
D) Single channel per cell
**Answer: B**
22. Co-channel cells use:
A) Distinct frequencies
B) Same frequencies adequately spaced
C) Single frequency in cluster
D) Identical codes
**Answer: B**
23. The reuse distance formula D = R·√(3N) where N is cluster size: correct?
A) Yes
B) No
**Answer: A**
24. Fixed channel assignment means:
A) Channels flexibly allocated
B) Permanent static assignment
C) Borrowing from others
D) Shared code channels
**Answer: B**
25. Dynamic channel assignment involves:
A) Static allocation
B) Borrowing and assigning per call
C) No reuse
D) Fixed cluster size
**Answer: B**
26. Handoff occurs when mobile:
A) Moves within same cell
B) Moves into another cell during call
C) Idle state
D) Calls end
**Answer: B**
27. Guard channel strategy reserves channels for:
A) New calls
B) Handoff calls
C) Interference damping
D) Data only
**Answer: B**
28. Queuing handoff reduces:
A) Blocking new calls
B) Dropped handoff calls
C) Channel reuse
D) Transmission power
**Answer: B**
29. Soft handoff is:
A) Break before make
B) Make before break (connection overlaps)
C) Hard
D) Disruptive
**Answer: B**
30. MAHO stands for:
A) Mobile-assisted handoff
B) Macro antenna hopping
C) Manual assisted handoff
D) Mixed access handover
**Answer: A**
31. Dwell time is:
A) Time within cell before handoff trigger
B) Call duration
C) Paging delay
D) Frequency switch time
**Answer: A**
32. In cellular concept, a cluster is:
A) Frequency group
B) Set of cells using full frequency set once
C) Subscriber group
D) Antenna set
**Answer: B**
33. Main cellular aim is:
A) Larger cells
B) Frequency reuse
C) Satellite link
D) Single transmitter
**Answer: B**
34. Co-channel interference reduction factor q = D/R: for N=7, D/R ≈:
A) 3.46
B) 4.6
C) 7.6
D) 6
**Answer: B**
35. Hard handoff releases old connection before new:
A) True
B) False
**Answer: A**
36. Inter–MSC handoff means:
A) Same MSC
B) Between MSCs/different area
C) Intra-cell only
D) Within BSC
**Answer: B**
37. Power-difference handoff relies on:
A) Signal strength threshold
B) Only mobile speed
C) Static threshold
D) Neighbor assistance
**Answer: A**
38. Primary handoff goal:
A) Reduce channels
B) Minimize dropped calls
C) Maximize interference
D) Increase power
**Answer: B**
39. Channel assignment strategies include:
A) Only fixed
B) Only dynamic
C) Fixed and dynamic
D) None
**Answer: C**
40. A neighbor list is used for:
A) Sector planning
B) Handoff candidate selection
C) Frequency reuse
D) Power control
**Answer: B**
---
## 🟢 Unit III – System Capacity & Improvement Techniques (20 MCQs)
41. Co-channel interference arises from:
A) Adjacent channel only
B) Cells using same frequency
C) Thermal noise
D) No reuse
**Answer: B** ([Wikipedia][4], [mcq.electronics-club.com][8])
42. Adjacent channel interference is from:
A) Same channel reuse
B) Neighboring frequency overlap
C) Reflection only
D) No interference
**Answer: B**
43. Capacity improves by:
A) Bigger cells
B) Cell splitting
C) Removing sectors
D) Slower handoff
**Answer: B**
44. Cell sectoring divides:
A) Frequency evenly
B) A cell into directional sectors reducing interference
C) Channels temporally
D) Only spectrum
**Answer: B**
45. Repeaters are used for:
A) Reducing co‑channel interference
B) Range extension in weak coverage
C) Cell splitting
D) Frequency planning
**Answer: B**
46. Microcell zone concept uses:
A) Whole cell as a zone
B) Smaller zones within cell for trunking
C) Macro only
D) TDD only
**Answer: B**
47. Sectoring reduces:
A) Internal capacity
B) Interference and improves C/I
C) Frequency reuse
D) Power control
**Answer: B**
48. Cell splitting increases:
A) Cell radius
B) Number of cells in area
C) Carrier frequency
D) Interference
**Answer: B**
49. Microcells are used where:
A) Rural low density
B) Urban hotspots to boost capacity
C) Satellite coverage
D) EM interference zones
**Answer: B**
50. Splitting vs sectoring: splitting reduces cell size, sectoring reduces:
A) Time
B) Angle of coverage
C) Frequency bandwidth
D) Power
**Answer: B**
51. Capacity ∝:
A) Cluster size
B) Number of clusters replicated
C) Cell radius only
D) Channel width only
**Answer: B**
52. Interference can be mitigated by:
A) Increasing cell size
B) Frequency planning and sectoring
C) No reuse
D) Static assignment only
**Answer: B**
53. Cell splitting may lead to:
A) Lower capacity
B) Increased frequency reuse and capacity
C) Higher interference
D) Fewer channels
**Answer: B**
54. Using repeaters avoids:
A) Installing new base stations
B) Capacity increase
C) Sectoring
D) Frequency reuse
**Answer: A**
55. Microcell zone concept improves:
A) Spectral efficiency through better trunking
B) Only coverage
C) Only cell splitting
D) Satellite link
**Answer: A**
56. Sectoring commonly uses:
A) Omni antennas
B) 3 or 6 directional sectors
C) No antenna
D) Isotropic patterns
**Answer: B**
57. Co-channel interference reduction achieved by:
A) Increasing power
B) Frequency planning and sectoring
C) Removing reuse
D) None
**Answer: B**
58. Range extension via repeater is useful in:
A) Inner city core only
B) Shadow or fringe areas
C) Core network
D) Satellite base
**Answer: B**
59. Capacity improvement uses cell splitting, sectoring, and:
A) Larger cells
B) Microcell zoning
C) Longer channels
D) Reflectors only
**Answer: B**
60. Adjacent channel interference is minimized by:
A) No filtering
B) Filtering and guard bands
C) More power
D) Larger frequency reuse
**Answer: B**
---
## 🟢 Unit IV – Multipath Mitigation Techniques (20 MCQs)
61. Equalization combats:
A) Co-channel interference
B) ISI from multipath
C) Shadow fading
D) Larger cells
**Answer: B**
62. Adaptive equalizer adjusts:
A) Channel codes
B) Filter coefficients over time
C) Frequency reuse
D) Sector angle
**Answer: B**
63. Zero-forcing equalization aims to:
A) Neutralize intersymbol interference completely
B) Adjust power only
C) Sector cells
D) Increase noise
**Answer: A**
64. LMS equalizer uses:
A) Maximum likelihood
B) Gradient descent to minimize error
C) Static tap settings
D) High complexity only
**Answer: B**
65. Diversity combats fading by:
A) Single antenna
B) Multiple uncorrelated channels combined
C) Cell splitting
D) Frequency reuse
**Answer: B**
66. Micro diversity uses:
A) Separate sites
B) Closely spaced antennas
C) Time slots only
D) One antenna
**Answer: B**
67. Macro diversity uses:
A) Same cell antennas
B) Spatially separated base stations
C) Equalizer taps
D) Single antenna
**Answer: B**
68. Transmitter diversity means:
A) Multiple antennas at transmitter
B) Only at receiver
C) Larger cells only
D) Sectorization
**Answer: A**
69. Receiver diversity combines signals from:
A) One antenna
B) Multiple receive antennas
C) Multiple frequencies
D) Multiple base stations
**Answer: B**
70. Equalizer tap count depends on:
A) Doppler only
B) Delay spread length
C) Antenna height
D) Cell radius
**Answer: B**
71. LMS algorithm advantage:
A) No training sequence
B) Low complexity, adaptive
C) Zero noise
D) Infinite taps only
**Answer: B**
72. Zero forcing drawback:
A) No ISI removal
B) Noise amplification
C) Slow convergence
D) Sectoring only
**Answer: B**
73. Diversity gain improves:
A) Spectral efficiency
B) Link reliability
C) Handoff frequency
D) None
**Answer: B**
74. Equalizer is placed:
A) At transmitter only
B) At receiver to correct ISI
C) Inbetween cells
D) None
**Answer: B**
75. Combining techniques include:
A) Maximal ratio combining
B) Zero forcing only
C) Sectoring
D) Splitting
**Answer: A**
76. Diversity types include:
A) Frequency, time, space
B) Color, shape
C) Sectoring only
D) Splitting only
**Answer: A**
77. Adaptive equalizer needs:
A) Constant channel
B) Training/pilot sequence
C) More cells
D) Sectorization
**Answer: B**
78. Macro diversity especially helps in:
A) Indoor fading only
B) Base-station diversity for coverage
C) Equalization only
D) Channel reuse
**Answer: B**
79. Transmit diversity coding includes:
A) Spatial multiplexing only
B) Space–time coding
C) Sectorization
D) Reuse
**Answer: B**
80. LMS stands for:
A) Least Mean Squares
B) Linear Mean System
C) Layered Modulation Scheme
D) Low-power Multiplexing
**Answer: A**
---
## 🟢 Unit V – Multiple Antenna Techniques (20 MCQs)
81. MIMO stands for:
A) Multiple-input multiple-output
B) Mono input mono output
C) Master inter machine output
D) Multiple interface mod output
**Answer: A**
82. Spatial multiplexing uses:
A) Time division only
B) Multiple streams in parallel via multiple antennas
C) Larger cells
D) Frequency reuse only
**Answer: B**
83. Precoding requires:
A) No knowledge of channel
B) Channel state information (CSI) at transmitter
C) Larger cell size
D) Frequency reuse
**Answer: B**
84. Beamforming focuses energy:
A) Uniformly
B) In desired spatial direction
C) In code domain
D) In frequency domain
**Answer: B**
85. MIMO capacity grows with:
A) Transmission power only
B) Number of antennas and rich multipath
C) Sectoring
D) Larger cells
**Answer: B**
86. Without CSI, diversity coding uses:
A) Beamforming
B) Space-time coding
C) No diversity
D) Splitting only
**Answer: B**
87. Multi-user MIMO allows:
A) Single user only
B) Serving multiple users simultaneously spatially
C) Only beamforming
D) No CSI
**Answer: B**
88. Capacity in non-fading channel is:
A) Same as fading
B) Lower
C) Higher since no variability
D) Zero
**Answer: C**
89. Beamforming improves:
A) Interference suppression and SNR
B) Calls dropping rate
C) Cell radius only
D) Frequency reuse pattern
**Answer: A**
90. Pre‑coding transforms data before transmission using:
A) Random coding
B) CSI to improve performance
C) Sectoring only
D) Reuse only
**Answer: B**
91. Channel State Information helps determine:
A) Cell size
B) Optimal antenna weights
C) Handoff thresholds
D) Frequency reuse distance
**Answer: B**
92. Rich multipath is beneficial for MIMO because:
A) It degrades signal
B) Provides distinct spatial signatures
C) Causes scattering only
D) Limits capacity
**Answer: B**
93. Spatial multiplexing is limited by:
A) Number of antennas on smaller side (tx or rx)
B) Cell radius
C) Sectoring angle
D) Base station power
**Answer: A**
94. MIMO‑OFDM uses:
A) Only OFDM
B) Spatial multiplexing + OFDM for high spectral efficiency
C) Sectoring only
D) Single stream only
**Answer: B**
95. Spatial multiplexing without CSI at transmitter:
A) Requires precoding
B) Works with stream separation at receiver
C) Impossible
D) Degrades to SISO
**Answer: B**
96. Diversity coding is used when:
A) CSI unknown at transmitter
B) CSI known fully
C) Only one antenna
D) Macro cells only
**Answer: A**
97. Capacity in fading vs non-fading: fading can reduce average but MIMO helps restore via:
A) Sectoring only
B) Spatial multiplexing and diversity
C) Splitting only
D) Repeaters
**Answer: B**
98. Precoding helps:
A) Enhance beamforming and spatial multiplex gains
B) Interference only
C) Cell splitting only
D) Sectoring
**Answer: A**
99. Beamforming may reduce:
A) Multipath
B) Inter-cell interference
C) Frequency reuse
D) Handoff frequency
**Answer: B**
100. MIMO capacity theoretically grows without bound as antennas grow under ideal conditions:
A) True
B) False
**Answer: A** ---
Unit I MOBILE RADIO PROPAGATION
1.1: PROPAGATION MECHANISMS - Introduction to radio wave propagation (scattering, reflection, diffraction), Large scale path loss, small scale fading 1.2: PROPAGATION MODELS - Free space propagation model-Two ray model
Unit II CELLULAR CONCEPTS AND HANDOFF STRATEGIES
2.1: CELLULAR CONCEPTS- Introduction –frquency reuse, channel assignment strategies 2.2: HANDOFF STRATEGIES- Prioritizing Handoffs-Practical Handoff Considerations
Unit III SYSTEM CAPACITY AND CAPACITY IMPROVEMENT TECHNIQUES
3.1: INTERFERENCE AND SYSTEM CAPACITY- Co-channel interference - Adjacent Channel Interference-Interference- System Capacity 3.2: IMPROVING COVERAGE AND CAPACITY- Cell splitting and Cell sectoring - Repeaters for Range Extension – Micro cell Zone Concept
Unit IV MULTIPATH MITIGATION TECHNIQUES
4.1:EQUALIZATION - Equalization – Adaptive equalization-Zero forcing and LMS algorithms 4.2:DIVERSITY - Diversity – Micro and Macro diversity – transmitter diversity, receiver diversity
Unit V MULTIPLE ANTENNA TECHNIQUES
5.1: MIMO SYSTEMS - MIMO systems – spatial multiplexing-System model-Pre-coding – Beam forming 5.2: MIMO CAPACITY - Channel state information-capacity in fading and non-fading channels
