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WorksheetsTEST 1 MCQ - ITA0306 - MOBILE COMPUTING
Total questions: 100
Worksheet time: 2hrs 40mins
Name
Class
Date
1.
1. Two adjacent cells reuse the same frequency causing interference. If desired signal = 10 mW and interference = 2 mW, SIR (dB) at receiver ≈?
a)
3.01 dB
b)
5 dB
c)
3.98 dB
d)
7 dB
2.
2. A hexagonal cell has side length 1 km. Approximate area (km²) is?
a)
1.732
b)
4.5
c)
2.598
d)
3.464
3.
3. If a mobile moves from cell A to B, handoff latency <200 ms. Signaling = 80 ms, route switch = 90 ms. Remaining budget for authentication?
a)
20 ms
b)
40 ms
c)
50 ms
d)
30 ms
4.
4. Given co-channel interference ratio = 18 dB. Interferer = -90 dBm. Minimum desired signal?
a)
-100 dBm
b)
-72 dBm
c)
-90 dBm
d)
-108 dBm
5.
5. Cell radius halves, area reduces 4×. If original capacity per cell = C, new capacity per unit area ≈?
a)
C/4
b)
4C
c)
16C
d)
C
6.
6. Base station serves 600 users, 100 channels, each user offers 0.02 Erlangs. Blocking probability ≈?
a)
0.12
b)
0.6
c)
0.02
d)
0.0004
7.
7. Frequency reuse distance D = R√(3N). R=1 km, N=7. Approximate D?
a)
2.64 km
b)
3 km
c)
4.58 km
d)
1.73 km
8.
8. Propagation loss exponent = 4. Doubling distance changes power by factor?
a)
4
b)
16
c)
8
d)
2
9.
9. Mobile transmits 0 dBm; path loss = 80 dB. Received power?
a)
-80 dBm
b)
-8 dBm
c)
8 dBm
d)
80 dBm
10.
10. Two carriers: 900 MHz and 1800 MHz. Which has longer wavelength & better penetration?
a)
900 MHz
b)
1800 MHz
c)
Both same
d)
Neither
11.
11. Load balancing handoff triggers when cell load > threshold. Purpose?
a)
Reduce load in congested cell
b)
Reduce power
c)
Increase interference
d)
Decrease capacity
12.
12. Base Station Subsystem fails. Which subsystem handles switching to another BS?
a)
HLR
b)
PLMN
c)
Network Switching Subsystem
d)
Mobile Station
13.
13. TDMA frame: 8 slots, frame time = 4.615 ms. Slot duration ≈?
a)
0.577 ms
b)
1.154 ms
c)
0.36 ms
d)
0.77 ms
14.
14. Paging to 3 cells, cost per cell = 2 ms. Total paging delay?
a)
9 ms
b)
3 ms
c)
2 ms
d)
6 ms
15.
15. PLMN elements include:
a)
HLR, VLR, MSC
b)
GPS, GSM, LTE
c)
DNS, DHCP, FTP
d)
HTTP, SMTP, POP
16.
16. Base station cluster N=4, total channels=300. Channels per cell?
a)
33
b)
100
c)
50
d)
300
17.
17. Propagation: PL(dB)=PL0+10n log10(d/d0). PL0=40 dB @ d0=1 m, n=3, d=100 m. PL≈?
a)
100 dB
b)
80 dB
c)
70 dB
d)
1000 dB
18.
18. Cell load increases, call drop probability target = 0.02, observed=0.05. Immediate measure?
a)
Reduce carrier count
b)
Increase cell radius
c)
Increase handoff priority
d)
Decrease TX power
19.
19. Channel: 20 kHz, modulation needs 2 kHz/user. Max simultaneous users ≈?
a)
5
b)
10
c)
20
d)
40
20.
20. Handoff fails if signal below threshold > 2 s. What happens?
a)
Call pauses
b)
Handoff fails -> possible drop
c)
Handoff completes later
d)
Nothing
21.
21. Increasing frequency reuse distance mainly reduces:
a)
Interference
b)
Power
c)
Channels
d)
Latency
22.
22. Cell radius = 1 km, capacity = 200 Erlangs. Erlang density =?
a)
50 Erlang/km²
b)
100 Erlang/km²
c)
200 Erlang/km²
d)
400 Erlang/km²
23.
23. MS measures RSCP=-65 dBm, Ec/No=-6 dB. Status?
a)
Excellent quality
b)
Interference-free
c)
No connection
d)
Signal OK, low quality
24.
24. Mobile moves 60 km/h, cell radius 1 km. Handoff frequency per hour ≈?
a)
~36
b)
~60
c)
~6
d)
~1
25.
25. Core network primary function?
a)
Switching & routing
b)
Powering BS
c)
Manufacturing handsets
d)
Managing antennas
26.
26. Interference margin =10 dB, thermal noise=-100 dBm. Desired signal ≥?
a)
-100 dBm
b)
-90 dBm
c)
-80 dBm
d)
-110 dBm
27.
27. Overflow in cellular occurs when:
a)
All channels busy & call blocked
b)
Only SMS sent
c)
MS battery low
d)
TX power too high
28.
28. Channel coding reduces raw BER by 10× but halves data rate. Net throughput effect?
a)
Might decrease/increase
b)
Always decreases
c)
Always increases
d)
No change
29.
29. Doubling users with same channels increases blocking probability?
a)
Decreases
b)
Increases
c)
Same
d)
Zero
30.
30. TDMA/GSM: How many bits per time slot for full-rate voice 13 kbps over 0.577 ms slot?
a)
7.5 bits
b)
7.4 bits
c)
7.5 bits rounded
d)
8 bits
31.
31. GSM: How many time slots per carrier?
a)
4
b)
2
c)
8
d)
16
32.
32. TDMA frame repeats every 4.615 ms, voice sample every 20 ms. Frames between samples ≈?
a)
~5
b)
~2
c)
~4
d)
~10
33.
33. FDMA: Channel width 200 kHz, total 25 MHz. Number of carriers?
a)
50
b)
125
c)
25
d)
200
34.
34. CDMA capacity: How does capacity change with spread factor?
a)
Increases with lower spread factor
b)
Depends on modulation
c)
Unrelated
d)
Increases with higher spread factor
35.
35. OFDMA reduces ISI by:
a)
Increasing power
b)
Increasing packet size
c)
Reducing modulation
d)
Subcarrier orthogonality & cyclic prefix
36.
36. GSM authentication: RAND=32-bit. Number of possible challenges?
a)
2^32
b)
32
c)
2^64
d)
2^16
37.
37. GPRS improves:
a)
Spectrum efficiency for burst data
b)
Voice quality
c)
Antenna gain
d)
Handover rate
38.
38. HSCSD aggregates 4 slots, 14.4 kbps each. Total rate ≈?
a)
14.4 kbps
b)
28.8 kbps
c)
72 kbps
d)
57.6 kbps
39.
39. UMTS soft handover possible due to:
a)
FDMA only
b)
Satellite link
c)
Common frequency used by neighboring cells
d)
Different frequency per cell
40.
40. 1G drawbacks:
a)
Poor security, low capacity, high interference
b)
High data rates
c)
Strong encryption
d)
IP-based routing
41.
41. SDMA with beamforming improves:
a)
More handoffs
b)
Lower battery life
c)
Simpler hardware
d)
Increased spatial reuse
42.
42. OFDMA subcarrier blocks: Scheduling benefit?
a)
Larger guard bands
b)
Single-user only
c)
No benefit
d)
Flexibility for multiuser diversity
43.
43. GSM BCCH carries:
a)
Billing info
b)
System info like neighbor lists
c)
Voice traffic
d)
User data
44.
44. Hopping sequence uses 8 channels, uniform error. Diversity gain ≈?
a)
4
b)
√8
c)
8
d)
2
45.
45. Timing advance unit ≈?
a)
550 m
b)
50 m
c)
1 km
d)
100 m
46.
46. Ciphering disabled attack:
a)
Faster handover
b)
Better throughput
c)
Longer battery
d)
Eavesdropping
47.
47. LTE evolution from UMTS:
a)
Removal of SIM cards
b)
All-IP flat architecture
c)
Return to analog
d)
Use of FDMA only
48.
48. Radio interface BER target 10^-3, measured 10^-2. Fastest improvement?
a)
Increase coding or retransmission
b)
Increase cell radius
c)
Reduce modulation to analog
d)
Remove error checking
49.
49. 2G→3G spectral efficiency improves because of:
a)
More SMS
b)
Bigger phones
c)
CDMA & better modulation
d)
More antennas only
50.
50. DECT main usage:
a)
WiFi replacement
b)
Satellite comms
c)
Short-range cordless telephony
d)
Cellular backbone
51.
51. GSM: 200 kHz carriers, 124 carriers. Total spectrum ≈?
a)
12.4 MHz
b)
24.8 MHz
c)
2.48 MHz
d)
200 MHz
52.
52. OFDMA combats frequency-selective fading via:
a)
Subcarrier orthogonality & cyclic prefix
b)
Increasing transmit power
c)
Single-carrier only
d)
TDMA slots
53.
53. Handover decision: Combine RSS & QoS → best method?
a)
Weighted metric of RSS & load
b)
Random
c)
QoS alone
d)
RSS alone
54.
54. TDD duplexing advantage:
a)
Asymmetric allocation flexibility
b)
Better voice quality inherently
c)
No frame timing
d)
Requires paired spectrum only
55.
55. GSM SDCCH used for:
a)
Encryption key exchange only
b)
Signaling & control during call setup
c)
Billing only
d)
Carrying voice
56.
56. Channel coding reduces BER 10× but halves rate. Net throughput effect?
a)
Always decreases
b)
Might decrease/increase
c)
No change
d)
Always increases
57.
57. Make-before-break (soft) handover advantage?
a)
Needs no signaling
b)
Lower call drop risk
c)
Simpler resource usage
d)
No extra resources
58.
58. 5G NSA initial connection uses:
a)
Satellite link
b)
4G anchor then 5G NR for data
c)
3G fallback
d)
5G only
59.
59. Smaller cells → handover rate? Cell radius reduced 4×.
a)
1
b)
2
c)
4
d)
16
60.
60. GSM location update messages go to?
a)
FTP
b)
DNS
c)
HLR
d)
SQL
61.
61. Mobile Node moves at 30 m/s, triangle cell radius 500 m. Average handoff events per hour ≈?
a)
216
b)
60
c)
36
d)
72
62.
62. Mobile IP triangle routing problem: Home→FA→CN path = 300 ms, direct MN→CN = 120 ms. Extra latency =?
a)
180 ms
b)
420 ms
c)
150 ms
d)
300 ms
63.
63. MN sends 5 kb packet via FA to CN. Tunnel overhead = 40 bytes. Effective payload efficiency ≈?
a)
0.99
b)
0.92
c)
0.88
d)
0.95
64.
64. Ad hoc network 20 nodes, proactive routing table size = n(n-1) = ?
a)
380
b)
400
c)
420
d)
360
65.
65. MN moves across 4 subnets, each update latency = 50 ms. Total registration delay?
a)
100 ms
b)
150 ms
c)
200 ms
d)
250 ms
66.
66. Reactive routing discovers path 3 hops, each hop delay 10 ms, discovery latency = 20 ms. End-to-end latency?
a)
40 ms
b)
50 ms
c)
60 ms
d)
30 ms
67.
67. Triangle routing overhead = 15%. MN sends 10 MB. Extra data due to triangle routing?
a)
1.5 MB
b)
0.5 MB
c)
1 MB
d)
2 MB
68.
68. MN moves from subnet A→B→C, hop distances 2, 3, 4 km. Max RA lifetime 2 s. MN speed =?
a)
4 km/s
b)
3 km/s
c)
1 km/s
d)
2 km/s
69.
69. Proactive routing table update interval = 5 s. Node moves at 10 m/s. Max distance moved between updates?
a)
50 m
b)
100 m
c)
10 m
d)
25 m
70.
70. MN sends packet 1 kb, round-trip via HA = 150 ms, via direct = 90 ms. Delay saved by route optimization?
a)
60 ms
b)
50 ms
c)
30 ms
d)
45 ms
71.
71. Mobile IP registration fails after 3 attempts, each 50 ms, retry backoff 100 ms. Total wait time?
a)
300 ms
b)
350 ms
c)
400 ms
d)
450 ms
72.
72. Ad hoc network, 50 nodes, link failure probability = 0.1 per hop. 3-hop path, end-to-end success probability?
a)
0.9
b)
0.729
c)
0.81
d)
0.99
73.
73. MN moves at 60 km/h, ping interval 1 s, cell radius 500 m. Probability ping occurs during handoff ≈?
a)
0.08
b)
0.2
c)
0.15
d)
0.12
74.
74. Mobile IP triangular path: HA→FA→CN adds 40 ms extra per packet, 100 packets. Total extra delay?
a)
4 s
b)
0.4 s
c)
40 s
d)
400 ms
75.
75. MN moves fast, handoff latency 120 ms. Maximum tolerable packet size for VoIP 20 ms jitter?
a)
1500 B
b)
1200 B
c)
500 B
d)
1000 B
76.
76. MN has 2 interfaces, dual registration. HA→CN latency 200 ms per interface. Average latency?
a)
100 ms
b)
200 ms
c)
150 ms
d)
250 ms
77.
77. Ad hoc routing, 5 hops, each 10 ms, route discovery 50 ms. Packet end-to-end delay?
a)
100 ms
b)
80 ms
c)
150 ms
d)
200 ms
78.
78. MN handover occurs every 30 s, ping 1 s interval. Average packet loss per hour if loss = 2 packets/handoff?
a)
240
b)
360
c)
120
d)
180
79.
79. Triangle routing: Packet 1 kb, header 40 bytes. Overhead percentage?
a)
0.04
b)
0.03
c)
0.02
d)
0.05
80.
80. Mobile IP registration via FA = 2 hops, each 50 ms. Time to propagate HA update?
a)
100 ms
b)
50 ms
c)
200 ms
d)
150 ms
81.
81. Reactive routing discovery broadcasts = 10 packets/node, 20 nodes. Total control packets?
a)
200
b)
180
c)
220
d)
150
82.
82. MN moves from subnet A→B→C, each hop 1 km, handoff time 0.5 s, speed = 1.5 m/s. Time to cross C?
a)
666 s
b)
1000 s
c)
1200 s
d)
500 s
83.
83. Mobile IP: TTL=64, packets loop 2 times erroneously. Extra hops counted =?
a)
128
b)
2
c)
64
d)
32
84.
84. MN moves at 90 km/h, ping interval 1 s, cell radius 600 m. Expected handoffs/hour?
a)
90
b)
60
c)
150
d)
120
85.
85. Ad hoc network: 5 hops, each hop BER=10^-3, end-to-end BER ≈?
a)
0.005
b)
0.00499
c)
0.01
d)
0.003
86.
86. MN sends 10 MB via triangle route. Header 40 B per packet, 1000 B packet size. Overhead %?
a)
0.04
b)
0.004
c)
0.02
d)
0.002
87.
87. Mobile IP: MN moves every 5 s, registration = 50 ms. Fraction of time updating?
a)
0.01
b)
0.02
c)
0.05
d)
0.005
88.
88. MN speed = 36 km/h, cell radius 1 km, handoff latency = 120 ms. Fraction of time in handoff?
a)
0.01
b)
0.02
c)
0.03
d)
0.04
89.
89. Triangle routing adds 15% latency. Base RTT = 200 ms. Total RTT?
a)
215 ms
b)
230 ms
c)
220 ms
d)
250 ms
90.
90. Mobile IP fails when HA unreachable. MN continues traffic via FA?
a)
Yes, with routing
b)
No
c)
Only DNS works
d)
Only ARP works
91.
91. Android app memory limit = 256 MB, app allocates 180 MB heap, 30 MB bitmap. Remaining memory?
a)
50 MB
b)
36 MB
c)
46 MB
d)
40 MB
92.
92. iOS Core Data fetch 5000 objects, batch size=500. Number of fetches needed?
a)
5
b)
8
c)
10
d)
12
93.
93. Android Dalvik VM GC pause = 50 ms per 1 MB. App allocates 4 MB. Total pause?
a)
220 ms
b)
200 ms
c)
180 ms
d)
150 ms
94.
94. J2ME MIDP app, CLDC heap = 1 MB, 4 objects 200 KB each. Heap remaining?
a)
200 KB
b)
600 KB
c)
400 KB
d)
800 KB
95.
95. Symbian app: CPU usage 30%, screen refresh = 16 FPS. Max CPU left for background tasks?
a)
0.7
b)
0.5
c)
0.4
d)
0.6
96.
96. Windows Phone app: 1 s UI animation, frame interval = 16 ms. Frames per animation ≈?
a)
64
b)
62
c)
60
d)
50
97.
97. Palm OS app: Heap fragmentation = 25%, heap size=512 KB, allocatable memory?
a)
384 KB
b)
128 KB
c)
256 KB
d)
512 KB
98.
98. Android intents: App sends broadcast to 5 receivers, processing delay per receiver = 20 ms. Total delay?
a)
80 ms
b)
120 ms
c)
60 ms
d)
100 ms
99.
99. BlackBerry OS background process runs every 5 min. Battery usage per run=2%. Total 1 hour?
a)
0.3
b)
0.12
c)
0.2
d)
0.24
100.
100. Android Service handles 500 requests/min, each takes 200 ms. Max throughput?
a)
50 req/sec
b)
60 req/sec
c)
30 req/sec
d)
40 req/sec
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