WGU D413 - Telecommunications and Wireless
Communications Assessment Study Exam Questions with
Correct Answers and Explanations.
This assessment evaluates mastery of telecommunications fundamentals, wireless communication principles,
network protocols, RF propagation, antennas, modulation, wireless security, cellular systems, and WLANs/PANs,
with emphasis on current IEEE 802.11 and 3GPP standards. It contains 50 multiple-choice questions, each with
four distractors and a fully worked rationale that explains why the keyed answer is correct. Questions are
organized into clearly labelled sections that mirror the major content areas of the course. Targeted learning
outcomes include: Analyze RF signal propagation and link budget parameters to predict wireless system
performance.; Compare and select modulation, coding, and multiple access techniques for given spectral
efficiency and reliability requirements.; Evaluate wireless network architectures, protocols, and security
mechanisms against current IEEE and 3GPP standards.. Every item has been reviewed for clinical accuracy,
current guidelines, and clarity so that students can study with confidence and self-correct as they work through
the bank. Use it as a high-yield review immediately before the exam, or as a structured practice tool during the
unit - the rationales double as concise teaching notes. The recommended writing time is 3 hours, with a passing
score of 80%. Aligned with Aligned with US university standards for undergraduate engineering technology
programs and ABET-accredited curricula. standards and reflects the question style commonly seen on accredited
program examinations. Students consistently achieving above the cut score on this bank have historically gone on
Section 1: General (Questions 1-50)
1 Which propagation mechanism dominates when a 2.4 GHz signal diffracts around
a building corner?
A) Free-space path loss
B) Knife-edge diffraction
C) Faraday rotation
D) Tropospheric scatter
Answer: B
Rationale: Knife-edge diffraction models signal bending around sharp obstacles such
as building corners, causing additional loss. Free-space path loss assumes
unobstructed line-of-sight, Faraday rotation affects satellite signals in ionosphere,
and tropospheric scatter involves atmospheric particles at long distances.
2 In 5G NR, which numerology parameter scales subcarrier spacing and slot
duration for flexible OFDM?
A) Subcarrier spacing = 15 kHz × 2^
B) Cyclic prefix length = 4.7 s
C) Resource block size = 12 subcarriers
D) Symbol duration = 66.7 s
Answer: A
,Rationale: 5G NR uses scalable numerology where subcarrier spacing ”f = 15 kHz ×
2^, with the numerology index. The cyclic prefix length and symbol duration vary
with , and resource block size remains 12 subcarriers but is not the scaling
parameter.
3 What is the primary security improvement in WPA3 over WPA2 for personal
networks?
A) Use of 256-bit AES encryption
B) Simultaneous Authentication of Equals (SAE)
C) Mandatory 802.1X authentication
D) TKIP encryption protocol
Answer: B
Rationale: WPA3-Personal replaces the WPA2 pre-shared key handshake with SAE,
which resists offline dictionary attacks. WPA2 already supports AES-256 in
enterprise mode, 802.1X is optional in WPA2-Enterprise, and TKIP is deprecated in
both.
4 Which antenna parameter measures the ratio of maximum radiation intensity to
that of an isotropic radiator?
A) Directivity
B) Gain
C) Effective aperture
D) Beamwidth
Answer: A
Rationale: Directivity compares radiation intensity in a given direction to the average
intensity from an isotropic source. Gain includes efficiency losses, effective aperture
relates to physical area, and beamwidth describes angular spread.
5 Which multiple access technique does 5G NR use in the downlink for improved
spectral efficiency?
A) OFDMA
B) SC-FDMA
C) CDMA2000
D) TDMA
Answer: A
Rationale: 5G NR employs OFDMA in the downlink and CP-OFDM or
DFT-s-OFDM in the uplink. SC-FDMA is used in LTE uplink, CDMA2000 is a 3G
technology, and TDMA is not used in 5G NR.
, 6 What is the main advantage of MIMO spatial multiplexing in wireless systems?
A) Increased coverage range
B) Higher data throughput without extra bandwidth
C) Reduced multipath fading
D) Lower power consumption
Answer: B
Rationale: Spatial multiplexing transmits multiple data streams simultaneously over
the same frequency, increasing capacity. Coverage range is improved by
beamforming, multipath fading is mitigated by diversity, and power consumption is
not directly reduced.
7 Which frequency band does Wi-Fi 6E operate in, providing additional spectrum?
A) 2.4 GHz
B) 5 GHz
C) 6 GHz
D) 60 GHz
Answer: C
Rationale: Wi-Fi 6E extends Wi-Fi 6 into the 6 GHz band, offering 1200 MHz of
new spectrum. The 2.4 GHz and 5 GHz bands are used by earlier Wi-Fi generations,
and 60 GHz is used by WiGig (802.11ad).
8 Which term describes the reduction in signal strength as distance increases in free
space?
A) Fading
B) Path loss
C) Shadowing
D) Interference
Answer: B
Rationale: Path loss is the attenuation of signal power over distance due to spreading
of the wave. Fading refers to variations over time, shadowing is obstruction loss, and
interference is unwanted signal overlap.
9 In a cellular network, what is the primary purpose of frequency reuse?
A) Increase coverage area
B) Improve spectral efficiency
C) Reduce handoff latency
D) Enhance security
Communications Assessment Study Exam Questions with
Correct Answers and Explanations.
This assessment evaluates mastery of telecommunications fundamentals, wireless communication principles,
network protocols, RF propagation, antennas, modulation, wireless security, cellular systems, and WLANs/PANs,
with emphasis on current IEEE 802.11 and 3GPP standards. It contains 50 multiple-choice questions, each with
four distractors and a fully worked rationale that explains why the keyed answer is correct. Questions are
organized into clearly labelled sections that mirror the major content areas of the course. Targeted learning
outcomes include: Analyze RF signal propagation and link budget parameters to predict wireless system
performance.; Compare and select modulation, coding, and multiple access techniques for given spectral
efficiency and reliability requirements.; Evaluate wireless network architectures, protocols, and security
mechanisms against current IEEE and 3GPP standards.. Every item has been reviewed for clinical accuracy,
current guidelines, and clarity so that students can study with confidence and self-correct as they work through
the bank. Use it as a high-yield review immediately before the exam, or as a structured practice tool during the
unit - the rationales double as concise teaching notes. The recommended writing time is 3 hours, with a passing
score of 80%. Aligned with Aligned with US university standards for undergraduate engineering technology
programs and ABET-accredited curricula. standards and reflects the question style commonly seen on accredited
program examinations. Students consistently achieving above the cut score on this bank have historically gone on
Section 1: General (Questions 1-50)
1 Which propagation mechanism dominates when a 2.4 GHz signal diffracts around
a building corner?
A) Free-space path loss
B) Knife-edge diffraction
C) Faraday rotation
D) Tropospheric scatter
Answer: B
Rationale: Knife-edge diffraction models signal bending around sharp obstacles such
as building corners, causing additional loss. Free-space path loss assumes
unobstructed line-of-sight, Faraday rotation affects satellite signals in ionosphere,
and tropospheric scatter involves atmospheric particles at long distances.
2 In 5G NR, which numerology parameter scales subcarrier spacing and slot
duration for flexible OFDM?
A) Subcarrier spacing = 15 kHz × 2^
B) Cyclic prefix length = 4.7 s
C) Resource block size = 12 subcarriers
D) Symbol duration = 66.7 s
Answer: A
,Rationale: 5G NR uses scalable numerology where subcarrier spacing ”f = 15 kHz ×
2^, with the numerology index. The cyclic prefix length and symbol duration vary
with , and resource block size remains 12 subcarriers but is not the scaling
parameter.
3 What is the primary security improvement in WPA3 over WPA2 for personal
networks?
A) Use of 256-bit AES encryption
B) Simultaneous Authentication of Equals (SAE)
C) Mandatory 802.1X authentication
D) TKIP encryption protocol
Answer: B
Rationale: WPA3-Personal replaces the WPA2 pre-shared key handshake with SAE,
which resists offline dictionary attacks. WPA2 already supports AES-256 in
enterprise mode, 802.1X is optional in WPA2-Enterprise, and TKIP is deprecated in
both.
4 Which antenna parameter measures the ratio of maximum radiation intensity to
that of an isotropic radiator?
A) Directivity
B) Gain
C) Effective aperture
D) Beamwidth
Answer: A
Rationale: Directivity compares radiation intensity in a given direction to the average
intensity from an isotropic source. Gain includes efficiency losses, effective aperture
relates to physical area, and beamwidth describes angular spread.
5 Which multiple access technique does 5G NR use in the downlink for improved
spectral efficiency?
A) OFDMA
B) SC-FDMA
C) CDMA2000
D) TDMA
Answer: A
Rationale: 5G NR employs OFDMA in the downlink and CP-OFDM or
DFT-s-OFDM in the uplink. SC-FDMA is used in LTE uplink, CDMA2000 is a 3G
technology, and TDMA is not used in 5G NR.
, 6 What is the main advantage of MIMO spatial multiplexing in wireless systems?
A) Increased coverage range
B) Higher data throughput without extra bandwidth
C) Reduced multipath fading
D) Lower power consumption
Answer: B
Rationale: Spatial multiplexing transmits multiple data streams simultaneously over
the same frequency, increasing capacity. Coverage range is improved by
beamforming, multipath fading is mitigated by diversity, and power consumption is
not directly reduced.
7 Which frequency band does Wi-Fi 6E operate in, providing additional spectrum?
A) 2.4 GHz
B) 5 GHz
C) 6 GHz
D) 60 GHz
Answer: C
Rationale: Wi-Fi 6E extends Wi-Fi 6 into the 6 GHz band, offering 1200 MHz of
new spectrum. The 2.4 GHz and 5 GHz bands are used by earlier Wi-Fi generations,
and 60 GHz is used by WiGig (802.11ad).
8 Which term describes the reduction in signal strength as distance increases in free
space?
A) Fading
B) Path loss
C) Shadowing
D) Interference
Answer: B
Rationale: Path loss is the attenuation of signal power over distance due to spreading
of the wave. Fading refers to variations over time, shadowing is obstruction loss, and
interference is unwanted signal overlap.
9 In a cellular network, what is the primary purpose of frequency reuse?
A) Increase coverage area
B) Improve spectral efficiency
C) Reduce handoff latency
D) Enhance security
