This set of Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) focuses on “802.11 Enhancements”.
1. Which of the following enhancement techniques is utilized by IEEE 802.11 to facilitate user experience in denser environments?
a) Median filtering
b) Decorrelation stretch
c) Morphological operators filtering
d) Fast Initial Link Set-up
View Answer
Explanation: IEEE enhancements including IEEE 802.11ai provides Fast Initial Link Set-up techniques to improve user experiences in denser environments and this standard additionally exhibits throughput in multi-gigabit ranges at 5 GHz and 60 GHz frequency bands.
2. Which of the following is not a functionality of IEEE 802.11ai?
a) Scalability
b) Minimizing time interval
c) Interoperability
d) Enhanced authentication
View Answer
Explanation: IEEE 802.11ai amendment accepts challenges where massive mobile users enter and leave an existing Extended Service Set (ESS). It additionally provides better scalability when multiple users enter ESS simultaneously, reduces time wasted while link is initiated and enhances authentication.
3. IEEE 802.11ai improves multiple user connectivity by promoting reliable connection utilizing protocol overhead optimization.
a) True
b) False
View Answer
Explanation: IEEE 802.11ai exponentially promotes user connectivity in denser environments including stadiums, malls and even airports. They also provide reliable and secured connection, enabling increased spectrum utilization by protocol overhead optimization method in denser circumstances.
4. Which of the following IEEE 802.11 enhancement technique is extensively utilized in Television White Spaces (TWS) applications?
a) IEEE 802.11aa
b) IEEE 802.11ad
c) IEEE 802.11af
d) IEEE 802.11ac
View Answer
Explanation: IEEE 802.11 amendment is revised for including standards which promote multi- gigabit throughput capability especially at operating ranges of 5 GHz and 60 GHz. IEEE 802.11aa is exploited for audio video streaming, IEEE 802.11ad is utilized for enhancing throughput at 60 GHz, IEEE 802.11af is used in TWS operation and IEEE 802.11ac is deployed in enhancing throughput in sub-6 GHz bands.
5. Which frequencies does the IEEE 802.11 enhancement standard provide enhanced physical layer functionalities?
a) 5 and 28 GHz
b) 2.4 and 5 GHz
c) 3.6 and 6 GHz
d) 5 and 7 GHz
View Answer
Explanation: IEEE 802.11 enhancement standard provides enhanced physical layer functionalities between 2.4 GHz and 5 GHz frequency range. Additionally it provides Wireless Local Area Network (WLAN) solution at 60 GHz and Television White Spaces (TWS) operating frequencies. Management frames flow control, audio- video streaming enhancements and TWS database control activities are promoted within MAC layer.
6. What is the physical data rate and operating frequency band of IEEE 802.11ac standard?
a) 7Gbps, 60 GHz
b) 5Gbps, 60 GHz
c) 3Gbps, 5 GHz
d) 7Gbps, 5 GHz
View Answer
Explanation: IEEE 802.11ac is a currently emerging enhanced throughput Wireless Local Area Network (WLAN) standard which attains data rates roughly within 7Gbps at 5 GHz resonating frequency. Media Access Control (MAC) performance can be extensively determined using various frame aggression techniques including, Aggregate MAC protocol data unit (A-MPDU), Aggregate MAC Service Data Unit (A-MSDU) and hybrid A-MSDU/A-MPDU aggregation.
7. Which of the following enhancement techniques of IEEE 802.11 standard offers maximum throughput?
a) IEEE 802.11ac
b) IEEE 802.11ai
c) IEEE 802.11b
d) IEEE 802.11g
View Answer
Explanation: When Media Access Control (MAC) performance techniques were experimentally deployed using Aggregate MAC protocol data unit (A-MPDU), Aggregate MAC Service Data Unit (A-MSDU) and hybrid A-MSDU/A-MPDU aggregation methods, results validate that the performance of IEEE 802.11ac is comparatively better in throughput functionality when compared with other enhancement standards including IEEE 802.11ai, IEEE 802.11b and IEEE 802.11g respectively.
8. IEEE 802.11n provides only Media Access Control (MAC) enhancements.
a) True
b) False
View Answer
Explanation: IEEE 802.11 enhancement standards feature higher throughputs with maximum of 100 Mb/s and is generally measured at MAC data service access points. However, IEEE 802.11n enables both MAC and physical layer enhancements. Frame aggression techniques implemented at physical-MAC level, single rate-multi rate and uplink- downlink measurements validates the standards performance at both physical and MAC layers.
9. Which one of the following IEEE 802.11 enhancement standards is used in beamforming and Quadrature Amplitude Modulation (QAM) at 60 GHz?
a) IEEE 802.11j
b) IEEE 802.11e
c) IEEE 802.11h
d) IEEE 802.11k
View Answer
Explanation: IEEE 802.11j is utilized in Media Access Control (MAC) enhancements in audio and video streaming applications and IEEE 802.11e is deployed for enhancing Quality of Service in network management. IEEE 802.11h is extensively used for selecting frequency dynamically at 3.6 GHz in USA and IEEE 802.11k is deployed in beamforming and QAM applications at 60 GHz resonating frequency.
10. Which of the following characteristics is false considering IEEE 802.11g standard?
a) Offers data rates upto 54 Mbit/s
b) 2.4 GHz resonating frequency
c) Excellent propagation characteristics at 5 GHz
d) Backward compatible with IEEE 802.11b
View Answer
Explanation: IEEE 802.11g amendment features enhanced variation of IEEE 802.11 standard which offers extensive data rate capability of 54 Mbit/s resonating at 2.4 GHz. Additionally, it is designed for supporting backward compatibility with IEEE 802.11b and its propagation characteristics at 2.4 GHz is more prominent when compared with features at 5 GHz.
11. Which of the following Wireless Local Area Network (WLAN) standards utilize 5GHz operating frequency?
a) IEEE 802.11a
b) IEEE 802.11
c) IEEE 802.11b
d) IEEE 802.11g
View Answer
Explanation: WLAN standards mainly deploy two operating frequencies namely 2.4 GHz and 5 GHz which is deployed in its enhancement standards. IEEE 802.11, IEEE 802.11b and IEEE 802.11g utilize 2.4 GHz offering data rates of 2Mbps, 11Mbps and 54Mbps respectively. IEEE 802.11a resonates at 5 GHz with maximum data rate of 54Mbps.
12. Shading is more severe at 5 GHz compared to 2.4 GHz in IEEE 802.11k standard.
a) True
b) False
View Answer
Explanation: IEEE 802.11a operates efficiently at 5 GHz and offers data bit rates upto 54 Mbps. Shading conditions are more prone to occur at 5 GHz when compared to 2.4 GHz frequency band. Speed at which data rates drop entirely depends upon propagation conditions, SNR (Signal to Noise Ratio) and interval between transmitter and receiver.
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