Part A: General Questions (Conceptual Understanding)
1
Which IEEE 802.15 standard defines the Low-Rate Wireless Personal Area Network (LR-WPAN) that forms the basis for Zigbee technology?
A IEEE 802.15.1
B IEEE 802.15.4
C IEEE 802.15.3
D IEEE 802.15.6
2
What is the maximum theoretical data rate specified for IEEE 802.15.1 (Bluetooth Classic) in the original standard?
A 1 Mbps
B 2 Mbps
C 250 kbps
D 20 Mbps
3
Which frequency band is primarily used by IEEE 802.15.4 (Zigbee) for worldwide operation?
A 402-405 MHz (MICS band)
B 868 MHz (Europe only)
C 2.4 GHz ISM band
D 5-50 MHz (HBC band)
4
IEEE 802.15.6 (WBAN) defines three Physical Layer (PHY) variants. Which of the following is NOT one of them?
A Narrowband (NB) PHY
B Ultra-Wideband (UWB) PHY
C Human Body Communication (HBC) PHY
D Frequency Hopping Spread Spectrum (FHSS) PHY
Part B: Analytical Questions (Application & Analysis)
5
In a Zigbee mesh network, if a router node fails, what mechanism allows the network to maintain communication between end devices and the coordinator?
A Beacon frame retransmission
B Self-healing through route discovery
C Automatic coordinator reassignment
D Direct sequence spread spectrum
6
A communication engineer needs to design a wireless sensor network for industrial monitoring with the following requirements: low data rate (< 50 kbps), long battery life (> 2 years), and support for mesh topology. Which IEEE 802.15 standard variant should be selected?
A IEEE 802.15.1 (Bluetooth Classic)
B IEEE 802.15.3 (High-Rate WPAN)
C IEEE 802.15.4 (LR-WPAN) with Zigbee
D IEEE 802.15.6 (WBAN)
7
In IEEE 802.15.4, what happens when both the Beacon Order (BO) and Superframe Order (SO) are set to 15?
A The network operates in non-beacon mode using unslotted CSMA/CA
B The superframe duration becomes 15.36 ms
C The network switches to Guaranteed Time Slots (GTS) only
D The coordinator transmits beacons every 15 seconds
8
Which channel access mechanism in IEEE 802.15.6 (WBAN) is most appropriate for emergency medical event reporting requiring immediate transmission without contention?
A Random Access Phase (RAP) using CSMA/CA
B Contention Access Phase (CAP)
C CSMA/CA in non-beacon mode
D Exclusive Access Phase (EAP) with highest user priority
Part C: Quantitative Questions (Calculations & Numerical Analysis)
9
In IEEE 802.15.1 (Bluetooth), the frequency hopping spread spectrum uses 79 channels with a hop rate of 1600 hops/second. What is the dwell time (time spent on each channel) during normal operation?
A 625 μs
B 1 ms
C 625 μs (calculated as 1/1600 s)
D 1.25 ms
10
An IEEE 802.15.4 network operates in the 2.4 GHz band with a symbol rate of 62.5 ksymbols/s. If the Beacon Order (BO) is set to 3, what is the approximate beacon interval?
A 15.36 ms
B 122.88 ms
C 245.76 ms
D 491.52 ms
11
In IEEE 802.15.4 O-QPSK modulation at 2.4 GHz, the raw data rate is 250 kbps. If a packet contains a 7-byte payload, 11-byte MAC header, and 2-byte FCS (total 20 bytes = 160 bits), what is the minimum theoretical transmission time for this packet?
A 0.64 ms
B 1.28 ms
C 0.32 ms
D 2.56 ms
12
A WBAN using IEEE 802.15.6 UWB PHY operates with a power spectral density emission limit of -41.3 dBm/MHz. If the signal bandwidth is 500 MHz, what is the total maximum transmit power?
A -41.3 dBm
B -14.3 dBm
C -41.3 + 10log₁₀(500) ≈ -14.3 dBm
D -41.3 + 10log₁₀(500) ≈ -14.3 dBm (approximately 0.037 mW)