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Question 1. Which generation of wireless communication introduced digital cellular technology with digital voice and data services? A) 1G B) 2G C) 3G D) 4G Answer: B Explanation: 2G marked the transition from analog to digital cellular systems, introducing digital voice and data services such as GSM and CDMA. Question 2. Which of the following systems is primarily designed for low-power, long-range communication in IoT applications? A) WLAN B) WPAN C) NB-IoT D) Satellite Answer: C Explanation: Narrowband Internet of Things (NB-IoT) is designed for low-power, wide-area network coverage suitable for IoT devices with low data rates. Question 3. Which is an advantage of wireless communication over wired systems? A) Higher capacity B) Greater mobility and flexibility C) Less interference D) Easier to secure Answer: B Explanation: Wireless systems provide mobility and flexibility, allowing users to move freely without physical connections. Question 4. Which key performance metric measures the amount of data transmitted per unit bandwidth in a given time?
A) Capacity B) Coverage C) Spectral efficiency D) Power efficiency Answer: C Explanation: Spectral efficiency indicates how efficiently the spectrum is utilized, measured in bits/sec/Hz. Question 5. Reflection, diffraction, scattering, and absorption are examples of which propagation mechanism? A) Small-scale fading B) Large-scale fading C) Propagation mechanisms D) Interference effects Answer: C Explanation: These are fundamental propagation mechanisms affecting wireless signals as they travel through the environment. Question 6. Which path loss model is most appropriate for free space conditions? A) Log-distance model B) Okumura model C) Free space propagation model D) COST 231-Hata model Answer: C Explanation: The free space propagation model describes ideal line-of-sight conditions with no obstacles, suitable for free-space environments. Question 7. Which phenomenon causes multipath signals to arrive with different delays, leading to delay spread? A) Reflection
Answer: A Explanation: Shadowing, caused by obstacles blocking the path, is typically modeled as a log-normal distribution. Question 11. Thermal noise in wireless communication systems is primarily caused by: A) Inter-user interference B) Electronic components at finite temperature C) Multipath propagation D) External electromagnetic interference Answer: B Explanation: Thermal noise results from the random motion of electrons within electronic components, modeled as Additive White Gaussian Noise (AWGN). Question 12. ASK, FSK, PSK, and QAM are examples of which class of techniques? A) Error correction codes B) Digital modulation techniques C) Multiple access schemes D) Coding schemes for encryption Answer: B Explanation: These are fundamental digital modulation schemes used to encode information onto carrier signals. Question 13. Which digital modulation scheme typically offers the highest spectral efficiency? A) BPSK B) QPSK C) 16-QAM D) FSK Answer: C Explanation: 16-QAM offers higher spectral efficiency than BPSK and QPSK due to packing more bits per symbol.
Question 14. In Rayleigh fading channels, the Bit Error Rate (BER) performance generally: A) Is better than in Rician channels B) Is unaffected by fading C) Is worse than in AWGN channels at the same SNR D) Is independent of modulation scheme Answer: C Explanation: Rayleigh fading causes severe signal fluctuations, leading to higher BER compared to AWGN at the same SNR. Question 15. Which equalization technique aims to mitigate inter-symbol interference in frequency- selective channels using a linear filter? A) Decision Feedback Equalizer (DFE) B) Zero-Forcing (ZF) equalizer C) Maximum Likelihood (ML) detector D) Rake receiver Answer: B Explanation: The ZF equalizer applies a linear filter to invert channel effects, aiming to eliminate ISI, but may amplify noise. Question 16. Which diversity technique combines signals from multiple antennas with weights proportional to their SNR to maximize received SNR? A) Selection combining B) Maximal Ratio Combining (MRC) C) Equal gain combining D) Space diversity with switch-and-stay Answer: B Explanation: MRC weights each antenna's signal proportionally to its SNR to maximize combined SNR, improving reliability.
B) Call holding time distribution C) Traffic load in voice channels with queuing D) Handoff success rate Answer: A Explanation: Erlang B calculates the probability of call blocking in systems where blocked calls are cleared and no queuing occurs. Question 21. Which multiple access technique divides the bandwidth into orthogonal frequency subcarriers to mitigate ISI? A) FDMA B) TDMA C) CDMA D) OFDMA Answer: D Explanation: OFDMA partitions the spectrum into orthogonal subcarriers, combating ISI in multipath environments. Question 22. In FDMA systems, narrowband FDMA is characterized by: A) Wide channels with high data rates B) Narrow channels with low data rates C) Using code spreading for multiple access D) Time-based sharing of the channel Answer: B Explanation: Narrowband FDMA uses narrow frequency channels, typically for low data rate applications. Question 23. Which multiple access scheme assigns unique spreading codes to users, allowing simultaneous transmission over the same frequency band? A) FDMA B) TDMA
C) CDMA
D) OFDMA
Answer: C Explanation: CDMA employs spreading codes (e.g., Walsh codes) to enable multiple users to share the same spectrum simultaneously. Question 24. A significant challenge in CDMA systems is the near-far problem, which can be mitigated by: A) Power control B) Frequency hopping C) Time synchronization D) Antenna diversity Answer: A Explanation: Power control ensures that signals from different users arrive with similar power levels, reducing near-far effects. Question 25. OFDM's cyclic prefix is used primarily to: A) Increase data rate B) Mitigate inter-symbol interference from multipath delay spread C) Enhance security D) Reduce power consumption Answer: B Explanation: The cyclic prefix prevents ISI caused by multipath delay spread, maintaining orthogonality among subcarriers. Question 26. Which wireless technology is most associated with LTE architecture? A) OFDM and MIMO B) CDMA and TDMA C) FHSS and DSSS D) Zigbee protocol
Question 30. Zigbee is optimized for: A) High data rate multimedia streaming B) Low-power, low-data rate applications in IoT C) Satellite communication D) Cellular voice calls Answer: B Explanation: Zigbee is designed for low-power, low-data rate applications suitable for sensor and control networks. Question 31. GEO satellites are characterized by: A) Low altitude and low latency B) Medium altitude with moderate latency C) Geostationary orbit, fixed relative position, high latency D) Low latency but non-stationary position Answer: C Explanation: GEO satellites orbit at approximately 35,786 km, appearing stationary relative to Earth but with high latency. Question 32. Which component of a satellite communication system transmits the uplink signal from the ground station? A) Transponder B) Antenna C) Transmitter (on satellite) D) Receiver (on satellite) Answer: C Explanation: The uplink signal is transmitted from the ground station to the satellite's transponder or transceiver. Question 33. In MIMO systems, spatial multiplexing primarily aims to:
A) Increase diversity gain B) Improve security C) Increase channel capacity by transmitting different data streams simultaneously D) Reduce interference Answer: C Explanation: Spatial multiplexing transmits multiple independent data streams over multiple antennas to increase capacity. Question 34. Massive MIMO in 5G is distinguished by: A) Use of a few large antennas B) Deployment of hundreds of antennas at base stations C) Single antenna operation D) Use of only time division multiplexing Answer: B Explanation: Massive MIMO involves deploying large antenna arrays (hundreds of elements) to significantly boost capacity and reliability. Question 35. Cognitive Radio enables dynamic spectrum access by: A) Fixed frequency licensing B) Spectrum sensing and sharing in real-time C) Increasing transmit power D) Using only licensed bands Answer: B Explanation: Cognitive radio senses spectrum occupancy and dynamically shares or vacates spectrum to optimize usage. Question 36. Spectrum sensing in cognitive radio involves: A) Adjusting transmit power B) Detecting unused spectrum segments for opportunistic use C) Encrypting transmitted data
Explanation: Energy harvesting captures ambient energy (solar, RF, vibrations) to power or supplement wireless devices. Question 40. LoRa is a LPWAN technology optimized for: A) High data rate streaming B) Low-power, long-range communication for IoT C) Short-range Bluetooth applications D) Satellite uplinks Answer: B Explanation: LoRa provides low-power, long-range connectivity ideal for IoT applications with low data rates. Question 41. Which of the following is a primary vulnerability in wireless networks? A) Wired eavesdropping B) Signal jamming and eavesdropping over air interface C) Physical cable cuts D) Static IP assignment issues Answer: B Explanation: Wireless networks are vulnerable to eavesdropping and jamming because signals are transmitted over the air. Question 42. Which standard uses the GSM architecture and supports international roaming? A) LTE B) CDMA C) GSM D) Wi-Fi 802. Answer: C Explanation: GSM, the Global System for Mobile Communications, supports international roaming and uses its own architecture.
Question 43. In LTE architecture, the eNodeB functions as: A) The core network element handling all switching B) The base station responsible for radio resource management C) The subscriber identity module D) The backhaul link between users and the network Answer: B Explanation: The eNodeB is the LTE base station responsible for radio communication and resource management. Question 44. 5G's mMTC (massive Machine Type Communications) targets: A) High data rate multimedia streaming B) Large-scale IoT connectivity with low power and low data rates C) Enhanced mobile broadband D) Satellite communication only Answer: B Explanation: mMTC supports massive connectivity of IoT devices with low power and low data requirements. Question 45. Which WLAN standard introduces OFDMA for better spectral efficiency and latency reduction? A) 802.11a B) 802.11g C) 802.11ax (Wi-Fi 6) D) 802.11b Answer: C Explanation: 802.11ax (Wi-Fi 6) introduces OFDMA to improve efficiency and reduce latency in dense environments. Question 46. Which multiple access method is most suitable for supporting real-time voice and video in cellular systems?
B) TDMA
C) CDMA
D) OFDMA
Answer: D Explanation: OFDMA divides the spectrum into orthogonal subcarriers, allowing multiple users to transmit simultaneously. Question 50. Which characteristic distinguishes Wi-Fi 6 (802.11ax) from previous standards? A) Exclusive use of DSSS modulation B) Use of OFDMA and MU-MIMO for improved efficiency C) Dependence only on CSMA/CA D) Elimination of security features Answer: B Explanation: Wi-Fi 6 introduces OFDMA and multi-user MIMO to enhance spectral efficiency and support more devices. Question 51. Which type of satellite orbit offers the lowest latency for communication? A) GEO B) MEO C) LEO D) HEO Answer: C Explanation: LEO satellites orbit at low altitudes (~2000 km), resulting in lower latency compared to GEO and MEO. Question 52. In MIMO systems, the array gain refers to: A) The increase in data rate due to multiple antennas B) The gain achieved by beamforming and combining techniques to improve SNR C) The diversity gain from multiple paths D) The reduction in interference from other users
Answer: B Explanation: Array gain results from coherent combining of signals, enhancing the effective SNR. Question 53. Spectrum sensing in cognitive radio is primarily used to: A) Detect primary user activity to avoid interference B) Allocate fixed spectrum channels C) Encrypt data transmissions D) Optimize antenna radiation patterns Answer: A Explanation: Spectrum sensing detects primary user activity to enable secondary users to access spectrum without causing interference. Question 54. Which advantage is associated with software-defined radio (SDR)? A) Fixed hardware configuration B) Flexibility to change protocols and standards via software updates C) Limited compatibility with new standards D) Higher power consumption compared to traditional radios Answer: B Explanation: SDR's programmability allows it to adapt to multiple standards and protocols through software modifications. Question 55. In cooperative relay systems, the decode-and-forward protocol involves: A) Amplifying the received signal and forwarding it without decoding B) Decoding the received message, re-encoding, and transmitting it forward C) Sending the message directly without relaying D) Using multiple relays simultaneously without decoding Answer: B Explanation: Decode-and-forward relays decode the message before re-encoding and transmitting, improving reliability.
A) Wired communication standards B) Spectrum allocation and radiocommunication regulations globally C) Cellular handset manufacturing D) Internet protocols only Answer: B Explanation: ITU coordinates international spectrum management and radiocommunication standards. Question 60. Terahertz (THz) communication is anticipated to provide: A) Lower data rates than current microwave systems B) Extremely high data rates with short-range applications C) Satellite navigation services only D) Standard Wi-Fi coverage Answer: B Explanation: THz communication offers ultra-high data rates suitable for short-range, high-capacity links. Question 61. Visible Light Communication (VLC) primarily uses: A) Radio frequency spectrum B) Infrared spectrum C) Visible light spectrum, typically from LED sources D) Microwave spectrum Answer: C Explanation: VLC uses visible light, often from LED lighting, for wireless data transmission. Question 62. Reconfigurable Intelligent Surfaces (RIS) are used in wireless communications to: A) Act as passive reflectors to enhance signal propagation B) Replace base stations entirely C) Generate power for devices D) Increase interference intentionally Answer: A
Explanation: RIS are engineered surfaces that reflect and direct signals to improve coverage and capacity passively. Question 63. Which of the following is a primary challenge in Terahertz communications? A) Excessively high power efficiency B) Severe path loss and atmospheric absorption C) Universal compatibility with existing systems D) Lack of available spectrum Answer: B Explanation: Terahertz signals experience high path loss and atmospheric absorption, limiting their range. Question 64. Which multiple access scheme is most suitable for supporting massive connectivity in 5G? A) TDMA B) FDMA C) OFDMA D) CDMA Answer: C Explanation: OFDMA supports massive connectivity by allocating subcarriers to many users efficiently. Question 65. Which standard is the basis for 5G New Radio (NR)? A) LTE B) NR (New Radio) with flexible numerology and massive MIMO C) GSM D) Wi-Fi 6 Answer: B Explanation: 5G NR is designed with flexible frame structures, numerology, and massive MIMO to support diverse use cases. Question 66. Which is a key feature of 6G research directions?
