20 MCQ questions on Mobile Communication|Engineering Assistant Electronics

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20 MCQ questions on Mobile Communication: This quiz contains 20 multiple choice questions on Mobile Communication, covering key concepts, standards, and architectures relevant to the Electronics Engineering Assistant exam syllabus. This will help you focus on high-priority areas like cellular concepts, GSM, CDMA, and the evolution to 4G/5G.

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Q1. What is the main purpose of frequency reuse in a cellular mobile communication system?

A. To reduce the power consumption of mobile devices.

B. To increase the system capacity by using the same frequencies in different cells.

C. To ensure perfect synchronization between the base stations.

D. To eliminate the need for handovers between different cell sites.

  • Answer: B.
  • Explanation: Frequency reuse allows the limited radio spectrum to be used simultaneously in non-adjacent cells, dramatically increasing the total number of users the system can support (system capacity).

Q2. Which component in a GSM (2G) network is responsible for handling call setup, handover between cells, and routing calls to the appropriate destination?

A. Base Transceiver Station (BTS)

B. Mobile Switching Center (MSC)

C. Home Location Register (HLR)

D. Serving GPRS Support Node (SGSN)

  • Answer: B.
  • Explanation: The Mobile Switching Center (MSC) is the central switching office in the core network, acting as a gateway and coordinating all circuit-switched calls and mobility management.

Q3. Which multiple access technique is predominantly used by the GSM (2G) standard, dividing the channel into time slots?

A. Code Division Multiple Access (CDMA)

B. Frequency Division Multiple Access (FDMA)

C. Time Division Multiple Access (TDMA)

D. Orthogonal Frequency-Division Multiple Access (OFDMA)

  • Answer: C.
  • Explanation: GSM employs a combination of FDMA (dividing the spectrum into channels) and TDMA (dividing each channel into time slots for different users).

Q4. What is the primary multiple access technology introduced in 3G (UMTS) that allows multiple users to share the same frequency simultaneously using unique codes?

A. Narrowband TDMA

B. Wideband Code Division Multiple Access (W-CDMA)

C. Frequency Hopping Spread Spectrum (FHSS)

D. Orthogonal Frequency-Division Multiplexing (OFDM)

  • Answer: B.
  • Explanation: W-CDMA (Wideband CDMA) is the primary air interface technology for UMTS (3G), using unique spreading codes to differentiate users.

Q5. Which technology, often referred to as 2.5G, introduced packet-switched data and ‘always-on’ internet access capability to the GSM network?

A. General Packet Radio Service (GPRS)

B. High-Speed Downlink Packet Access (HSDPA)

C. Enhanced Data rates for GSM Evolution (EDGE)

D. Universal Mobile Telecommunications System (UMTS)

  • Answer: A.
  • Explanation: GPRS marked the transition from circuit-switched data to packet-switched data in GSM, enabling faster, ‘always-on’ mobile internet access.

Q6. What is the primary downlink multiple access technique utilized in 4G (LTE) to achieve high data rates and spectral efficiency?

A. Time Division Duplexing (TDD)

B. Code Division Multiple Access (CDMA)

C. Orthogonal Frequency-Division Multiple Access (OFDMA)

D. Single Carrier Frequency Division Multiple Access (SC-FDMA)

  • Answer: C.
  • Explanation: OFDMA is the downlink access method for 4G (LTE) and 5G due to its efficiency and robustness against multipath fading. SC-FDMA is used for the uplink.

Q7. What is a soft handover in mobile communications?

A. A handover that is initiated by the Mobile Switching Center (MSC).

B. The mobile station is simultaneously connected to more than one base station during the transition.

C. A handover that requires the mobile station to briefly drop the connection.

D. A handover between two different types of cellular systems (e.g., 3G to 4G).

  • Answer: B.
  • Explanation: A soft handover is a “make-before-break” transition, common in CDMA systems, where the mobile device maintains a connection with the old cell until the link with the new cell is fully established.

Q8. The phenomenon where a radio signal reaches the receiver via two or more paths due to reflection and scattering, causing time delay and interference, is called:

A. Ducting

B. Diffraction

C. Fading

D. Multipath Propagation

  • Answer: D.
  • Explanation: Multipath propagation occurs when signal copies arrive at the receiver at different times, causing delay spread and subsequent fading effects.

Q9. Which of the following is one of the three main use-case families defined for 5G technology, specifically designed to support massive numbers of low-power devices, such as those in the Internet of Things (IoT)?

A. URLLC (Ultra-Reliable Low-Latency Communication)

B. eMBB (Enhanced Mobile Broadband)

C. VoLTE (Voice over LTE)

D. mMTC (Massive Machine Type Communication)

  • Answer: D.
  • Explanation: mMTC targets applications with huge connection densities (billions of devices) that require long battery life and low data rates, such as IoT sensors.

Q10. In cellular system design, why are hexagonal cell shapes used for analysis and planning?

A. Hexagons provide the longest-range coverage for a given base station power.

B. Hexagons allow for easy tiling of the plane with no overlap or gaps, simplifying frequency reuse calculations.

C. Hexagons perfectly match the radiation pattern of a directional antenna.

D. Hexagons minimize the need for signal equalization at the receiver.

  • Answer: B.
  • Explanation: The hexagonal model is a convenient geometric abstraction that allows for tessellation (tiling the plane) without gaps, simplifying the calculation of co-channel interference and frequency reuse patterns.

Q11. Which type of fading is typically observed when there is no dominant line-of-sight path between the transmitter and receiver, and the signal is a sum of many reflected and scattered components?

A. Rician fading

B. Log-Normal fading

C. Rayleigh fading

D. Atmospheric fading

  • Answer: C.
  • Explanation: Rayleigh fading is the statistical model for signal strength variation in dense non-line-of-sight environments, common in urban areas.

Q12. What is the name of the simplified, all-IP core network architecture introduced with 4G (LTE)?

A. GPRS Core Network (GCN)

B. Evolved Packet Core (EPC)

C. Universal Mobile Telecommunications System (UMTS)

D. Radio Access Network (RAN)

  • Answer: B.
  • Explanation: The Evolved Packet Core (EPC) is the flat, all-IP core network for LTE, designed to handle both voice (via VoLTE) and data traffic efficiently.

Q13. In a 2G/3G mobile network, which database contains a subscriber’s permanent service profile, registered services, and home location information?

A. Mobile Switching Center (MSC)

B. Visitor Location Register (VLR)

C. Authentication Center (AuC)

D. Home Location Register (HLR)

  • Answer: D.
  • Explanation: The HLR is the central, permanent database storing the detailed subscriber profile and the address of the VLR where the user is currently located.

Q14. The term mmWave in 5G communication primarily refers to:

A. Low-frequency bands (sub-1 GHz) offering excellent range and penetration.

B. Mid-band frequencies (e.g., 2 GHz to 6 GHz) providing a balance of coverage and capacity.

C. High-frequency bands (e.g., 24 GHz to 100 GHz) offering massive bandwidth but short range.

D. The use of extremely small cell sizes (femtocells).

  • Answer: C.
  • Explanation: Millimeter Wave (mmWave) is the term for the high-frequency spectrum bands used in 5G, which provide vast capacity (bandwidth) but suffer from high path loss and low penetration.

Q15. What is the main benefit of Massive MIMO in 4G (LTE-Advanced) and 5G systems?

A. Reduced battery consumption for mobile devices.

B. Simplified core network architecture.

C. Significantly increased spectral efficiency and system throughput through spatial multiplexing.

D. Elimination of multipath fading effects.

  • Answer: C.
  • Explanation: Massive MIMO uses a large array of antennas to focus energy and serve multiple users simultaneously on the same frequency (spatial multiplexing), greatly boosting capacity and data rates.

Q16. The technique that uses two separate frequency bands for uplink (mobile to base station) and downlink (base station to mobile) communication simultaneously is known as:

A. Time Division Duplexing (TDD)

B. Frequency Division Duplexing (FDD)

C. Carrier Aggregation (CA)

D. Full Duplex (FD)

  • Answer: B.
  • Explanation: FDD uses separate frequency bands (a pair of channels) to allow simultaneous, continuous transmission and reception.

Q17. According to Shannon’s Theorem, the maximum data rate (channel capacity) of a communication channel is fundamentally limited by which two factors?

A. Transmission Power and Antenna Gain

B. Bandwidth and Signal-to-Noise Ratio (SNR)

C. Modulation Scheme and Error Correction Coding

D. Latency and Jitter

  • Answer: B.
  • Explanation: Shannon’s capacity formula is C = B \log_2(1 + SNR), showing that maximum capacity (C) is limited by the available Bandwidth (B) and the Signal-to-Noise Ratio (SNR).

Q18. Which digital modulation technique is capable of transmitting the highest number of bits per symbol in modern cellular systems like 4G and 5G to maximize spectral efficiency?

A. BPSK (Binary Phase Shift Keying)

B. 16-QAM (Quadrature Amplitude Modulation)

C. 256-QAM (Quadrature Amplitude Modulation)

D. OFDM (Orthogonal Frequency-Division Multiplexing)

  • Answer: C.
  • Explanation: 256-QAM transmits 8 bits (\log_2(256)) per symbol, offering the highest spectral efficiency among the options, though it requires a very clean, high-SNR channel.

Q19. Small cells (e.g., femtocells, picocells) are primarily deployed in cellular networks to:

A. Extend the network’s reach to isolated rural areas.

B. Increase the overall network coverage area by boosting power.

C. Improve coverage and capacity in densely populated or indoor areas by offloading traffic.

D. Replace the need for fiber-optic backhaul in the network.

  • Answer: C.
  • Explanation: Small cells are low-power nodes used to increase capacity and improve coverage in small, high-traffic areas where macro-cells are overloaded or cannot penetrate effectively.

Q20. What key technological difference primarily distinguishes 3G (UMTS) from 2G (GSM)?

A. The introduction of frequency reuse principles for capacity gain.

B. The shift from analog voice transmission to digital voice transmission.

C. Introduction of high-speed packet data and true Code Division Multiple Access (CDMA) on the air interface.

D. The transition to an all-IP network core (EPC).

  • Answer: C.
  • Explanation: 3G fundamentally shifted the focus to high-speed packet data and adopted W-CDMA as the primary radio access technology, providing a massive boost in capacity and data rates over 2G.

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