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Odisha CHSE +2 Vocational Mobile Technology study materials
Odisha CHSE +2 Vocational Mobile Technology study resources

Odisha CHSE +2 Vocational Mobile Technology practice questions

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Question 1Mobile Phone Fundamentals and Hardware Architecture

In a mobile phone, which component is primarily responsible for converting the radio-frequency signal received by the antenna into a lower-frequency signal that the baseband circuit can process?

  1. The power management IC
  2. The display driver IC
  3. The audio codec
  4. The transceiver (RF section) Correct answer.

Explanation

The RF transceiver handles modulation and demodulation, down-converting incoming RF to baseband and up-converting baseband to RF for transmission. The power management IC regulates voltages, the display driver drives the panel, and the audio codec handles sound conversion, so none of them performs RF frequency translation.

Question 2Mobile Phone Fundamentals and Hardware Architecture

Which type of memory in a smartphone retains its stored data even when power is removed and typically holds the operating system and user files?

  1. SRAM cache
  2. LPDDR system RAM
  3. DRAM working memory
  4. NAND flash storage Correct answer.

Explanation

NAND flash is non-volatile, so it keeps the operating system, applications and user data when the phone is switched off. SRAM, DRAM and LPDDR are all volatile and lose their contents without power, serving only as working memory while the device runs.

Question 3Mobile Phone Fundamentals and Hardware Architecture

A technician replaces a smartphone battery and finds the phone will not charge. Which measurement would most directly confirm whether the charging port is delivering power to the board?

  1. Frequency of the camera clock signal
  2. Capacitance of the display backlight circuit
  3. Resistance of the loudspeaker coil
  4. Voltage across the battery connector pads while the charger is connected Correct answer.

Explanation

Measuring voltage at the battery connector with the charger attached shows whether power is reaching the board through the port and charging circuit. Speaker resistance, backlight capacitance and camera clock frequency are unrelated to the charging path and would not reveal a port fault.

Question 4Mobile Phone Fundamentals and Hardware Architecture

Which component of a mobile handset generates the clock signals that synchronise the processor, memory and peripheral buses?

  1. The vibration motor driver
  2. The SIM card interface
  3. The crystal oscillator and clock generator circuit Correct answer.
  4. The touchscreen controller

Explanation

A crystal oscillator produces a stable reference frequency that the clock generator divides and distributes to synchronise digital circuits. The SIM interface, touch controller and motor driver are peripherals that consume timing signals rather than create the system clock.

Question 5Mobile Phone Fundamentals and Hardware Architecture

In a block diagram of a smartphone, the baseband processor is best described as the part that:

  1. converts AC mains input into a regulated DC supply
  2. stores the phone's factory calibration data permanently
  3. amplifies the audio signal delivered to the earpiece speaker
  4. performs digital signal processing for communication protocols and controls the radio modem Correct answer.

Explanation

The baseband processor runs the modem protocol stack and performs digital signal processing for encoding, decoding and channel handling. Audio amplification, permanent calibration storage and AC-to-DC conversion belong to the audio amplifier, flash memory and charger circuitry respectively.

Question 6Mobile Phone Fundamentals and Hardware Architecture

A phone shows no display but vibrates and rings on incoming calls. Which conclusion is most reasonable for a hardware technician?

  1. The baseband processor has failed completely
  2. The SIM card is not seated correctly
  3. The main processor and radio sections are functioning, so the fault lies in the display path Correct answer.
  4. The battery has reached end of life

Explanation

Vibration and ringing prove that the processor, radio and audio subsystems are alive, which localises the fault to the display path such as the panel, flex cable or display connector. A dead baseband, flat battery or unseated SIM would not produce normal call alerting with an intact display path explanation.

Question 7Mobile Phone Fundamentals and Hardware Architecture

Which statement correctly distinguishes an SoC from a discrete-component design in mobile phones?

  1. An SoC cannot include a memory controller
  2. An SoC contains only the CPU, while all other functions remain separate chips
  3. An SoC integrates CPU, GPU, modem and other blocks on a single die, reducing size and power use Correct answer.
  4. A discrete design always consumes less power than an SoC

Explanation

A system-on-chip combines the application processor, graphics unit, modem, memory controller and other blocks on one die, which shrinks board area and interconnect power. Discrete designs spread these functions across separate packages, and an SoC commonly does include a memory controller.

Question 8Mobile Phone Fundamentals and Hardware Architecture

The IMEI of a mobile handset is stored in which area of the phone's hardware?

  1. The display panel's driver IC
  2. The removable SIM card only
  3. A protected region of the baseband or non-volatile memory associated with the modem Correct answer.
  4. The camera image sensor module

Explanation

The IMEI identifies the handset itself and is held in protected non-volatile storage tied to the baseband/modem section, not on the SIM. The SIM carries the subscriber identity (IMSI), while display drivers and camera modules hold no device identity data.

Question 9Mobile Phone Fundamentals and Hardware Architecture

Which hardware block is responsible for stepping down the lithium-ion battery voltage to the multiple regulated rails required by the processor and peripherals?

  1. The gyroscope sensor
  2. The power management IC with its buck and LDO regulators Correct answer.
  3. The RF front-end module
  4. The touchscreen digitiser

Explanation

The power management IC contains switching buck converters and linear regulators that produce the various stable supply voltages from the battery. The RF front-end, digitiser and gyroscope are functional blocks that consume power rather than regulate it.

Question 10Mobile Phone Fundamentals and Hardware Architecture

A phone's touchscreen responds to touches but the image on the panel is normal. Which pair of subsystems should the technician separate during diagnosis?

  1. The battery from the charging port
  2. The speaker from the microphone
  3. The digitiser/touch controller from the display panel and its driver Correct answer.
  4. The SIM reader from the memory card slot

Explanation

Touch sensing and image display are separate paths: the digitiser and touch controller handle input while the panel and display driver handle output. Since the image is normal, the fault is isolated to the touch path rather than the display path.

Question 11Mobile Phone Fundamentals and Hardware Architecture

Which antenna configuration is commonly used in modern smartphones to support multiple frequency bands and MIMO operation within a compact chassis?

  1. A ferrite rod antenna mounted externally
  2. A parabolic dish embedded in the back cover
  3. A single large whip antenna
  4. Multiple integrated antenna elements tuned for different bands Correct answer.

Explanation

Smartphones use several compact, band-tuned antenna elements placed around the chassis to support multi-band and MIMO operation. Whip, ferrite rod and parabolic antennas are bulky or directional designs unsuited to a slim handset.

Question 12Mobile Phone Fundamentals and Hardware Architecture

During boot, a phone repeatedly restarts before reaching the home screen. Which hardware fault is most consistent with this symptom?

  1. A worn volume-up keycap
  2. A dead earpiece speaker
  3. A scratched rear camera lens
  4. An unstable power rail causing voltage droop under load Correct answer.

Explanation

Repeated restarts during boot typically indicate that a supply rail cannot hold its voltage when the processor draws current, triggering a reset. A faulty speaker, scratched lens or worn keycap would not interrupt the boot sequence.

Question 13Mobile Phone Fundamentals and Hardware Architecture

Which type of display technology produces light from individual organic emitters and therefore needs no separate backlight?

  1. AMOLED Correct answer.
  2. TN LCD
  3. IPS LCD
  4. TFT LCD

Explanation

AMOLED panels use organic light-emitting diodes that generate their own light per pixel, so no backlight unit is required. IPS, TN and TFT are all liquid-crystal variants that depend on a separate backlight to illuminate the panel.

Question 14Mobile Phone Fundamentals and Hardware Architecture

A lithium-ion battery in a handset is marked 3.85 V nominal and 4000 mAh. What does the mAh rating express?

  1. The charge capacity, i.e. current delivered over time Correct answer.
  2. The maximum charging voltage
  3. The peak discharge current
  4. The internal resistance of the cell

Explanation

The milliampere-hour rating states charge capacity as the product of current and time, so 4000 mAh means 4 A for one hour in principle. Voltage, internal resistance and peak current are separate specifications not conveyed by the mAh figure.

Question 15Mobile Phone Fundamentals and Hardware Architecture

Which soldering consideration is most important when reworking a fine-pitch BGA power management IC on a smartphone board?

  1. Using the highest available iron temperature without flux
  2. Controlled reflow temperature profile and precise ball alignment Correct answer.
  3. Removing all surrounding shielding permanently
  4. Applying mechanical force to press the chip down

Explanation

BGA packages have hidden solder balls underneath, so a controlled reflow profile and accurate alignment are needed to form reliable joints without damaging the board. Excess iron temperature, mechanical force and removing shielding all risk board damage or solder defects.

Question 16Mobile Phone Fundamentals and Hardware Architecture

A phone reports a weak cellular signal although the antenna spring contacts look clean. Which measurement best verifies whether the antenna is actually connected to the RF front-end?

  1. Resistance of the earpiece coil
  2. Continuity between the antenna feed pad and the front-end module input Correct answer.
  3. Capacitance across the loudspeaker terminals
  4. Battery voltage at the connector

Explanation

Checking continuity from the antenna feed point to the front-end module input confirms whether the RF path is intact through the spring contact and matching network. Battery voltage, earpiece resistance and speaker capacitance belong to the power and audio paths and say nothing about antenna connectivity.

Question 17Mobile Phone Fundamentals and Hardware Architecture

Which statement about the application processor and the baseband processor in a typical smartphone is correct?

  1. Both processors are always the same physical die performing identical tasks
  2. The baseband processor runs the operating system while the application processor manages the radio
  3. The application processor handles cellular protocol processing, while the baseband runs the user interface
  4. The application processor runs the operating system and apps, while the baseband handles cellular protocol processing Correct answer.

Explanation

The application processor executes the operating system, user interface and applications, whereas the baseband processor runs the cellular modem protocol stack. They are distinct functional units even when integrated on one SoC die, and their roles are not interchangeable.

Question 18Mobile Phone Fundamentals and Hardware Architecture

Which sensor in a smartphone provides data used to automatically rotate the screen orientation?

  1. The ambient light sensor
  2. The fingerprint sensor
  3. The accelerometer Correct answer.
  4. The proximity sensor

Explanation

The accelerometer measures gravitational direction along its axes, allowing the system to detect orientation and rotate the display. The proximity sensor detects nearby objects, the light sensor measures illumination and the fingerprint sensor captures biometric data.

Question 19Mobile Phone Fundamentals and Hardware Architecture

A technician measures 0 V at the battery connector but 5 V at the charging port pins with the charger connected. What is the most likely interpretation?

  1. The antenna has been disconnected
  2. The display driver is drawing excessive current
  3. The battery is fully charged and needs no current
  4. The charging circuit between the port and battery is open or faulty Correct answer.

Explanation

Power arriving at the port but not reaching the battery connector indicates a break or failure in the charging path, such as a damaged charging IC or open trace. A full battery would still show its own terminal voltage, and display or antenna faults do not interrupt the charging path.

Question 20Mobile Phone Fundamentals and Hardware Architecture

Which bus is typically used inside a smartphone to connect high-speed components such as the application processor to LPDDR memory?

  1. The I2C serial bus
  2. The USB OTG bus
  3. The SIM interface
  4. A dedicated high-speed parallel memory interface Correct answer.

Explanation

LPDDR memory connects to the application processor through a dedicated wide, high-speed parallel interface designed for low power and high bandwidth. I2C is a slow control bus, USB OTG is an external peripheral link and the SIM interface serves the smart card.

Question 21Mobile Phone Fundamentals and Hardware Architecture

Which component converts the digital audio stream from the processor into an analogue signal for the earpiece speaker?

  1. The power management IC
  2. The RF transceiver
  3. The audio codec (DAC section) Correct answer.
  4. The display driver IC

Explanation

The audio codec contains a digital-to-analogue converter that turns digital audio samples into the analogue waveform fed to the amplifier and speaker. The power management, RF and display driver blocks serve entirely different functions.

Question 22Mobile Phone Fundamentals and Hardware Architecture

A phone's proximity sensor fails, so the screen stays on during calls and accidental touches occur. Which hardware area should be inspected first?

  1. The charging port contacts
  2. The main camera module
  3. The vibration motor
  4. The IR emitter and detector assembly near the earpiece and its flex connection Correct answer.

Explanation

Proximity sensing relies on an infrared emitter and detector, usually located near the earpiece, together with its flex connection to the board. Camera, motor and charging port faults would not cause the screen to remain active against the user's face.

Question 23Mobile Phone Fundamentals and Hardware Architecture

Which statement best explains why smartphones use switching buck converters rather than only linear regulators for their main supply rails?

  1. Buck converters waste less power as heat, extending battery life Correct answer.
  2. Buck converters remove the need for any battery
  3. Linear regulators cannot step voltage down at all
  4. Buck converters are always smaller than linear regulators

Explanation

Switching buck converters transfer energy efficiently and dissipate far less heat than linear regulators, which burn the voltage difference as heat. Linear regulators can step voltage down and are still used for low-current rails, and no regulator eliminates the need for a battery.

Question 24Mobile Phone Fundamentals and Hardware Architecture

Which of the following best describes the function of the SIM card interface circuit in a handset?

  1. It stores the phone's operating system image
  2. It amplifies the radio signal for transmission
  3. It converts touch input into digital coordinates
  4. It supplies the correct voltage and clock to the SIM and carries data between the SIM and the baseband Correct answer.

Explanation

The SIM interface provides the regulated supply, clock and data lines required by the smart card and connects it to the baseband for authentication. It does not store the operating system, amplify radio signals or process touch input.

Question 25Mobile Phone Fundamentals and Hardware Architecture

A technician finds that a phone charges normally but the battery percentage drops unusually fast during use. Which measurement set would most usefully distinguish a failing battery from excessive load current?

  1. Antenna continuity and RF signal strength
  2. Display refresh rate and touch sampling rate
  3. Speaker coil resistance and microphone sensitivity
  4. Battery voltage under load together with current drawn by the system Correct answer.

Explanation

Comparing terminal voltage under load with the actual current drawn shows whether the cell is sagging because of high internal resistance or whether the system is simply consuming too much. Audio, RF and display parameters do not reveal battery health or load current.

Question 26Mobile Phone Fundamentals and Hardware Architecture

In a smartphone hardware block diagram, which group of components is contained inside the application processor subsystem rather than being a separate chip on the main board?

  1. Charger IC, fuel gauge and USB protection switch
  2. Power amplifier, antenna switch and duplexer
  3. Earpiece driver, microphone bias circuit and headphone jack
  4. CPU cores, graphics unit, image signal processor and memory controller Correct answer.

Explanation

The application processor is a highly integrated chip that combines the general-purpose CPU cores with the graphics unit, image signal processor, memory controller and other accelerators on one die. The other listed blocks are power-path, radio-frequency front-end and audio analogue functions that remain separate components or sit in other subsystems.

Question 27Mobile Phone Fundamentals and Hardware Architecture

A handset's main camera produces sharp images but every photo appears washed out with a strong pink cast. Which hardware area should the technician investigate first?

  1. The vibration motor and its drive circuit
  2. The earpiece speaker mesh and its acoustic channel
  3. The infrared proximity sensor calibration data
  4. The camera connector and flex cable, checking for bent pins or a partially seated connector Correct answer.

Explanation

A colour cast with otherwise correct focus and exposure points to a disturbed image-data path, typically a camera flex connector that is loose, corroded or has bent pins so some data lanes are corrupted. The camera module itself, its connector and the flex cable are therefore the first items to reseat and inspect.

Question 28Mobile Phone Fundamentals and Hardware Architecture

A phone's display works, but the digitizer reports touch coordinates that are offset by roughly one centimetre from the point actually pressed. Which explanation is most consistent with this symptom?

  1. The main microphone has a blocked acoustic port
  2. The display backlight driver is supplying too little current
  3. The battery fuel gauge is reporting an incorrect state of charge
  4. The touch controller's calibration or firmware configuration does not match the panel fitted Correct answer.

Explanation

When touches register but at a shifted position, the sensing hardware is working while the mapping between raw sensor values and screen coordinates is wrong. This happens when the touch controller firmware or calibration profile does not match the particular panel and resolution installed, for example after a replacement screen.

Question 29Mobile Phone Fundamentals and Hardware Architecture

A technician must select a replacement battery for a handset whose original cell is marked 3.85 V nominal, 4300 mAh, with a 4.4 V charge limit. Which choice is correct?

  1. A 3.7 V nominal cell of 4300 mAh whose charge cut-off is 4.2 V
  2. A 4.4 V nominal cell of 4300 mAh whose charge cut-off is 4.2 V
  3. A 3.85 V nominal cell of 4300 mAh or more whose charge cut-off is 4.4 V Correct answer.
  4. A 3.85 V nominal cell of 2000 mAh whose charge cut-off is 4.4 V

Explanation

The replacement must match the nominal voltage and the charge cut-off voltage, because the charging circuit terminates at a fixed limit and over-charging a lower-limit cell damages it. Capacity may be equal or higher, so a 3.85 V cell with a 4.4 V limit and at least 4300 mAh is the safe match.

Question 30Mobile Phone Fundamentals and Hardware Architecture

A handset with a fully charged battery draws almost no current when off, but on power-up the current briefly rises and then falls to near zero with no boot. Which measurement sequence best isolates whether the fault lies in the power delivery path or in the processor subsystem?

  1. Replace the battery, then replace the display, then replace the camera module
  2. Check each regulator rail for its expected voltage at power-up, then probe the processor clock and reset lines Correct answer.
  3. Reinsert the SIM card and then reformat the user data partition
  4. Test the speaker and microphone, then test the vibration motor

Explanation

A brief current pulse followed by collapse suggests the supply starts but a rail fails or the processor never leaves reset. Verifying each regulator output establishes whether power delivery is intact, and probing clock and reset confirms whether the processor is being released to run. This separates a supply fault from a processor-side fault before any parts are replaced.

Question 31Mobile Communication Systems and Networks

In a cellular network, what is the main purpose of frequency reuse?

  1. To serve more subscribers within a limited radio spectrum by reusing channels in distant cells Correct answer.
  2. To increase the transmit power of every base station
  3. To convert analogue voice into digital packets
  4. To eliminate the need for handover between cells

Explanation

Frequency reuse assigns the same set of channels to cells that are far enough apart that co-channel interference stays acceptable. This lets an operator serve many more subscribers with a fixed spectrum allocation. It does not remove handover, raise power, or perform speech coding.

Question 32Mobile Communication Systems and Networks

A cluster of N cells uses the complete set of available channels once. Which expression gives the co-channel reuse ratio Q in terms of N?

  1. Q = √N
  2. Q = N/3
  3. Q = 3N
  4. Q = √(3N) Correct answer.

Explanation

For a hexagonal cell layout the co-channel reuse ratio is Q = D/R = √(3N), where D is the distance between co-channel cell centres and R is the cell radius. This follows from the geometry of hexagonal clusters, where N = i² + ij + j². The other expressions do not match that geometry.

Question 33Mobile Communication Systems and Networks

Which handover type is described as a mobile moving from one cell to another while both cells belong to the same MSC?

  1. Intra-MSC handover Correct answer.
  2. International roaming handover
  3. Inter-MSC handover
  4. Inter-system handover

Explanation

Handovers are classified by the network entities involved. When the old and new cells are controlled by the same Mobile Switching Centre, the procedure is an intra-MSC handover and is handled internally by that MSC. Inter-MSC handover involves signalling between two different MSCs.

Question 34Mobile Communication Systems and Networks

During a hard handover in a GSM network, what happens to the radio link with the old base station?

  1. It is released before or at the moment the new link is established Correct answer.
  2. It is converted into a broadcast control channel
  3. It is maintained in parallel with the new link for the whole call
  4. It is kept open until the subscriber ends the call

Explanation

GSM uses hard handover, meaning the mobile breaks the old connection and then makes the new one, so there is a brief interruption. The parallel-link arrangement describes soft handover used in CDMA systems. Keeping the old link for the whole call is not how handover works.

Question 35Mobile Communication Systems and Networks

Which multiple access scheme assigns each user a unique orthogonal spreading code and shares the entire bandwidth simultaneously?

  1. TDMA
  2. CDMA Correct answer.
  3. FDMA
  4. SDMA

Explanation

Code Division Multiple Access spreads every user's signal across the whole band using a distinct orthogonal code, so all users transmit at the same time. FDMA separates users by frequency and TDMA by time slots. SDMA separates users by spatial direction.

Question 36Mobile Communication Systems and Networks

In a GSM frame structure, how many traffic channels can a single TDMA carrier support when full-rate speech coding is used?

  1. 4
  2. 8 Correct answer.
  3. 2
  4. 16

Explanation

A GSM TDMA carrier is divided into frames of eight time slots, and with full-rate speech coding each slot carries one speech channel. Hence one carrier supports eight simultaneous full-rate calls. Half-rate coding would double that figure.

Question 37Mobile Communication Systems and Networks

What is the primary function of the Home Location Register in a GSM network?

  1. To perform speech transcoding between codecs
  2. To route calls between two MSCs
  3. To store the permanent subscriber profile and current location information Correct answer.
  4. To allocate radio channels inside a single cell

Explanation

The HLR is a central database holding each subscriber's permanent data, such as subscription details and services, together with the identity of the visitor location register currently serving them. Channel allocation is done by the base station controller, and routing is done by the MSC.

Question 38Mobile Communication Systems and Networks

A mobile station is powered on in a visited network. Which register first receives its location update so the home network can route incoming calls correctly?

  1. The Gateway MSC, which then informs the base transceiver station
  2. The Equipment Identity Register, which then informs the base station
  3. The Visitor Location Register, which then informs the Home Location Register Correct answer.
  4. The Authentication Centre, which then informs the base station controller

Explanation

When a subscriber registers in a new area, the serving VLR records the location and updates the HLR so that incoming calls can be forwarded to the correct MSC. The HLR then holds a pointer to that VLR. The EIR, AuC and GMSC do not perform this location registration step.

Question 39Mobile Communication Systems and Networks

Which frequency band is commonly used for the uplink in the GSM 900 system?

  1. 1805–1880 MHz
  2. 890–915 MHz Correct answer.
  3. 935–960 MHz
  4. 1710–1785 MHz

Explanation

In GSM 900 the mobile-to-base uplink occupies 890–915 MHz and the base-to-mobile downlink occupies 935–960 MHz, giving a duplex spacing of 45 MHz. The 1710–1785 and 1805–1880 MHz ranges belong to the DCS 1800 band.

Question 40Mobile Communication Systems and Networks

Why is a guard band inserted between adjacent frequency channels in an FDMA system?

  1. To reduce the physical height of the antenna
  2. To increase the total number of available channels
  3. To prevent spectral overlap and adjacent-channel interference Correct answer.
  4. To carry the synchronisation burst of each user

Explanation

Real filters have finite roll-off, so signals in neighbouring channels would overlap without a gap. A guard band absorbs this spectral spillage and keeps adjacent-channel interference low. It reduces rather than increases the number of usable channels.

Question 41Mobile Communication Systems and Networks

A mobile transmitter radiates 20 W. Expressed in dBm, this is closest to which value?

  1. 43 dBm Correct answer.
  2. 33 dBm
  3. 13 dBm
  4. 20 dBm

Explanation

First convert to milliwatts: 20 W = 20 000 mW. Then apply dBm = 10 log10(P/1 mW) = 10 log10(20 000) ≈ 43 dBm. The value 33 dBm corresponds to 2 W, and 13 dBm to about 20 mW.

Question 42Mobile Communication Systems and Networks

What does a path-loss exponent of about 4 in a mobile radio channel typically indicate?

  1. A free-space link with a clear line of sight
  2. A satellite link with almost no attenuation
  3. An urban environment with obstructions where signal falls off rapidly with distance Correct answer.
  4. A waveguide with negligible loss

Explanation

In free space the received power falls as the square of distance, giving an exponent of 2. A value near 4 indicates a cluttered urban environment where buildings and obstacles add shadowing, so the signal decays much faster with distance.

Question 43Mobile Communication Systems and Networks

Which propagation mechanism allows a mobile in a shadowed urban street to receive a signal around the corner of a building?

  1. Polarisation
  2. Reflection only
  3. Absorption
  4. Diffraction Correct answer.

Explanation

Diffraction is the bending of radio waves around the edges of obstacles such as building corners, which lets a signal reach shadowed areas. Absorption removes energy rather than redirecting it, and reflection alone does not explain reception around a corner in a shadow region.

Question 44Mobile Communication Systems and Networks

Fading in which the received signal amplitude varies rapidly over very short distances or time because of multipath is called what?

  1. Fast fading Correct answer.
  2. Flat fading
  3. Shadow fading
  4. Slow fading

Explanation

Fast fading arises from the interference of multipath components and changes over distances on the order of a wavelength or over milliseconds. Slow fading varies over much longer distances, flat fading refers to the bandwidth relationship, and shadow fading is caused by large obstacles.

Question 45Mobile Communication Systems and Networks

A receiver uses two antennas spaced several wavelengths apart to combine independently faded copies of the signal. Which technique is being used?

  1. Channel coding
  2. Frequency hopping
  3. Spatial diversity Correct answer.
  4. Power control

Explanation

Spatial diversity exploits the fact that antennas separated by several wavelengths experience largely uncorrelated fading, so combining their outputs reduces the probability of a deep fade. Frequency hopping, power control and channel coding improve reliability but are not diversity by antenna spacing.

Question 46Mobile Communication Systems and Networks

Which of the following best describes the role of the base station controller in a GSM network?

  1. It performs authentication using the subscriber identity module
  2. It provides the interface to the public switched telephone network
  3. It stores the subscriber's permanent subscription data
  4. It manages radio resources for several base transceiver stations and controls handover between them Correct answer.

Explanation

The BSC sits between the MSC and a group of BTSs and owns radio resource management, including channel allocation and handover decisions within its area. Subscriber data is held in the HLR, and the PSTN interface is provided by the MSC.

Question 47Mobile Communication Systems and Networks

What is the main advantage of a microcellular layout with smaller cells in a dense city?

  1. Complete removal of multipath fading
  2. Higher capacity and lower transmit power per cell Correct answer.
  3. Abolition of the need for frequency planning
  4. Elimination of handover entirely

Explanation

Smaller cells allow the same spectrum to be reused more often and shorten the radio path, so both capacity and battery life improve while interference falls. Handover becomes more frequent, not unnecessary, and multipath fading still occurs.

Question 48Mobile Communication Systems and Networks

A network uses a cluster size N = 7. What is the approximate co-channel reuse ratio Q?

  1. About 2.6
  2. About 21.0
  3. About 7.0
  4. About 4.6 Correct answer.

Explanation

Using Q = √(3N) with N = 7 gives Q = √21 ≈ 4.58. This means co-channel cells are about 4.6 cell radii apart. The values 2.6, 7.0 and 21.0 do not follow from the formula.

Question 49Mobile Communication Systems and Networks

In a CDMA system, why must strict power control be applied on the uplink?

  1. So that the spreading codes become non-orthogonal
  2. So that time slots do not overlap between users
  3. So that signals from all mobiles arrive at the base station with similar power and the near-far problem is avoided Correct answer.
  4. So that each mobile uses a different frequency channel

Explanation

In CDMA all users share the same band, so a mobile close to the base station would otherwise swamp weaker signals from distant mobiles. Equalising received power at the base station keeps the multiple-access interference manageable, which is the near-far problem.

Question 50Mobile Communication Systems and Networks

Which statement correctly describes the difference between soft handover and hard handover?

  1. Soft handover is used only between different countries, whereas hard handover is used within a cell
  2. Soft handover applies only to data calls, whereas hard handover applies only to voice calls
  3. Soft handover breaks the old link before making the new one, whereas hard handover keeps both
  4. Soft handover keeps the old link while the new one is set up, whereas hard handover breaks before making Correct answer.

Explanation

In soft handover the mobile is connected to two or more base stations simultaneously during the transition, so no interruption occurs. Hard handover releases the old channel before or at the moment the new channel is established, causing a short break.