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Communications MCQ Set 1

1. First generation cellular and cordless telephone networks are based on _________
a) Analog technology
b) Digital technology
c) Active technology
d) Passive technology

View Answer

Answer: a [Reason:] First generation cellular and cordless telephone networks are based on analog technology. All first generation cellular systems use FM modulation, and cordless telephones use a single base station to communicate with a single portable terminal.

2. Which of the following is true for first generation wireless systems?
a) Efficient
b) Digital technology
c) High data rate
d) Low rate

View Answer

Answer: d [Reason:] First generation wireless systems provide analog speech and inefficient, low rate, data transmission between the base station and mobile user.

3. Which of the following network protocol is used by US cellular carriers to automatically accommodate subscribers who roam into their coverage regions?
a) IS-36
b) IS-121
c) IS-41
d) IS-14

View Answer

Answer: c [Reason:] US cellular carriers implemented the network protocol standard IS-41 to allow different cellular systems to automatically accommodate subscribers who roam into their coverage region.

4. IS-41 does not rely on autonomous registration. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] IS-41 relies on a feature of AMPS called autonomous registration. Autonomous registration is a process by which a mobile notifies a serving MSC of its presence and location.

5. MSC distinguishes home users from roaming users based on MIN. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] The MSC is able to distinguish home users from roaming users based on the MIN of each active user, and maintains a real time user list in the home location register (HLR) and visitor location register (VLR).

6. The visited system creates a _____ record for each roamer and notifies home system to update ____
a) HLR, VLR
b) VLR, MIN
c) MIN, ESN
d) VLR, HLR

View Answer

Answer: d [Reason:] The visited system creates a VLR record for each new roamer and notifies the home system via IS-41 so it can update its own HLR. IS-41 allows the MSCs of neighboring systems to automatically handle the registration and location validation of roamers so that users no longer need to manually register as they travel.

7. Which of the following is not an example of second generation wireless networks?
a) GSM
b) CT2
c) AMPS
d) PACS

View Answer

Answer: c [Reason:] AMPS is an example of first generation wireless networks. Second generation wireless systems employ digital modulation and advanced call processing capabilities. Example includes GSM, CT2, PACS and DECT.

8. In second generation wireless networks, the handoff process is called _____
a) MAHO
b) Soft handoff
c) Hard handoff
d) Inter system handoff

View Answer

Answer: a [Reason:] In second generation wireless networks, the handoff process is mobile controlled and is known as mobile assisted handoff (MAHO). The mobile units in these networks perform several other functions not performed by first generation subscriber units.

9. _____ is an example of second generation cordless telephone standard which allows each cordless phone to communicate with any number of base stations.
a) PACS
b) CT2
c) GSM
d) DECT

View Answer

Answer: d [Reason:] DECT is an example of second generation cordless telephone standard which allows each cordless phone to communicate with any number of base stations. In DECT, the base stations have greater control in terms of switching, signalling, and controlling handoffs.

10. In PACS/ WACS, the BSC is called a ______
a) Radio port control unit
b) HLR
c) VLR
d) MIN

View Answer

Answer: a [Reason:] In PACS/ WACS, the BSC is called a radio port control unit. This architectural change has allowed the data interface between the base station controller and the MSC to be standardized.

11. FPLMTS is recently known by the name ______
a) GSM
b) ISDN
c) IMTS-2000
d) DECT

View Answer

Answer: c [Reason:] FPLMTS (Future Public Land Mobile Telecommunication Systems) is more recently been called International Mobile Telecommunication (IMT-2000). It implies emerging third generation wireless systems for hand held devices.

Communications MCQ Set 2

1. Equalization techniques can be categorised into _______ and ______ techniques.
a) Linear, non linear
b) Active, passive
c) Direct, indirect
d) Slow, fast

View Answer

Answer: a [Reason:] Equalization techniques can be classified into linear and non linear techniques. These categories are determined from how the output of a adaptive equalizer is used for subsequent control of the equalizer.

2. Equalization is linear, if an analog signal is fed back to change the subsequent outputs of the equalizer. Sate whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] If the analog signal is not used in the feedback path to adapt the equalizer, the equalization is linear. On the other hand, if it is fed back to change the subsequent ouputs of the equalizer, the equalization is non-linear.

3. In the context of equalizers, LTE stands for ________
a) Long transversal equalizer
b) Least time-varying equalizer
c) Linear transversal equalizer
d) Linear time-varying equalizer

View Answer

Answer: c [Reason:] The most common equalizer structure used for equalization is linear transveral equalizer (LTE). It is made up of tapped delay lines, with the tappings speed a symbol period apart.

4. Which of the following is not a characteristic of FIR filter?
a) Many zeroes
b) Poles only at z=0
c) Transfer function is a polynomial of z-1
d) Many poles

View Answer

Answer: d [Reason:] Finite impulse response filter (FIR) has many zeroes but poles only at z=0. The transfer function of the filter is a polynomial of z-1. It is also referred to as transversal filter.

5. Which of the following is not an advantage of lattice equalizer?
a) Simple structure
b) Numerical stability
c) Faster convergence
d) Dynamic assignment

View Answer

Answer: a [Reason:] The structure of lattice equalizer is more complicated than a linear transversal equalizer. But, numerical stability and faster convergence are two advantage of laatic equalizer. Also, its unique structure allows dynamic assignment of the most effective length of lattice equalizer.

6. Non-linear equalizers are used in applications where channel distortion is not severe.
a) True
b) False

View Answer

Answer: b [Reason:] Non-linear equalizers are used in applications where the channel distortion is too severe for a linear equalizer to handle. They are most commonly used in practical wireless communication.

7. Which of the following is not a non-linear equalization technique?
a) Decision feedback equalization
b) Maximum likelihood symbol detection
c) Minimum square error detection
d) Maximum likelihood sequence detection

View Answer

Answer: c [Reason:] Decision feedback equalization, maximum likelihood symbol detection and maximum likelihood sequence detection offers non-linear equalization. They offer improvements over linear equalization techniques and are used in most 2G and 3G systems.

8. For a distorted channel, LTE performance is superior to DFE. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] LTE is well behaved when channel spectrum is comparatively flat. But if the channel is severely distorted or exhibits null in the spectrum, the performance of LTE deteriorates and MSE of DFE is better than LTE.

9. Which of the following does not hold true for MLSE?
a) Minimizes probability of sequence error
b) Require knowledge of channel characteristics
c) Requires the statistical distribution of noise
d) Operates on continuous time signal

View Answer

Answer: d [Reason:] Matched filter operates on the continuous time signal, whereas maximum likelihood sequence estimation (MLSE) equalizer and channel estimator rely on discretized samples. MLSE is optimal in the sense that it minimizes the probability of sequence error.

10. MLSE decodes each received signal by itself.
a) True
b) False

View Answer

Answer: b [Reason:] Rather than decoding each received signal by itself, MLSE tests all possible data sequences by using a channel impulse response simulator within the algorithm. It chooses the data sequence with maximum probability as the output.

Communications MCQ Set 3

1. Empirical approach is based on fitting curve or analytical expressions. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] The empirical approach is based on fitting curves or analytical expressions that recreate a set of measured data. This has the advantage of implicitly taking into account all propagation factors, both known and unknown through actual field measurements.

2. Which of the following is not a practical path loss estimation technique?
a) Log distance path loss model
b) Log normal shadowing
c) Determination of percentage of coverage area
d) Hata model

View Answer

Answer: a [Reason:] Log normal shadowing, log distance path loss model and determination of percentage of coverage area are practical pat loss estimation techniques. Hata model is only valid for exterior environment.

3. Average received signal power decreases __________ with distance.
a) Exponentially
b) Logarithmically
c) Two times
d) Four times

View Answer

Answer: b [Reason:] Both theoretical and measurement based propagation models indicate that average received signal power decreases logarithmically with distance. It is valid for both outdoor and indoor channels.

4. What does path loss exponent indicates?
a) Rate at which path loss decreases with distance
b) Rate at which path loss increases with distance
c) Rate at which path loss decreases with power density
d) Rate at which path loss increases with power density

View Answer

Answer: b [Reason:] The average large scale path loss for an arbitrary T-R separation is expressed as a function of distance by using a path loss exponent, n. It indicates the rate at which the path loss increases with distance.

5. The reference distance should not be in the far field of the antenna. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] It is important to select a free space reference distance that is appropriate for the propagation environment. The reference distance should always be in the far field of the antenna so that near field effects do not alter the reference path loss.

6. Which distribution describes the shadowing effect?
a) Log normal distribution
b) Nakagami distribution
c) Cauchy distribution
d) Rayleigh distribution

View Answer

Answer: a [Reason:] Log normal distribution describes the random shadowing effects. It occurs over a large number of measurement locations which have the same T-R separation, but have different clutter on the propagation path.

7. Log normal shadowing is a phenomenon that occurs with same T-R separation having same level clutter on the propagation path. State True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Log normal shadowing occurs over a large number of measurement locations which have the same T-R separation, but have different levels of clutter on the propagation path. It follows log normal distribution.

8. Log normal shadowing implies that measured signal levels at specific T-R separation have ______ distribution when signal levels have values in dB units.
a) Rayleigh
b) Gamma
c) Gaussian
d) Nakagami

View Answer

Answer: c [Reason:] Log normal shadowing implies that measured signal levels at a specific T-R separation have Gaussian (Normal) distribution. It is about the distance dependent mean of 4.68 where the signal levels have values in dB units.

9. A link budget is accounting of all __________
a) Gain and losses from the transmitter
b) Power transmitted by transmitter
c) Power received by receiver
d) Power transmitted and received

View Answer

Answer: a [Reason:] A link budget is accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide etc.) to the receiver in a telecommunication system. It accounts for the attenuation of the transmitted signal due to propagation, as well as the antenna gains and miscellaneous losses.

10. Antenna’s efficiency is given by the ratio of __________
a) Losses
b) Physical aperture to effective aperture
c) Signal power to noise power
d) Effective aperture to physical aperture

View Answer

Answer: a [Reason:] The larger the antenna aperture the larger is the resulting signal power density in the desired direction. The ratio of effective aperture to physical aperture is the antenna’s efficiency.

Communications MCQ Set 4

1. Which of the following technology is mainly designed for indoor coverage?
a) Femtocell network
b) 3GPP
c) LTE
d) AMPS

View Answer

Answer: a [Reason:] Femtocell Network is a small-size Macro cell network designed for better indoor coverage. It began attracting attention from both industry and academy in late 2007.

2. Coverage of Femtocell Network is much larger than a regular Macro cell Network. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] The “femto” means 10-15. Coverage of Femtocell Network is much smaller than a regular Macro cell Network that is why this name is given. Femtocell Network, installed by end users at home or in an office environment.

3. Which of the following is not a component of Femtocell network?
a) F-BS
b) Internet link
c) FGW
d) BSC

View Answer

Answer: d [Reason:] Similar to UMTS Terrestrial Radio Access Network (UTRAN) architecture, the Femtocell Network consists of three components: Femtocell Base Stations (F-BS), Internet Link, and Femtocell Gateway (FGW).

4. Which of the following is not true for Femtocell base stations?
a) Short range
b) Low power
c) High cost
d) Wireless handsets

View Answer

Answer: c [Reason:] Femtocell Base Stations (F-BSs) are short-range, low-cost, low-power indoor devices to provide service for wireless handsets. F-BS, which looks like WLAN Access Point (AP), is a small device with at least two wireless and internet interfaces.

5. Any existing wireless telecommunication standard cannot be used at F-BS wireless interface. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Wireless interface provides wireless radio access to Femtocell MSs. Any existing wireless telecommunication standard, such as UMTS/ CDMA200/ WIMAX/ LTE/ EV-DO, can be used at the F-BS wireless interfaces.

6. ________ acts as a gateway between the Internet and communication network.
a) F-BS
b) Internet link
c) FGW
d) BSC

View Answer

Answer: c [Reason:] Femtocell Gateway (FGW) is a service provider’s device that acts as a gateway between the Internet and the communication network. One side of FGW connects a large number of F-BSs via broadband Internet, and the other side of FGW is connected to the telephony core network.

7. Femtocell network has improved seamless coverage and enhanced capacity. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] Femtocell Network is a so-called “double-win” strategy that brings benefits to both cellular users and cellular providers. It provides improved seamless coverage and enhanced capacity for cellular users.

8. In _________ all cellular users belong to open subscribers group (OSG) and can access F-BS unconditionally.
a) Closed access mode
b) Open access mode
c) Hybrid Access mode
d) Zero access mode

View Answer

Answer: b [Reason:] In open access mode, all cellular users belong to open subscribers group (OSG) and can access F-BS unconditionally. Several cellular service providers have plans to deploy F-BS for better service quality to cover public hole areas.

9. In _______ a closed subscribers group (CSG) is set by F-BS owner to allow only small portion of cellular users to be served in the Femtocell Network.
a) Closed access mode
b) Open access mode
c) Hybrid Access mode
d) Zero access mode

View Answer

Answer: a [Reason:] In closed access mode, a closed subscribers group (CSG) is set by F-BS owner to allow only small portion of cellular users to be served in the Femtocell Network. For example, people can install F-BS in their house and only household members can access F-BS to attain better service.

10. Femtocell Network has the capability to help Macro cell Network achieve seamless coverage. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] Femtocell Network has the capability to help Macro cell Network achieve seamless coverage. It can attain higher network capacity by transmitting over an Internet link.

Communications MCQ Set 5

1. The mechanism behind electromagnetic wave propagation cannot be attributed to _____
a) Reflection
b) Diffraction
c) Scattering
d) Sectoring

View Answer

Answer: d [Reason:] The mechanisms behind electromagnetic wave propagation are diverse. They can be greatly attributed to reflection, diffraction and scattering. Due to multiple reflections from various objects, the electromagnetic waves travel along different paths of varying lengths.

2. The propagation model that estimates radio coverage of a transmitter is called ___________
a) Large scale propagation model
b) Small scale propagation model
c) Fading model
d) Okumura model

View Answer

Answer: a [Reason:] Large scale propagation model are useful in estimating the radio coverage area of a transmitter. They can predict the mean signal strength for an arbitrary transmitter- receiver (T-R) separation distance. They characterize signal strength over large T-R separation distances.

3. Propagation model that characterize rapid fluctuation is called _________
a) Hata model
b) Fading model
c) Large scale propagation model
d) Okumura model

View Answer

Answer: b [Reason:] Fading models characterize the rapid fluctuations of the received signal strength over very short travel distance (a few wavelengths) or shot time durations (on the order of seconds).

4. Small scale propagation model is also known as _______
a) Fading model
b) Micro scale propagation model
c) Okumura model
d) Hata model

View Answer

Answer: a [Reason:] Small scale propagation model is also called fading model. Fading model characterize the rapid fluctuations of the received signal strength over very short distance of a few wavelengths or short time duration. The propagation models are used to estimate the performance of wireless channels.

5. Free space propagation model is to predict ______
a) Received signal strength
b) Transmitted power
c) Gain of transmitter
d) Gain of receiver

View Answer

Answer: a [Reason:] Free space propagation model predicts the received signal strength when there is an unobstructed line of sight path between transmitter and receiver. It assumes the ideal propagation condition that the environment is empty between the transmitter and receiver.

6. Which of the following do not undergo free space propagation?
a) Satellite communication system
b) Microwave line of sight radio links
c) Wireless line of sight radio links
d) Wired telephone systems

View Answer

Answer: d [Reason:] EM signals when traveling through wireless channels experience fading effects due to various effects. But in some cases the transmission is with no obstruction and direct line of sight such as in satellite communication, microwave and wireless line of sight radio links.

7. The free space model predicts that received signal decays as a function of _____
a) Gain of transmitter antenna
b) T-R separation
c) Power of transmitter antenna
d) Effective aperture of the antenna

View Answer

Answer: b [Reason:] As with most large scale radio wave propagation models, the free space model predicts that received signal decays as a function of the T-R separation distance raised to some power. Often it is given as a function of negative square root of the distance.

8. Relation between gain and effective aperture is given by ______
a) G=(4πAe)/λ2
b) G=(4π λ2)/ Ae
c) G=4πAe
d) G=Ae/λ2

View Answer

Answer: a [Reason:] The gain of the antenna is proportional to effective aperture area. Therefore, antennas with large effective apertures are high gain antennas and have small angular beam widths. Most of their power is radiated in a narrow beam in one direction, and little in other directions .

9. Relation between wavelength and carrier frequency is _____
a) λ=c/f
b) λ=c*f
c) λ=f/c
d) λ=1/f

View Answer

Answer: a [Reason:] Wavelength is inversely proportional to carrier frequency. For electromagnetic radiation in free space, wavelength is a ratio of speed of light (c) and carrier frequency (f). Speed of light is 3*108 m/s. The unit for wavelength is meters.

10. Which of the following antenna radiates power with unit gain uniformly in all directions?
a) Directional antenna
b) Dipole antenna
c) Isotropic antenna
d) Loop antenna

View Answer

Answer: c [Reason:] Isotropic antenna radiates the power with unit gain uniformly in all directions. It is an ideal antenna. From practical point of view, there is no actual isotropic antenna. But, an isotropic antenna is often used as a reference antenna for the antenna gain.

11. EIRP is abbreviated as __________
a) Effective isotropic radiated power
b) Effective isotropic radio power
c) Effective and immediate radiated power
d) Effective and immediate ratio of power

View Answer

Answer: a [Reason:] EIRP stands for Effective Isotropic Radiated Power. It is the amount of power that a theoretical isotropic antenna would emit to produce the peak power density observed in the direction of maximum antenna gain. EIRP also takes into account the losses in transmission line and connectors and includes the gain of the antenna.

12. Path loss in free space model is defined as difference of ________
a) Effective transmitted power and gain
b) Effective received power and distance between T-R
c) Gain and received power
d) Effective transmitter power and receiver power

View Answer

Answer: d [Reason:] I Path loss is defined as difference of effective transmitter power and receiver power. Free-space path loss is the loss in signal strength of an electromagnetic wave that would result from a line-of-sight path through free space, with no obstacles nearby to cause reflection or diffraction.

13. Far field region is also known as _________
a) Near field region
b) Fraunhofer region
c) Erlang region
d) Fresnel region

View Answer

Answer: b [Reason:] The far field is the region far from the antenna. In this region, the radiation pattern does not change shape with distance. Also, this region is dominated by radiated fields, with the E- and H-fields orthogonal to each other and the direction of propagation as with plane waves.

14. Fraunhofer distance is given by _____
a) 2D2/λ
b) 2D/λ
c) D/λ
d) 2D/λ2

View Answer

Answer: a [Reason:] Fraunhofer distance, also known as far field distance is inversely proportional to wavelength. It depends on the largest physical dimension of the antennal (D). This distance basically denotes the boundary between far field and near field region.

15. Which of the following is called an ideal antenna?
a) Dipole antenna
b) Directional antenna
c) Isotropic antenna
d) Loop antenna

View Answer

Answer: c [Reason:] Isotropic antenna is an ideal antenna that directs the power uniformly in all directions. It is a theoretical point source of electromagnetic. It is practically not possible. It is mainly used as a hypothetical antenna to measure the gain.