Category: Wireless & Mobile Communications Objective Questions

Wireless & Mobile Communications Multiple Choice Questions on “Rayleigh and Ricean Distribution”.

1. Which of the following distribution is used for describing statistical time varying nature of received envelope of multipath component?
a) Log normal distribution
b) Levy distribution
c) Rayleigh distribution
d) Gaussian distribution
Answer: c
Clarification: Rayleigh distribution is the most common distribution for statistical modelling. It is used to describe the statistical time varying nature of the received envelope of a flat fading signal. It also describes the envelope of an individual multipath component.

2. Envelope of the sum of two quadrature Gaussian noise signal obeys _________ distribution.
a) Rayleigh
b) Inverse Gaussian
c) Nakagami
d) Gamma
Answer: a
Clarification: It is well known that the envelope of the sum of two quadrature Gaussian noise signal obeys Rayleigh distribution. This fading distribution could be applied to any scenario where there is no line of sight path between transmitter and receiver antennas.

3. For a Rayleigh fading signal, mean and median differ by _______
a) 2 dB
b) 10 dB
c) 0.55 dB
d) 100 dB
Answer: c
Clarification: The mean and median differ by only 0.55 dB in a Rayleigh fading signal. The differences between the rms values and the other two values are higher.

4. It is easy to compare different fading distributions using mean values instead of median values.
a) True
b) False
Answer: b
Clarification: By using median values instead of mean values, it is easy to compare different fading distributions which may have widely varying means. Median is used in practice since fading data is measured in the field and a particular distribution cannot be assumed.

5. For a nonfading signal component present, the small scale fading envelope distribution is ____________
a) Rayleigh
b) Gaussian
c) Log normal
d) Ricean
Answer: d
Clarification: The small scale fading envelope is Ricean when there is a dominant stationary (nonfading) signal component, such as line of sight propagation path. In such a situation, random multipath components arriving at different angles are superimposed on a stationary dominant signal.

6. Ricean distribution degenerates to ________ distribution when the dominant component fades away.
a) Log normal
b) Gamma
c) Rayleigh
d) Gaussian
Answer: c
Clarification: Ricean distribution degenerates to Rayleigh distribution when the dominant component fades away. As the dominant signal becomes weaker, the composite signal resembles a noise signal which has an envelope that is Rayleigh.

7. The envelope of a bandpass noise is __________
a) Uniformly distributed
b) Rayleigh
c) Ricean
d) Gaussian
Answer: b
Clarification: The envelope of only bandpass noise is Rayleigh distribution. Rayleigh distribution is a continuous probability density function for positive random variables.

8. The envelope of a sinusoid plus bandpass noise has __________
a) Uniformly distributed
b) Rayleigh
c) Ricean
d) Gaussian
Answer: c
Clarification: The envelope of a sinusoid plus bandpass noise has Ricean distribution. In probability theory, Ricean distribution is the probability distribution which has magnitude of a circular bivariate normal random variable with potentially non-zero mean.

9. What do you call an attenuation that occurs over many different wavelengths of the carrier?
a) Rayleigh fading
b) Ricean fading
c) Wavelength fading
d) Slow fading
Answer: d
Clarification: Slow fading does not vary quickly with the frequency. It originates due to effect of mobility. Slow fading is the result of signal path change due to shadowing and obstructions such as tree or buildings etc.

10. Which of the reception problems below that is not due to multipath?
a) Delayed spreading
b) Rayleigh fading
c) Random Doppler shift
d) Slow fading
Answer: d
Clarification: Slow fading arises when the coherence time of the channel is large relative to the delay requirement of the application. Slow fading is caused by events such as shadowing, where a large obstruction such as a hill or large building obscures the main signal path between the transmitter and the receiver.

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Wireless & Mobile Communications Multiple Choice Questions on “Diversity Techniques”.

1. Diversity requires a training sequence.
a) True
b) False
Answer: b
Clarification: Unlike equalization, diversity requires no training overhead since a training sequence is not required by the transmitter. Diversity is a powerful communication receiver technique that provides wireless link improvement at a relatively low cost.

2. Diversity decisions are made by ____________
a) Receiver
b) Transmitter
c) Channel
d) Adaptive algorithms
Answer: a
Clarification: In virtually all applications, diversity decisions are made by the receiver and are unknown to the transmitter. Diversity exploits the random nature of radio propagation by finding independent signal paths for communication.

3. Small scale fades are characterized by ____________ amplitude fluctuations.
a) Large
b) Small
c) Rapid
d) Slow
Answer: c
Clarification: Small scale fades are characterized by deep and rapid fluctuations. They occur as the mobile system moves over distances of just a few wavelengths. These fades are caused by multiple reflections from the surrounding in the vicinity of the mobile.

4. ____________ is used to prevent deep fade for rapidly varying channel.
a) Modulation
b) Demodulation
c) Macroscopic diversity technique
d) Microscopic diversity technique
Answer: d
Clarification: In order to prevent deep fades from occurring, microscopic diversity techniques can exploit the rapidly changing signal. By selecting the best signal at all times, a receiver can mitigate small scale fading effects.

5. Large scale fading can be mitigated with the help of _________
a) Modulation
b) Demodulation
c) Macroscopic diversity technique
d) Microscopic diversity technique
Answer: c
Clarification: Large scale fading is mitigated with macroscopic diversity techniques. It is done by selecting a base station which is not shadowed when others are, the mobile can improve substantially the average signal to noise ratio.

6. Space diversity s also known as ________
a) Antenna diversity
b) Time diversity
c) Frequency diversity
d) Polarization diversity
Answer: a
Clarification: Space diversity is also known as antenna diversity. It is one of the popular forms of diversity used in wireless communications. Signals received from the spatially separated antenna on the mobile would have essentially uncorrelated envelopes for antenna separation.

7. Which of the following is not a category of space diversity technique?
a) Selection diversity
b) Time diversity
c) Feedback diversity
d) Equal gain diversity
Answer: b
Clarification: Space diversity reception methods can be classified into four categories. They are selection diversity, feedback diversity, maximal ratio combining and equal gain diversity.

8. In selection diversity, the gain of each diversity branch provides different SNR.
a) True
b) False
Answer: b
Clarification: Selection diversity uses m demodulators to provide m diversity branches. Their gain is adjusted to provide the same average SNR for each branch.

9. Polarization diversity uses the ________ as the diversity element.
a) Modulation index
b) Carrier frequency
c) Reflection coefficient
d) Coherence time
Answer: c
Clarification: Decorrelation of the signal in each polarization is caused by multiple reflections in the channel between mobile and base station antenna. Reflection coefficient for each polarization is different, which results in different amplitudes and phases for each reflection.

10. Which of the factor does not determine the correlation coefficient?
a) Polarization angle
b) Cross polarization discrimination
c) Offset angle from the main beam direction
d) Coherence time
Answer: d
Clarification: The correlation coefficient is determined by three factors, polarization angle, offset angle from the main beam direction of the diversity antenna, and the cross polarization discrimination. The correlation coefficient generally becomes higher as offset angle becomes large.

11. Frequency diversity is implemented by transmitting information on more than one ___________
a) Carrier frequency
b) Amplitude
c) Phase
d) Modulation scheme
Answer: a
Clarification: Frequency diversity is implemented by transmitting information on more than one carrier frequency. Frequency diversity is often employed in microwave line of sight links which carry several channels in frequency division multiplex mode.

12. Frequency diversity uses ________ as a diversity element.
a) Correlation coefficient
b) Coherence time
c) Coherence bandwidth
d) SNR
Answer: c
Clarification: The rationale behind the frequency diversity is that frequencies separated by more than the coherence bandwidth of the channel will be uncorrelated. Thus, they will not experience the same fade.

13. Frequency diversity is good for low traffic conditions.
a) True
b) False
Answer: b
Clarification: Frequency diversity is not good for low traffic conditions. This technique has a disadvantage that it not only requires spare bandwidth but also requires that there be as many receivers as there are channels used for frequency diversity. However, for critical traffic, the expense may be justified.

14. Time diversity repeatedly transmits information at time spacings that exceed ___________
a) Coherence bandwidth
b) Dwell time
c) Run time
d) Coherence time
Answer: d
Clarification: Time diversity repeatedly transmits information at time spacings that exceed coherence time of the channel. Thus, multiple repetitions of the signal will be received with independent fading conditions, thereby providing for diversity.

15. In maximal ratio combining, the output SNR is equal to __________
a) Mean of all individual SNRs
b) Maximum of all SNRs
c) Sum of individual SNR
d) Minimum of all SNRs
Answer: c
Clarification: Maximal ratio combining produces an output SNR equal to the sum of the individual SNRs. Thus, it has the advantage of producing an output with an acceptable SNR even when none of the individual signals are themselves acceptable.

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Wireless & Mobile Communications Multiple Choice Questions on “Wireless and Fixed Telephone Networks”.

1. In a wireless communication, base station is connected to central hub called _______
a) PSTN
b) MSC
c) CO
d) PBX
Answer: b
Clarification: To provide wireless communication within a particular geographic region, an integrated network of base stations must be deployed to provide sufficient radio coverage to all mobile users. The base station, in turn must be connected to a central hub called MSC (mobile switching center).

2. PSTN stands for ________
a) Public switched telephone network
b) Personal switched telephone network
c) Personal switched telephone node
d) Public switched telephone node
Answer: a
Clarification: PSTN stands for public switched telephone network. The PSTN forms the global telecommunication grid which connects conventional telephone centers with MSCs throughout the world.

3. MSCs provide connectivity between PSTN and the base stations.
a) True
b) False
Answer: a
Clarification: The MSC provide connectivity between the public switched telephone network (PSTN) and the numerous base stations. It ultimately provides connectivity between all of the wireless subscribers in the system.

4. Communication protocol, CAI stands for ___________
a) Common air interchange
b) Control air interchange
c) Common air interface
d) Control air interchange
Answer: c
Clarification: To connect mobile subscribers to the base stations, radio links are established using a carefully defined communication protocol called common air interface (CAI) which in essence is a precisely defined handshake communication protocol.

5. At the base station, the air interface portion of mobile transmission is passed to MSC.
a) True
b) False
Answer: b
Clarification: At the base station, the air interface portion (i.e., signalling and synchronization data) of the mobile transmission is discarded, and the remaining voice traffic is paased along to the MSC on fixed networks.

6. PSTN is ___________ and wireless networks are ________
a) Highly dynamic, virtually static
b) Static, virtually static
c) Highly dynamic, virtually dynamic
d) Virtually static, highly dynamic
Answer: d
Clarification: The network configurations in the PSTN are virtually static, since the network connections may only be changed when a subscriber changes residence. Wireless networks are highly dynamic with the network configuration being rearranged everytime a new subscriber moves into the coverage region of a different base station.

7. In public switched telephone network, LATA stands for ______
a) Local access and transport area
b) Land area and transport area
c) Local access and telephone access
d) Local area and telephone access
Answer: a
Clarification: In public switched telephone network, LATA stands for Local access and transport area. LATA is a city or a geographic grouping of towns in PSTN.

8. LATAs are connected by a company called _________
a) Land exchange carrier
b) Local exchange carrier
c) Local control exchange
d) Land area exchange
Answer: b
Clarification: Surrounding LATAs are connected by a company called a local exchange carrier (LEC). A LEC is a company that provides telephone services and may be a local telephone company.

9. A long distance telephone company that collects toll is called _________
a) LATA
b) LEC
c) PSTN
d) IXC
Answer: d
Clarification: A long distance telephone company collects toll fees to provide connections between different LATAs over its long distance network. These companies are referred to as interexchange carriers (IXCs).

10. Wireless networks are extremely hostile and random nature of radio channel.
a) True
b) False
Answer: a
Clarification: A problem unique to wireless networks is the extremely hostile and random nature of the radio channel, and since users may request service from any physical location while traveling over a wide range of velocities.

11. The technique for separate but parallel signalling channel is called ________
a) Common channel signalling
b) Forward channel signalling
c) Reverse channel signalling
d) Separate channel signalling
Answer: a
Clarification: During the mid 1980s, the PSTN was transformed into two parallel networks- one dedicated to user traffic, and one dedicated to call signalling traffic. This technique is called common channel signalling.

12. In North America, the cellular telephone signalling network uses _______
a) SS7
b) IXC
c) IS-41
d) PSTN
Answer: a
Clarification: In North America, the cellular telephone signalling network uses No. 7 Signalling System (SS7), and each MSC uses the IS-41 protocol to communicate with other MSCs on the continent.

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Wireless & Mobile Communications Multiple Choice Questions on “Paging System”.

1. IPv6 has a larger address space of _________
a) 2¹⁶
b) 2¹²⁸
c) 2³²
d) 2⁸
Answer: b
Clarification: The main advantage of IPv6 over IPv4 is its larger address space. The length of an IPv6 address is 128 bits, compared with 32 bits in IPv4. The address space therefore has 2¹²⁸ or approximately 3.4×10³⁸ addresses.

2. Three strategies used to handle transition from version 4 to version 6 are dual-stack, tunneling and ________
a) Header Switching
b) Header Translation
c) Header Transfer
d) Header Transmission
Answer: b
Clarification: Three strategies used to handle transition from version 4 to version 6 are dual-stack, tunneling and header translation. Header translation techniques are more complicated than IPv4 NAT because the protocols have different header formats.

3. MTU stands for _________
a) Minimum Transfer Unit
b) Maximum Transfer Unit
c) Maximum Transport Unit
d) Maximum Transmission Unit
Answer: d
Clarification: In computer networking, the maximum transmission unit (MTU) is the size of the largest network layer protocol data unit that can be communicated in a single network transaction.

4. In IPv6, real-time audio or video, particularly in digital form, requires resources such as __________
a) Fixed Bandwidth
b) Variable Bandwidth
c) High Bandwidth
d) Low Bandwidth
Answer: c
Clarification: In IPv6, real-time audio or video, particularly in digital form, requires resources such as high bandwidth, large buffers, long processing times, and so on. A process can make a reservation for these resources beforehand to guarantee that real time data will not be delayed.

5. In practical IPv6 application, a technology encapsulates IPv6 packets inside IPv4 packets, this technology is called _______
a) Tunneling
b) Hashing
c) Routing
d) NAT
Answer: a
Clarification: IPv6 tunneling enables IPv6 hosts and routers to connect with other IPv6 hosts and routers over the existing IPv4 Internet. The main purpose of IPv6 tunneling is to deploy IPv6 as well as maintain compatibility with large existing base of IPv4 hosts and routers.

6. Which one of the following descriptions about IPv6 is correct?
a) Addresses are not hierarchical and are assigned at random
b) Broadcasts have been eliminated and replaced with multicasts
c) There are 2.7 billion available addresses
d) An interface can only be configured with one IPv6 address
Answer: b
Clarification: In IPv6, there’s no longer any broadcast, sending one packet to a large number of unspecified hosts. There’s only multicast, unicast and anycast. In IPv6 all nodes are required to support multicast.

7. The header length of an IPv6 datagram is ___________
a) 10bytes
b) 25bytes
c) 30bytes
d) 40bytes
Answer: d
Clarification: IPv6 datagram has fixed header length of 40bytes. It results in faster processing of the datagram. Fixed length IPv6 header allows the routers to process the IPv6 datagram packets more efficiently.

8. In the IPv6 header, the traffic class field is similar to which field in the IPv4 header?
a) Fragmentation field
b) Fast switching
c) TOS field
d) Option field
Answer: c
Clarification: This field enables to have different types of IP datagram. In an IPv6 packet, the Traffic Class byte is used in the same way as the ToS byte in an IPv4 packet. A ToS/Traffic Class byte includes a DSCP (Differentiated Services Codepoint) and precedence bits.

9. Which are the features present in IPv4 but not in IPv6?
a) Fragmentation
b) Header checksum
c) Options
d) All of the mentioned
Answer: d
Clarification: All the features are only present in IPv4 and not IPv6. IPv6 no longer has a header checksum to protect the IP header, meaning that when a packet header is corrupted by transmission errors, the packet is very likely to be delivered incorrectly.

10. IPv6 is designed to allow extension of the _________
a) Protocol
b) Dataset
c) Headers
d) Routes
Answer: a
Clarification: IPv6 is designed to allow the extension of the protocol if required by new technologies or applications. IPv6 uses a new header format in which options are separated from the base header and inserted, when needed, between the base header and upper-layer data.

11. In IPv6, base header can be followed by, up to _________
a) Six Extension Layers
b) Six Extension Headers
c) Eight Extension headers
d) Eight Extension layers
Answer: b
Clarification: The length of the base header is 40 bytes. However, to give more functionality to the IP datagram, the base header can be followed by up to six extension headers.

12. In an IPv6 datagram, M bit is 0, value of HLEN is 5, value of total length is 200 and offset value is ___________
a) 400
b) 350
c) 300
d) 200
Answer: d
Clarification: In an IPv6 datagram, M bit is 0, value of HLEN is 5, the value of total length is 200 and offset value is 200. If the M bit is 0, it means there are no more fragments, the fragment is the last name.

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Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) on “Interference and System Capacity”.

1. Which of the following is not a source of interference?
a) Base station in a different cluster
b) Another mobile in same cell
c) A call in progress in neighbouring cell
d) Any BS operating on same frequency
Answer: a
Clarification: Interference is a major limiting factor in the performance of cellular radio systems. Sources of interference includes another mobile in the same cell, a call in progress in neighbouring cell, other base stations operating in the same frequency band, or any non-cellular system which inadvertently leaks energy into the cellular frequency band.

2. Interference on voice channels causes _______
a) Blocked calls
b) Cross talk
c) Queuing
d) Missed calls
Answer: b
Clarification: Interference on voice channels causes crass talk. Here, the subscriber hears interference in the background due to an undesired transmission.

3. Interference in control channel leads to ________
a) Cross talk
b) Queuing
c) Blocked calls
d) Voice traffic
Answer: c
Clarification: On control channels, interference leads to missed and blocked calls. This happens due to errors in the digital signalling.

4. Interference is more severe in rural areas.
a) True
b) False
Answer: a
Clarification: Interference is more severe in rural areas. It happens due to the greater RF noise floor and the large number of base stations and mobiles.

5. What are co-channel cells?
a) Cells having different base stations
b) Cells using different frequency
c) Cells using adjacent frequency
d) Cells using same frequency
Answer: d
Clarification: Due to frequency reuse concept, there are several cells that use the same set of frequencies. These cells are called co-channel cells. And the interference between these cells is called co-channel interference.

6. Co-channel interference is a function of _________
a) Radius of cell
b) Transmitted power
c) Received power
d) Frequency of mobile user
Answer: a
Clarification: This is the case when the size of each cell is approximately the same and the base stations transmit the same power. Co-channel interference ratio is independent of the transmitted power and becomes a function of the radius of the cell ® and the distance between centers of the nearest co channel cell (D).

7. Co-channel reuse ratio is define by _________
a) Q=D*R
b) Q=D/R
c) Q=D^R
d) Q=1/R
Answer: b
Clarification: Co-channel reuse ratio is defined by Q=D/R. By increasing the ratio of D/R, the spatial separation between co-channel cells relative to the coverage distance of a cell is increased. Thus, interference I reduced from improved isolation of RF energy from the co-channel cells.

8. Co-channel ratio in terms of cluster size is defined as _________
a) (sqrt{(3N)})
b) N
c) 3N
d) √N
Answer: a
Clarification: Co-channel reuse is defined using (sqrt{(3N)}). A small value of Q provides larger capacity since the cluster size N is small. However, a large value of Q improves the transmission quality, due to smaller level of co-channel interference.

9. What is the cluster size for CDMA?
a) N=10
b) N=100
c) N=1
d) N=50
Answer: c
Clarification: CDMA systems have a cluster size of N=1.Therefore, frequency reuse is not as difficult as for TDMA or first generation cellular systems.

10. What is breathing cell effect?
a) Fixed coverage region
b) Dynamic and time varying coverage region
c) Large coverage region
d) Very small coverage region
Answer: b
Clarification: Breathing cell is a concept used by CDMA systems. They had a dynamic, time varying coverage region which varies depending on the instantaneous number of users on the CDMA radio channel.

11. Adjacent channel interference occurs due to _______
a) Power transmitted by Base station
b) MSCs
c) Same frequency of mobile users
d) Imperfect receiver filters
Answer: d
Clarification: Interference resulting from signals which are adjacent in frequency to the desired signal is called adjacent channel interference. It results from imperfect receiver filters which allow nearby frequencies to leak into the passband.

12. Which of the following problem occur due to adjacent channel interference?
a) Blocked calls
b) Cross talk
c) Near-far effect
d) Missed calls
Answer: c
Clarification: One of the main problems with adjacent channel interference is the near-far effect. It occurs when a mobile close to a base station transmits on a channel close to one being used by a weak mobile.

13. In near-far effect, a nearby transmitter captures the __________
a) Receiver of the subscriber
b) Transmitter of the subscriber
c) Nearby MSC
d) Neighbouring base station
Answer: a
Clarification: Near-far effect occurs if an adjacent channel user is transmitting in very close range to a subscriber’s receiver while the receiver attempts to receive a base station on the desired channel. In this effect, a nearby transmitter captures the receiver of the subscriber.

14. Adjacent channel interference can be minimized through _______
a) Changing frequency of base stations
b) Careful filtering and channel assignments
c) Increasing number of base stations
d) Increasing number of control channels
Answer: b
Clarification: Adjacent channel assignment can be minimized through careful filtering and channel assignments. Each cell is given only a fraction of the available channels, a cell need not be assigned channels which are all adjacent in frequency.

15. In dynamic channel assignment, any channel which is being used in one cell can be reassigned simultaneously to another cell in the system at a reasonable distance.
a) True
b) False
Answer: a
Clarification: Dynamic channel assignment (DCA) is one well known solution to the micro cellular channel assignment problem. The dynamic nature of the strategy permits adaptation to spatial and traffic variations while the distribution of control reduces the required computational load.

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Wireless & Mobile Communications test on “Statistical Models for Multipath Fading Channels”.

1. Which of the following is not a statistical models for multipath fading channels?
a) Clarke’s model for flat fading
b) Saleh and Valenzuela indoor statistical model
c) Two ray Rayleigh fading model
d) Faraday model
Answer: d
Clarification: Several multipath models have been suggested to explain the observed statistical nature of a mobile channel. Clarke’s model for flat fading, Saleh and Valenzuela indoor statistical model, two ray Rayleigh fading model are some of the statistical model for multipath fading channels.

2. Who presented the first statistical model for multipath fading channel?
a) Ossana
b) Rayleigh
c) Newton
d) Faraday
Answer: a
Clarification: The first statistical model was presented by Ossana. It was based on interference of wave incident and reflected from the flat sides of randomly located buildings. Ossana model predicts flat fading power spectra that were in agreement with measurements in suburban areas.

3. Clarke’s model assumes a horizontal polarized antenna.
a) True
b) False
Answer: b
Clarification: Clarke developed a model where the statistical characteristics of the electromagnetic fields of the received signal at the mobile are deduced from scattering. Clarke’s model assumes a fixed transmitter with a vertically polarized antenna.

4. A wave that is incident on mobile does not undergo Doppler shift.
a) True
b) False
Answer: b
Clarification: Every wave that is incident on the mobile undergoes a Doppler shift. It is due to the motion of the receiver and it arrives at the receiver at the same time. Therefore, there is no excess delay due to multipath for any of the waves.

5. Which of the following is an important statistics of a Rayleigh fading useful for designing error control codes and diversity schemes?
a) Mobile speed
b) Doppler frequency
c) Level crossing rate (LCR)
d) Power density
Answer: c
Clarification: The level crossing rate (LCR) and average fade duration of a Rayleigh fading signal are important statistics. They are useful for designing error control codes and diversity schemes to be used in mobile communication.

6. The level crossing rate (LCR) is defined as expected rate at which _______ fading envelope crosses a specified level.
a) Rayleigh
b) Saleh
c) Vanezuela
d) Faraday
Answer: a
Clarification: The LCR is defined as the expected rate at which the Rayleigh fading envelop is normalized to the local rms signal level. And it crosses a specified level in a positive going direction.

7. Level crossing rate is a function of _______
a) Power transmitted by base station
b) Power density of receiver
c) Mobile speed
d) Bit error rate
Answer: c
Clarification: The level crossing rate is a function of mobile speed. Because, it is possible to relate the time rate of change of the received signal of the signal level and velocity of the mobile.

8. Clarke’s model considers the multipath time delay.
a) True
b) False
Answer: b
Clarification: Clarke’s model and the statistics for Rayleigh fading are for flat fading conditions. They do not consider multipath time delay.

9. Saleh and Venezuela reported the results of ______ propagation measurements.
a) Indoor
b) Outdoor
c) Air
d) High frequency
Answer: a
Clarification: Saleh and Venezuela reported the results of indoor propagation measurements. The measurements were made between two vertically polarized omnidirectional antennas located on the same floor of a medium sized office building.

10. Saleh and Venezuela show that indoor channel is _______ time varying.
a) Not
b) Very slow
c) Fast
d) Very fast
Answer: b
Clarification: The results obtained by Saleh and Venezuela shows that the indoor channel is quasi static or very slow time varying. It shows that the statistics of the channel impulse response are independent of transmitting and receiving antenna polarization.

11. What is the full form of SIRCIM?
a) Simulation of Indoor Radio Channel Impulse response Model
b) Statistical Indoor Radio Channel for Impulse Model
c) Statistical Impulse Radio Channel for Indoor Model
d) Simulation of Impulse Radio Channel for Indoor Model
Answer: a
Clarification: SIRCIM stands for Simulation of Indoor Radio Channel Impulse response Model. SIRCIM generates realistic samples of small scale indoor channel impulse response measurements.

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