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Communications MCQ Set 1

1. Vocoders analyse the speech signals at ______
a) Transmitter
b) Receiver
c) Channel
d) IF Filter

View Answer

Answer: a [Reason:] Vocoders are a class of speech coding systems. They analyse the speech signal at the transmitter. And then transmit the parameters derived from the analysis.

2. Vocoders _____ the voice at the receiver.
a) Analyse
b) Synthesize
c) Modulate
d) Evaluate

View Answer

Answer: b [Reason:] Vocoders synthesize the voice at the receiver. All vocoder systems attempt to model the speech generation process as a dynamic system and try to quantify certain physical constraints of the system.

3. Vocoders are simple than the waveform coders. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Vocoders are much more complex than the waveform coders. They can achieve very high economy in transmission bit rate, but are less robust.

4. Which of the following is not a vocoding system?
a) Linear predictive coder
b) Channel vocoder
c) Waveform coder
d) Formant vocoder

View Answer

Answer: c [Reason:] Waveform coder is not a vocoding system. LPC (linear predictive coding) is the most popular vocoding system. Other vocoding systems are channel vocoder, formant vocoder, cepstrum vocoder etc.

5. Which of the following pronunciations lead to voiced sound?
a) ‘f’
b) ‘s’
c) ‘sh’
d) ‘m’

View Answer

Answer: d [Reason:] Voiced sounds are ‘m’, ‘n’ and ‘v’ pronounciations. They are a result of quasiperiodic vibrations of the vocal chord.

6. Speech signal can be categorised in _____ and ______
a) Voiced, unvoiced
b) Active, passive
c) Direct, indirect
d) Balanced, unbalanced

View Answer

Answer: a [Reason:] Speech signal is of two types, voiced and unvoiced. Voiced sound is a result of quasiperiodic vibrations of the vocal chord. Unvoiced signals are fricatives produced by turbulent air flow through a constriction.

7. Channel vocoders are the time domain vocoders. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Channel vocoders are frequency domain vocoders. They determine the envelope of the speech signal for a number of frequency bands and then sample, encode and multiplex these samples with the encoded outputs of the other filters.

8. ________ is often called the formant of the speech signal.
a) Pitch frequency
b) Voice pitch
c) Pole frequency
d) Central frequency

View Answer

Answer: c [Reason:] The pole frequencies correspond to the resonant frequencies of the vocal tract. They are often called the formants of the speech signal. For adult speakers, the formants are centered around 500 Hz, 1500 Hz, 2500 Hz and 3500 Hz.

9. Formant vocoders use large number of control signals.
a) True
b) False

View Answer

Answer: b [Reason:] Formant vocoders use fewer control signals. Therefore, formant vocoders can operate at lower bit rates than the channel vocoder. Instead of transmitting the power spectrum envelope, formant vocoders attempt to transmit the position of peaks of spectral envelope.

10. Cepstrum vocoder uses _____
a) Wavelet transform
b) Inverse wavelet transform
c) Cosine transform
d) Inverse Fourier transform

View Answer

Answer: d [Reason:] Cepstrum vocoders use inverse Fourier transform. It separates the excitation and vocal tract spectrum by Fourier transforming spectrum to produce the cepstrum of the signal.

Communications MCQ Set 2

1. US cellular standard CDPD stands for _________
a) Cellular Digital Packet Data
b) Cellular Digital Packet Data
c) Cellular Digital Pocket Data
d) Cellular Discrete Pocket Data

View Answer

Answer: a [Reason:] US cellular standard CDPD stands for Cellular Digital Packet Data. In 1993, US cellular industry developed CDPD to coexist with the conventional voice only cellular system.

2. CDPD is data service for third generation US cellular systems.
a) True
b) False

View Answer

Answer: b [Reason:] CDPD is a data service for first and second generation US cellular systems and uses a full 30 kHz AMPS channel on a shared basis. CDPD provides mobile packet data connectivity to existing data networks.

3. Which of the following is true for CDPD?
a) Expensive to install
b) Uses different infrastructure
c) Complex
d) Inexpensive to install

View Answer

Answer: d [Reason:] CDPD directly overlays with existing cellular infrastructure and uses existing base station equipment, making it simple and inexpensive to install. CDPD does not use the MSC, but rather has its own traffic routing capabilities.

4. CDPD channel is ______
a) Simplex
b) Complex
c) Duplex
d) Expensive

View Answer

Answer: c [Reason:] Each CDPD channel is duplex in nature. The forward channel serves as a beacon and transmits data from the PSTN side of the network, while the reverse channel links all mobile users to the CDPD network and serves as the access channel for each subscriber.

5. CDPD transmissions are carried out using ______ blocks.
a) Fixed length
b) Variable length
c) Long
d) Short

View Answer

Answer: a [Reason:] CDPD transmissions are carried out using fixed length blocks. User data is protected using a Reed-Solomon (63, 47) block code with 6 bit symbols.

6. MDLP is ______
a) Layer protocol used in CDPD
b) Layer protocol used in GSM
c) Layer protocol used in ARDIS
d) Layer protocol used in CDMA

View Answer

Answer: a [Reason:] MDLP (Mobile data link protocol) is a lower layer protocol of CDPD. It is used to convey information between data link layer entities (layer 2 devices) across the CDPD air interface.

7. The layer protocol, RRMP stands for _______
a) Radio Resource Management Protocol
b) Radio Resource Mobile Protocol
c) Radio Rate Management Protocol
d) Radio Rate Mobile Protocol

View Answer

Answer: a [Reason:] The radio resource management protocol (RRMP) is a higher, layer 3 protocol used to manage the radio channel resources of the CDPD system and enables an M-ES to find and utilize a duplex radio channel without interfering with standard voice services.

8. ARDIS is a public network service.
a) True
b) False

View Answer

Answer: b [Reason:] ARDIS (Advanced Radio Data Information Systems) is a private network service provided by Motorola and IBM. It is based on MDC 4800 and RD-LAP protocols developed at Motorola.

9. RMD is a _______ and ________ data service.
a) Private, two way
b) Public, one way
c) Public, two way
d) Private, one way

View Answer

Answer: c [Reason:] RAM Mobile Data (RMD) is a public, two way data service based upon the Mobitex protocol developed by Ericsson. RAM provides street level coverage for short and long messages for users moving in an urban environment.

10. The MSC provides subscriber access to the PSTN via the _______
a) Signalling transfer points
b) Service management system
c) Database service management system
d) Switching end points

View Answer

Answer: d [Reason:] The MSC provides subscriber access to the PSTN via the switching end points (SEPs). The SEP implements a stored program control switching system known as the service control point (SCP).

11. ________ controls the switching of messages between nodes in the CCS network.
a) Signalling transfer points
b) Service management system
c) Database service management system
d) Switching end points

View Answer

Answer: a [Reason:] The signalling transfer point (STP) controls the switching of messages between nodes in the CCS network. For higher reliability of transmission, SEPs are required to be connected to the SS7 network via at least two STPs.

Communications MCQ Set 3

1. In a wireless communication, base station is connected to central hub called _______
a) PSTN
b) MSC
c) CO
d) PBX

View Answer

Answer: b [Reason:] 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

View Answer

Answer: a [Reason:] 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. State whether True or False.
a) True
b) False

View Answer

Answer: [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: d [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: d [Reason:] 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. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] 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

View Answer

Answer: a [Reason:] 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

View Answer

Answer: a [Reason:] 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.

Communications MCQ Set 4

1. What is the full form of WLAN?
a) Wide Local Area Network
b) Wireless Local Area Network
c) Wireless Land Access Network
d) Wireless Local Area Node

View Answer

Answer: b [Reason:] WLAN stands for Wireless Local Area Network. Wireless networks is increasingly used as a replacement for wires within homes, buildings, and office settings through the deployment of wireless local area networks (WLANs).

2. WLANs use high power levels and generally require a license for spectrum use. (True or False)
a) True
b) False

View Answer

Answer: b [Reason:] WLANs use low power and generally do not require a license for spectrum. They provide ad hoc high data transmission rate connections deployed by individuals. In the late 1980s, FCC provided licence free bands for low power spread spectrum devices in ISM band, which is used by WLAN.

3. What is the name of 300 MHz of unlicensed spectrum allocated by FCC in ISM band?
a) UNII
b) Unlicensed PCS
c) Millimetre wave
d) Bluetooth

View Answer

Answer: a [Reason:] FCC allocated 300 MHz of unlicensed spectrum in the ISM bands. This allocation is called the Unlicensed National Information Infrastructure (UNII) band. It was allocated for the express purpose of supporting low power license free spread spectrum data communication.

4. Which of the following specifies a set of media access control (MAC) and physical layer specifications for implementing WLANs?
a) IEEE 802.16
b) IEEE 802.3
c) IEEE 802.11
d) IEEE 802.15

View Answer

Answer: c [Reason:] IEEE 802.11 is a set of media access control and physical layer specification for implementing WLAN computer communication. It was founded in 1987 to begin standardization of spread spectrum WLANs for use in the ISM bands.

5. Which of the following is not a standard of WLAN?
a) HIPER-LAN
b) HIPERLAN/2
c) IEEE 802.11b
d) AMPS

View Answer

Answer: d [Reason:] AMPS is a standard of first generation network. HIPERLAN is a WLAN standard developed in Europe in mid 1990s. HIPERLAN/2 is also developed in Europe that provides upto 54 Mbps of user data.

6. Which of the following is the 802.11 High Rate Standard?
a) IEEE 802.15
b) IEEE 802.15.4
c) IEEE 802.11g
d) IEEE 802.11b

View Answer

Answer: d [Reason:] IEEE 802.11b was a high rate standard approved in 1999. It provided new data rate capabilities of 11 Mbps, 5.5 Mbps in addition to the original 2 Mbps and 1 Mbps user rates of IEEE 802.11.

7. Which of the following spread spectrum techniques were used in the original IEEE 802.11 standard?
a) FHSS and DSSS
b) THSS and FHSS
c) THSS and DSSS
d) Hybrid technique

View Answer

Answer: a [Reason:] Original IEEE 802.11 used both the approaches of FHSS (Frequency Hopping Spread Spectrum) and DSSS (Direct Sequence Spread Spectrum). But from late 2001s, only DSSS modems are used within IEEE 802.11.

8. Which of the following WLAN standard has been named Wi-Fi?
a) IEEE 802.6
b) IEEE 802.15.4
c) DSSS IEEE 802.11b
d) IEEE 802.11g

View Answer

Answer: c [Reason:] The DSSS IEEE 802.11b standard has been named Wi-Fi by the Wireless Ethernet Compatibility Alliance. It is a group that promotes adoption of 802.11 DSSS WLAN.

9. Which of the following is developing CCK-OFDM?
a) IEEE 802.11a
b) IEEE 802.11b
c) IEEE 802.15.4
d) IEEE 802.11g

View Answer

Answer: d [Reason:] IEEE 802.11g is developing CCK-OFDM (Complimentary Code Keying Orthogonal Frequency Division Multiplexing) standards. It will support roaming capabilities and dual band use for public WLAN networks. It also has backward compatibility with 802.11b technologies.

10. What is the data rate of HomeRF 2.0?
a) 10 Mbps
b) 54 Mbps
c) 200 Mbps
d) 1 Mbps

View Answer

Answer: a [Reason:] HomeRF 2.0 has data rate of the order of 10 Mbps. The FHSS proponents of IEEE 802.11 have formed the HomeRF standard that supports the frequency hopping equipment. In 2001, HomeRF developed a 10 Mbps FHSS standard called HomeRF 2.0.

11. HIPER-LAN stands for ______
a) High Precision Radio Local Area Network
b) High Performance Radio Local Area Network
c) High Precision Radio Land Area Network
d) Huge Performance Radio Link Access Node

View Answer

Answer: b [Reason:] HIPER-LAN stands for High Performance Radio Local Area Network. It was developed in Europe in mid 1990s. It was intended to provide individual wireless LANs for computer communication.

12. What is the range of asynchronous user data rates provided by HIPER-LAN?
a) 1-100 Mbps
b) 50-100 Mbps
c) 1-20 Mbps
d) 500 Mbps to 1 Gbps

View Answer

Answer: c [Reason:] HIPER-LAN provides asynchronous user data rates of between 1 to 20 Mbps, as well as time bounded messaging of rates of 64 kbps to 2.048 Mbps. It uses 5.2 GHz and 17.1 GHz frequency bands.

13. What is the name of the European WLAN standard that provides user data rate upto 54 Mbps?’
a) UNII
b) WISP
c) MMAC
d) HIPERLAN/2

View Answer

Answer: d [Reason:] HIPERLAN/2 has emerged as the next generation European WLAN standard. It provides upto 54 Mbps of user data to a variety of networks. The networks includes the ATM backbone, IP based networks and the UMTS network.

14. What is WISP?
a) Wideband Internet Service Protocol
b) Wireless Internet Service Provider
c) Wireless Instantaneous Source Provider
d) Wideband Internet Source Protocol

View Answer

Answer: b [Reason:] WISP is wireless Internet Service Provider used to explore public LANs (publan). It builds a nationwide infrastructure of WLAN access points in selected hotels, restaurants or airports. It then charges a monthly subscription fee to users who wish to have always on Internet access in those selected locations.

15. The price of WLAN hardware is more than 3G telephones and fixed wireless equipment.(True or False)
a) True
b) False

View Answer

Answer: b [Reason:] As, WLAN could be used to provide access for the last 100 meters into homes and businesses. Therefore, the price of WLAN hardware is far below 3G telephones and fixed wireless equipment.

Communications MCQ Set 5

1. _______ is responsible for tunneling multicast packets to the MS’s currently subscribed FA.
a) Multicast home agent
b) Mobile multicast
c) Mobile station
d) Base station

View Answer

Answer: a [Reason:] Multicast home agent (MHA) is responsible for tunneling multicast packets to the MS’s currently subscribed FA. MHA serves MSs that are roaming around the foreign networks and are within its service range.

2. Every MS can have only one MHA. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] Every MS can have only one MHA, which dynamically changes based on the location of the MS, whereas a HA of a MS never changes. The protocol requires that each MHA must be a multicast group member.

3. _______ provides a fast and efficient handoff for MSs in foreign networks.
a) MHA
b) MMP
c) CBT
d) MS

View Answer

Answer: b [Reason:] MMP provides a fast and efficient handoff for MSs in foreign networks. It also enables location-independent addressing.

4. MMP combines the concepts of _______ and ________
a) Mobile IPs, GSM
b) Core based trees, GSM
c) Mobile IPs, core based trees
d) Core based trees, LTE

View Answer

Answer: c [Reason:] MMP combines the concepts of Mobile IP and core-based trees (CBT). Here the former controls communication up to the foreign network, and the latter manages movement of the MSs inside them.

5. ________ designed for an Internet work environment with small wireless cells.
a) MMP
b) RMDP
c) RM2
d) Mobicast

View Answer

Answer: d [Reason:] Mobicast is designed for an Internet work environment with small wireless cells. It assumes that a set of cells are grouped together and are served by a domain foreign agent (DFA).

6. ________ serve as multicast forwarding agents and are meant to isolate the mobility of the mobile host from the main multicast delivery tree.
a) DFA
b) MHA
c) FA
d) MMP

View Answer

Answer: a [Reason:] DFAs serve as multicast forwarding agents and are meant to isolate the mobility of the mobile host from the main multicast delivery tree. This hierarchical mobility management approach tries to isolate the mobility of the FAs from the main multicast delivery tree.

7. Mobicast is based on a method proposed by the IETF to support multicast over Mobile-IP. State whether True or False.
a) True
b) False

View Answer

Answer: a [Reason:] Mobicast is based on a method proposed by the IETF to support multicast over Mobile-IP. To handle the case when a MS is both the source and recipient of a multicast session, one needs to minimize the possibility of rebuilding the complete multicast tree at each foreign domain the MS visits.

8. _______ is meant to be implemented for use on the MBONE.
a) MMP
b) RMDP
c) RM2
d) Mobicast

View Answer

Answer: b [Reason:] The reliable multicast data distribution protocol (RMDP) is meant to be implemented for use on the MBONE. It relies on the use of FEC and ARQ information to provide reliable multicast service.

9. __________ is a is a reliable multicast protocol and is used for both wired and wireless environments.
a) MMP
b) RMDP
c) RM2
d) Mobicast

View Answer

Answer: c [Reason:] Reliable mobile multicast (RM2) is a reliable multicast protocol and is used for both wired and wireless environments. RM2 guarantees sequential packet delivery to all its multicast members without any packet loss.

10. ______ relies on IGMP.
a) MMP
b) RMDP
c) RM2
d) Mobicast

View Answer

Answer: c [Reason:] RM2 relies on the Internet group management protocol (IGMP) to manage multicast group membership. RM2 is a hierarchical protocol that divides a multicast tree into subtrees, whereby subcasting within these smaller regions is applied using a tree of retransmission servers.