Instruction
- Total number of questions : 8
- Time allotted : 12:00 Minutes:Seconds.
- Each question carry 1 mark, no negative marks.
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Mobile Communication [ Question No: 1 To 8 ] :
Which of the following technology distributes the coverage of the cell and extends the cell boundary to hard-to-reach places ?
The guard interval is provided in Orthogonal Frequency-Division Multiplexing (OFDM).
GSM is an example of :
The commonly used mode for 3G Networks is :
Which of the following are limitations of mobile computing?
Limitations:
i) Device mobility
ii) Power consumption
iii) Human interface with device
iv) Range and Bandwidth
v) Transmission interferences
vi) Wireless connectivity
In Managed Ad-hoc Network (MANET), under which attack, malicious node injects fault routing information to the network, in order to locate packets into a loop?
Match the column Mobility with the column Descriptions.
| Mobility | Descriptions |
|---|---|
| a) Macro-mobility | i) This is mobility within a MANET, caused by device mobility constantly changing the network topology. |
| b) Micro-mobility | ii) This is mobility through a global network. |
| c) Ad hoc mobility | iii) This is mobility of a device in one single administrative domain of the global network. |
Mobile Agents are also called ______ agents. They are of two types: Mobile Agents with pre-defined path and Mobile Agents with undefined path.
Total number of questions : 8
Number of answered questions : 0
Number of unanswered questions : 8
Mobile Communication [ Question No: 1 To 8 ] :
Which of the following technology distributes the coverage of the cell and extends the cell boundary to hard-to-reach places ?
Your Answer : (Not Answered)
Correct Answer : C
The micro cell zone concept distributes the coverage of a cell and extends its boundary to hard-to-reach places.
In this technique (described in Rappaport's Wireless Communications) one base station serves a cell divided into several zones, each covered by a small, low-power zone transmitter connected to the base station. As a mobile moves between zones within the cell it stays on the same channel and no handoff is needed. The zone sites can be placed in tunnels, valleys or along roads, so coverage reaches spots a single site would miss, and interference falls.
Sectoring divides a cell with directional antennas to reduce interference, and cell splitting creates smaller cells to increase capacity. Scattering is a propagation effect, not a cell design technique.
The guard interval is provided in Orthogonal Frequency-Division Multiplexing (OFDM).
Your Answer : (Not Answered)
Correct Answer : D
The guard interval serves both (A) and (B).
In OFDM, a guard interval (usually a cyclic prefix, a copy of the end of each symbol placed at its start) is inserted between symbols. Delayed copies of the previous symbol arriving by multipath fall into this interval, so they do not overlap the useful part of the next symbol, which eliminates inter-symbol interference (ISI). Because each symbol is then effectively isolated, OFDM also does without the pulse-shaping filter that single-carrier systems need for ISI control.
The guard interval does not raise the symbol rate; it lowers it slightly, since part of each symbol period carries no new data.
GSM is an example of :
Your Answer : (Not Answered)
Correct Answer : A
GSM is an example of TDMA cellular systems.
GSM divides each 200 kHz carrier into eight time slots, and each user transmits in its own slot, which is time division multiple access. It also uses FDMA to separate carriers, but its defining multiple access scheme is TDMA.
CDMA (code division) is used by IS-95 and cdma2000 networks, and FDMA alone was the scheme of first-generation analog systems such as AMPS.
The commonly used mode for 3G Networks is :
Your Answer : (Not Answered)
Correct Answer : D
The commonly used mode for 3G networks is FDD, frequency division duplex.
Most 3G systems, including UMTS with W-CDMA and CDMA2000, use paired frequency bands, one for the uplink and one for the downlink, which is frequency division duplex. TDD versions such as TD-SCDMA were deployed far less widely.
TDMA is the access method of 2G GSM and is not the 3G mode, and CSMA is the contention method of local area networks such as Ethernet and Wi-Fi.
Which of the following are limitations of mobile computing?
Limitations:
i) Device mobility
ii) Power consumption
iii) Human interface with device
iv) Range and Bandwidth
v) Transmission interferences
vi) Wireless connectivity
Your Answer : (Not Answered)
Correct Answer : A
The limitations of mobile computing are power consumption, the human interface with the device (small screens and keypads), range and bandwidth, and transmission interferences, which are ii, iii, iv and v. Device mobility and wireless connectivity are what makes mobile computing possible, so they are features and not limitations. The other options include one of those two or leave out limitations. Small screens, short battery life, limited bandwidth and interference are the reasons these items count as limitations of mobile devices.
In Managed Ad-hoc Network (MANET), under which attack, malicious node injects fault routing information to the network, in order to locate packets into a loop?
Your Answer : (Not Answered)
Correct Answer : A
This is the Byzantine attack. In it a compromised node, or a group of them, works against the network by injecting faulty routing information, which can create routing loops and send packets along non-optimal paths. A wormhole attack tunnels packets between two colluding nodes, snooping is eavesdropping on traffic, and a DNS attack goes after name resolution, so they do not describe the injection of false routing information to form a loop.
Match the column Mobility with the column Descriptions.
| Mobility | Descriptions |
|---|---|
| a) Macro-mobility | i) This is mobility within a MANET, caused by device mobility constantly changing the network topology. |
| b) Micro-mobility | ii) This is mobility through a global network. |
| c) Ad hoc mobility | iii) This is mobility of a device in one single administrative domain of the global network. |
Your Answer : (Not Answered)
Correct Answer : A
The correct match is a-ii, b-iii, c-i. Macro-mobility is mobility through a global network (ii). Micro-mobility is the mobility of a device within one single administrative domain of the global network (iii). Ad hoc mobility is mobility within a MANET, caused by device mobility constantly changing the network topology (i). The other options swap at least one of these pairs. Mobile IP is the usual example of macro-mobility, in which a device keeps its address while moving between networks.
Mobile Agents are also called ______ agents. They are of two types: Mobile Agents with pre-defined path and Mobile Agents with undefined path.
Your Answer : (Not Answered)
Correct Answer : A
Mobile agents are also called transportable agents, according to the key. A mobile agent is a program that can move from one host to another, and the two types in the question depend on whether the path it follows is fixed in advance or left undefined. 'Migrator', 'connector' and 'linker' are not the standard alternative names for a mobile agent. A mobile agent carries its code and state from one host to another, which is why the word transportable describes it.
Marks
Total number of questions : 8
Number of answered questions : 0
Number of unanswered questions : 8