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1. Dear students get fully solved assignments
Send your semester & Specialization name to our mail id :
“ help.mbaassignments@gmail.com ”
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Assignment
PROGRAM BCA(SPRING 2015)
SEMESTER 3
SUBJECT CODE & NAME BCA 3040– DATA COMMUNICATION
CREDIT 4
BK ID B1644
MAX.MARKS 60
1. What is modulation? Explain why modulation is required?
Answer : Modulation is the addition of information (or the signal) to an electronic or optical signal
carrier.Modulationcan be applied to direct current (mainly by turning it on and off), to alternating
current, and to optical signals.
Amplitude modulation (AM
Frequency modulation (FM),
Phase modulation (PM), in which the natural flow of the alternating current waveform is delayed
temporarily
Modem Modulation and Demodulation
A computer with an online or Internet connection that connects over a regular analog phone line
includes a modem.
Need for modulation
The aim of digital modulationistotransferadigital bitstream over an analog bandpass channel, for
example over the public switched telephone network
2. Write short note on:
1. Ground Wave Propagation
Answer : Ground Wave propagation is a method of radio frequency propagation that uses the area
between the surface of the earth and the ionosphere for transmission.

2. 2. Sky Wave Propagation
Answer : Sky wave propagation: The sky waves have frequency range between 2MHz to 30MHz.
Some important terms which are used more frequently in sky wave propagation are given below:
1. Maximum Usable frequency
2. Critical frequency
3. Skip distance
4. Fading
3. Briefly explain Nyquist theorem with mathematical representation.
Answer: The Nyquist–Shannon sampling theorem, which has been named after Harry Nyquist and
Claude Shannon, is a fundamental result in the field of information theory,

3. 4. What is Time-division multiplexing (TDM)? Explain.
Answer:TDM is a commonform of sendingmultiple signalsorstreamsof informationona carrier at
the same time in the form of a single
Benefits and shortcomings of TDM
The relative simplicity and low cost of TDM hardware devices makes it possible to build cost-
effective networks of widely varying node count, geographic extent, capacity, and speed.
Examples of TDM based services
Public telephone networks
T1 - The T-carrier system is entirely digital, using pulse code modulation and time division
multiplexing.
5. Write short note on:
1. Least-Cost Algorithms
Answer:In practice,the majorityof Internetroutingmethodsare basedon least-cost algorithms. In
such algorithms, a link cost is proportional to the links's current traffic load.
2. Dijkstra’s Algorithm
Answer:Dijkstra's algorithm,conceivedby computerscientist EdsgerDijkstrain1956 and published
in 1959,[1][2]
is a graph search algorithm that solves the single-source shortest path problem for
a graph with non-negative edge path costs, producing ashortest path tree
6. What are the requirements of Wirelesses LAN? Explain briefly
Answer:A wirelessLAN mustmeetthe same sortof requirementstypical of anyLAN, including high
capacity, ability to cover short distances, full connectivity among attached stations, and broadcast
capability.Inaddition,anumberof requirementsare specificto the wireless LAN environment. The
following are among the most important requirements for wireless LANs:

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