B.Tech
(U.P.T.U.)
EIGHT
SEMESTER EXAMINATION, 2003-2004
Wireless
communications
Q.1
Attempt any four parts of the following: (5*4=20
Marks)
Q.1(a)
Define the far-field (or fraunhofer region)of a transmitting antenna.
Find out the received power n dBm at a free space distance of 1 km if
the power transmitted from a unity gain antenna is 50 watts.
Q.1(b)
Name some of the commonly used outdoor propagation models for mobile
commutation systems. Discuss any one of these in brief.
Q.1(c)
Explain, briefly the physical factors influencing small-scale fading
in radio channels.
Q.1(d)What
are various time dispersion multipath channel parameters used for
designing of wireless systems? Define them and give their
mathematical expression.
Q.1(e)
A flat Rayleigh signal at 6 GHz is received by a mobile travelling at
60 km/hr. Determine duration of a fade below the rms level.
Q.1(f)
How much bandwidth is required for an analog frequency modulated
signal that has an audio bandwidth of 5KHz and a index of three? How
much output SNR improvement would be obtained, if the modulation
index is increased to five? what is the trade off bandwidth for this
improvement?
Q.2
Attempt any four parts of the following: (5*4=20 Marks)
Q.2(a)Discuss
a method of locating co-channel cells in a cellular system.
Q.2(b)With
the help of received signal level plot, explain the difference
between an improper and a proper hand off situation.
Q.2(c)
Give a point-by-point brief note an channel planning for wireless
systems.
Q.2(d)
What are the various techniques possible to improve coverage and
capacity in cellular systems? discuss cell splitting in brief.
Q.2(e)How
does Gaussian MSK differ from MSK? discuss GMSK in brief.
Q.2(f)What
makes code-Excited lpc(CE-LPC) a difficult option as speech encoder
out of other LPC encoders? Discuss in brief.
Q.3
Attempt any two parts of the following: (10*2=20
Marks)
Q.3(a)
Define bandwidth efficiency and relate it with error correction
capability in bandwidth limited application. Discuss any block code
encoder and decoder used for error correction.
Q.3(b)
What is the fundamental difference in concepts for calculating the
capacity CDMA cellular system over FDMA cellular system.
Q.3(c)
Giving in brief description of system architecture and interfaces.
discuss GSM system for mobile communication.
Q.4
Attempt any two parts of the following: (10*2=20 Marks)
Q.4(a)
Describe a common channel signaling (CCS)network architecture based
on SS7.Discuss network services part of SS7 and draw a layered SS7
protocol architecture.
Q.4(b)
Give a brief account of developments so far achieved in wireless
multimedia services.
Q.4(c)
What restricts a wireless in local (WLL) service to be regarded a
mobile cellular service? compare both to highlight technological
difference or similarities.
Q.5
Attempt any two parts of the following: (10*2=20 Marks)
Q.5(a)
Mobile satellite communication.
Q.5(b)
Third generation cellular systems.
Q.5(c)
Universal mobile telecommunication systems.
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