Cellular and mobile communication Jntu Model Paper{Www.Studentyogi.Com}

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Code No: RR420401
Set No. 1
IV B.Tech II Semester Regular Examinations, Apr/May 2007
CELLULAR AND MOBILE COMMUNICATION
( Common to Electronics & Communication Engineering, Computer Science
& Engineering, Information Technology, Computer Science & Systems
Engineering and Electronics & Computer Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks

1. (a) Di erentiate the generations in the cordless phones and cellular phones?
(b) Explain about the dynamic channel assignment? [10+6]

2. (a) What are the components in a cellular system explain brie y?
(b) Explain about the term co-channel reduction factor. [8+8]

3. (a) A base station receiver capable of providing 80db of isolation between channels
is receiving a signal from a mobile unit 2 Km away. What is the minimum
distance that a second mobile unit can transmit the signal from the near end
mobile unit.
(b) Write a brief note on designing directional antenna system considering the
e ect of interference. [8+8]

4. (a) From the signal coverage point of you explain ground incident angle, elevation
angle, ground re ection and re ection point?
(b) If h1 = 50mt, 2 = 3mt, d = 5Km, H = 100m use approximate method nd
incident angle, elevation angle, ground re ection and re ection point? [8+8]

5. (a) Derive the relation between the received power and electrical eld of the an-
tenna?
(b) Assume a receiver is located 10km from a 50W transmitter. The carrier fre-
quency is 900MHz , assume free space propagation Gt = 1 and Gr = 2W
i. Find the power at the receiver
ii. The magnitude of the electric eld at the receiving antenna
iii. The rms voltage applied to the receiver input assuming that the receiving
antenna has purely real importance of 50 ohms and is matched to the
receiver. [6+10]

6. (a) Discuss the concept of frequency management concern to the numbering the
channels and grouping into the subsets?
(b) Give the structure of the channels in 800MHz system with frequency ranges?
[8+8]

7. (a) Explain clearly how to calculate and for single cell?


Code No: RR420401
Set No. 1
(b) Why hand o is necessary for cellular systems Determine the two types of
hando s based on signal strength and C/I ratio? [8+8]

8. (a) As a mobile unit in a communication with base station moves, what factors
determine the need for power control and the amount of power adjustment?
(b) Explain the di erence between the open loop and closed loop power control.
[8+8]


Code No: RR420401
Set No. 2

1. (a) Draw the schematic and the present the working of a cellular system?
(b) Brie y explain the evaluation of the analog and digital cellular mobile system?
[8+8]

2. (a) Derive the maximum number calls per hour per cell and the maximum number
frequency channels per cell . How are they related?
(b) Find the desire co channel interference phenomena in a reuse cellular system
that employs omni directional antenna system? [8+8]

3. (a) Distinguish between co channel interference and non co channel interference?
(b) Discuss the various techniques to measure the co channel interference? [8+8]

4. (a) Discuss about the multi path propagation present the associated losses and
place the problem?
(b) Discuss about the point to point and area to area prediction mo del for cell
coverage? [10+6]

5. (a) Derive the relation between the received power and electrical eld of the an-
tenna?
(b) Assume a receiver is located 10km from a 50W transmitter. The carrier fre-
quency is 900MHz , assume free space propagation Gt = 1 and Gr = 2W
i. Find the power at the receiver
ii. The magnitude of the electric eld at the receiving antenna
iii. The rms voltage applied to the receiver input assuming that the receiving
antenna has purely real importance of 50 ohms and is matched to the
receiver. [6+10]

6. The U.S AMPS system is allocated 50MHz of spectrum in the 800 Mhz range and
provides 832 channels. 42 of those channels are control channels. The forward
channel frequency is exactly 45MHz greater then the reverse channel frequency.

(a) If the AMPS system is simplex, half duplex or full duplex? What is the band
width for each channel and how is it distributed between the base station and
subscriber?


Code No: RR420401
Set No. 2
(b) Assume a base station transmits control information on channel 352, operating
at 880.560MHz What is the transmission frequency of the subscriber unit on
transmitting on channel 352?
(c) The A- side and B - Side cellular carriers evenly split the AMPS channels.
Find the number of voice channels and the number of control channels for
each carrier?
(d) let suppose you are chief engineer of a cellular system using seven cell reuse pur-
pose a channel assignment strategy for a uniform distribution of user through
out your cellular system speci cally , assume that each cell has three control
channels (1200 sector is employed)and specify the number of voice channels
you would assign to each control in your system?
(e) For an ideal hexagonal cellular layout which has an identical cell coverage,
what is the distance between the centers of two nearest co channel cells for
seven cell reuse? For four cell reuse? [16]

7. Explain the necessity of power di erence hando ? Also explain the di erent con-
ditions based on power di erence hando ? [16]

8. Present the concept of the narrow beam sector. How do es it increase the tra c
capacity? Consider K = 7. [16]


Code No: RR420401
Set No. 3

1. (a) Present the model of the mobile transmission medium and the fading charac-
teristics?
(b) Explain in detail coherence bandwidth and delay spread? [8+8]

2. (a) Derive the maximum number calls per hour per cell and the maximum number
frequency channels per cell . How are they related?
(b) Find the desire co channel interference phenomena in a reuse cellular system
that employs omni directional antenna system? [8+8]

3. (a) Explain how co channel interference is measured in real time mobile radio
transceivers?
(b) Prove that K = 7 cell pattern do es not provide a su cient frequency reuse
distance even when an ideal conditions of at terrain is assumed? [6+10]

4. (a) Brie y explain the multiple knife edge di raction?
(b) Explain about the scattering phenomena in mobile system? [8+8]

5. (a) Discuss the characteristics of cell site antennas?
(b) If the antenna heights are varying what are the e ects you are getting at the
time of operation of mobile system? [8+8]

6. Explain the following

(a) Channel sharing
(b) Channel borrowing

(c) Underlay and overlay cells
(d) Setup channel
(e) Paging channel
(f ) Voice channel. [16]

7. What is hando and explain di erent type of hando s? [16]

8. (a) As a mobile unit in a communication with base station moves, what factors
determine the need for power control and the amount of power adjustment?


Code No: RR420401
Set No. 3
[8+8]


Code No: RR420401
Set No. 4

1. (a) What do you mean by Mean Opinion Score and explain in detail?
(b) Explain the history of 800MHz spectrum allocation to cellular systems?[8+8]

2. (a) A cellular system uses FDMA with a spectrum allocation of 12.5MHz in each
direction a guard band at the edge of the allocated spectrum of 10KHz at
channel bandwidth of 30KHz What is the number of the available channels?
(b) If 8 Speech channels are provided in a single radio channel and if no guard band
is assumed what is the number of simultaneous users that can accommodate
in GSM receiver? [8+8]

3. (a) Distinguish between frequency and time selective fading with neat diagrams.
(b) Discuss angular and frequency diversity schemes. [8+8]

4. (a) Consider a transmitter which radiates a sinusoidal carrier frequency of 1859
MHz. For a vehicle moving 60 miles/hr compute the received carrier frequency
if the mobile is moving.
i. Directly towards the transmitter
ii. Directly away from the transmitter
iii. In a direction perpendicular to the direction of arrival of the transmitted
signal.
(b) Derive the expression for the power received in ground re ected model. [8+8]

5. (a) Explain the relation between gain and antenna pattern for broad side and end
re array?
(b) Explain the relation between gain and beam width for broad side and end re
array?
(c) For a gain of 9dB with respect to a dipole antenna or 11dB with respect to a
short dipole antenna nd 3dB beam width? [6+6+4]

6. (a) Discuss the concept of frequency management concern to the numbering the
channels and grouping into the subsets?
(b) Give the structure of the channels in 800MHz system with frequency ranges?
[8+8]


Code No: RR420401
Set No. 4
7. (a) List and brie y de ne di erent performance metrics that may be used to make
the hando decision?
(b) If the number channels at the cell site N=45 the call holding time is 1.76minutes
The number of originated calls per hour expressed as is 2270. The number
of hando calls attempted per hour is expressed as 2 is 80 Find the probabil-
ity of the queuing hando . calls but not the originated calls . Also nd the
probability of the queuing the originated calls but not the hando calls?

[10+6]

8. Present the concept of the narrow beam sector. How do es it increase the tra c
capacity? Consider K = 7. [16]

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Cellular and mobile communication Jntu Model Paper{Www.Studentyogi.Com}