Question Papers.pdfb) Distinguish between permenant splitting and dynamic splitting. [5+5] OR 3.a) Mention the two frequency reuse schemes and explain N-Cell reuse pattern in detail

Code No: 117BG

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

B. Tech IV Year I Semester Examinations, March - 2017

CELLULAR AND MOBILE COMMUNICATIONS

(Electronics and Communication Engineering)

Time: 3 Hours Max. Marks: 75 Note: This question paper contains two parts A and B.

Part A is compulsory which carries 25 marks. Answer all questions in Part A.

Part B consists of 5 Units. Answer any one full question from each unit. Each

question carries 10 marks and may have a, b, c as sub questions.

Part- A (25 Marks)

1.a) Mention the limitations of conventional mobile telephone systems. [2]

b) Discuss the dependence of frequency reuse distance on cell reuse pattern. [3]

c) Explain polarization diversity. [2]

d) Mention the effect on coverage and interference of mobile link by decrease in transmitted

power level. [3]

e) List the antennas used for space diversity. [2]

f) State the factors on which the minimum separation of cell site antennas depends. [3]

g) List any three techniques for increasing frequency spectrum utilization. [2]

h) Define spectrum utilization factor. [3]

i) Explain the need for hand off. [2]

j) Define intersystem hand off. [3]

Part-B (50 Marks)

2. Explain the steps involved in planning a cellular system. Illustrate how the performance

criteria is evaluated. [10]

OR 3. Explain briefly different ways of improving coverage and capacity in cellular systems.

[10]

4. Determine the real time co-channel interference measurement of mobile radio

transreceivers. [10] OR

5. Explain the near field and far field interference and how to avoid it. [10]

6. Let a distance between two fixed stations be 40 Km. The effective antenna height at one

end h1 is 200m above sea level. Find h2 at the other end so that the received power always

meets the condition Pr<Po (the received power is less than received power in free space)

at 850 MHz transmission. Find the range of h2 which would keep Pr>Po and find the

maximum received power Pr for Pr=4Po. [10]

OR

7. Derive the path loss prediction model in non obstructive condition. [10]

R13

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8.a) Describe in detail the adjacent channel assignment using omni-directional and directional

antennas.

b) Explain how channel sharing and borrowing is performed.

c) Compare omni and sectorized cells for seven cell system in fixed channel assignment.

[4+2+4] OR

9. Illustrate the frequency management chart and spectrum allocation for 666 channels and

discuss the functions of set up and voice channels. [10]

10. Explain about:

a) Dropped calls

b) Mobile assisted hand off

c) Soft hand off. [10]

OR

11. Explain in detail the need for hand off and determine the probability of requirement of

hand off. [10]

---ooOoo---


Code No: 117BG

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

B. Tech IV Year I Semester Examinations, November/December - 2017 CELLULAR AND MOBILE COMMUNICATIONS

(Electronics and Communication Engineering)

Time: 3 Hours Max. Marks: 75

Note: This question paper contains two parts A and B.

Part A is compulsory which carries 25 marks. Answer all questions in Part A.

Part B consists of 5 Units. Answer any one full question from each unit. Each

question carries 10 marks and may have a, b, c as sub questions.

PART - A

(25 Marks)

1.a) What are the limitations of conventional mobile telephone system. [2]

b) Explain real time Co- Channel interference. [3]

c) Define the General formula for noise limited system. [2]

d) Draw the antenna equivalent circuit. [3]

e) What is the commonly used formula for interference limited system? [2]

f) What are the advantages of sectorized cells? [3]

g) Define frequency reuse distance [2]

h) Explain the phase difference between direct and reflected paths. [3]

i) Explain about paging channels. [2]

j) Define Handoff. [3]

PART - B

(50 Marks)

2.a) Describe the digital cellular land mobile systems and the limitations of AMPS standard.

b) Distinguish between permenant splitting and dynamic splitting. [5+5]

OR

3.a) Mention the two frequency reuse schemes and explain N-Cell reuse pattern in detail for

four and seven cell reuse with illustrative diagrams.

b) Discuss the performance criteria of the basic cellular system? [5+5]

4.a) Explain about the co-channel interference reduction factor and derive the general formula

for C/I.

b) Briefly explain the multiple knife edge diffraction. [5+5]

OR

5.a) Compare and contrast Near end and Far end interferences.

b) Briefly discuss different diversity techniques. [5+5]

6.a) Explain the concept of diversity antenna spacing in cell site with a simple Diagram.

b) Compare the symmetrical and asymmetrical patterns. [5+5]

OR

R13


7.a) Explain about High gain antennas

b) Explain the role of directional antennas for interference reduction. [5+5]

8.a) What do you understand by non-fixed channel assignment? Describe the corresponding

algorithms.

b) Explain about the Underlay-Overlay Arrangement. [5+5]

OR 9.a) Describe the concept of frequency management concern to the numbering the Channels

and grouping into the subset.

b) Explain in detail access channels and operational techniques. [5+5]

10.a) Explain how the handoffs implemented based on signal strength.

b) How the dropped call rate is related to the capacity and voice quality. [5+5]

OR 11.a) What are the various methods of delaying the handoff? Explain briefly.

b) What is meant by handoff initiation? Explain the different methods of handoff initiation

with suitable diagrams. [5+5]

--ooOoo--


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Code No: N0422 R07

IV B.Tech. I Semester Supplementary Examinations, February/March 2012


(Common to Electronics & Communication Engineering and Electronics & Computer

Engineering)

Time: 3 Hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

*******

1. a) Explain the working of a cellular mobile system. [8] b) Discuss Analog cellular system. [8]

2. a) What is meant by Frequency reuse? Explain the available frequency reuse schemes. [8]

b) Explain the Two methods of cell splitting. [8]

3. a) Define C C I and explain how it is measured at the mobile unit. [8]

b) Discuss the effects of antenna parameters on the cell interferences. [8]

4. a) Discuss the standard deviations in obtaining mobile point to point (Lee Model) model.

[8]

b) If fc = 900MHz, ht = 40mt, hr = 5 mt and d = 10km. Estimate the path loss medium size

city. [8]

5. Explain the following [8+8]

a) Roof Mounted Antennas

b) Umbrella Pattern Antennas


a) Adjacement Channel assignment.

b) Sectorization

7. a) Explain the following Hand offs

i) Power difference Hand off

ii) Cell site hand off [8]

b) Explain Real time splitting with a neat figure. [8]

8. a) Distinguish between T D M A and C D M A. [8]

b) Write short notes on „G S M Channels‟ [8]

1 of 1

Set No. 1


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Code No: N0422 R07

IV B.Tech. I Semester Supplementary Examinations, February/March 2012



Engineering)




*******

1. a) Discuss the limitations of conventional Mobile telephone systems. [8] b) Describe the mobile radio transmission medium and discuss the fading

characteristics. [8]

2. a) Derive the desired carries to interference (C/I) ratio from a normal case in an Omini

directional antenna systems. [8]

b) What are the advantages of Cell splitting? Distinguish between permanent splitting

and Dynamic splitting with a neat figures. [8]

3. a) Explain how Co-channel interference is measured in Real time Mobile trans receiver.

[8]

b) Discuss the effects of reduced power, reduced antenna height and beam tilt on

coverage area and interference. [8]

4. a) Describe point to point transmission between two fixed stations over water or flat

open land. [10]

b) Discuss the merit of point to point model [6]


a) Mobile high gain antennas

b) Directional Antennas for interference reduction use.

6. a) Give the Comparison of Omini cells and sectorized cells [8]

b) Explain the channel sharing and Borrowing with neat figures. [8]

7. a) Explain the concept of delaying Hand off and Discuss the advantages of delayed

Hand off. [8]

b) Explain how 6 and µ are improved due to the natural two site diversity in the hand

off regain. [8]

8. a) Draw the GSM architecture and Explain. [8]

b) Mention the salient features of C D M A. [8]

1 of 1

Set No. 2


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Code No: N0422 R07 IV B.Tech. I Semester Supplementary Examinations, February/March 2012



Engineering)




*******

1. a) Explain the role of an Engineer in planning and operation of cellular networks. [8] b) Writer short notes on “Digital Cellular Systems”. [8]

2. a) Draw the general view of cellular telecommunication system and explain its

functioning of each unit. [8]

b) Explain the concept of frequency reuse channels. [8]

3. a) Show that C/I for directional antenna in K = 7 cell pattern in 3 sector case is 24.5 dB.

[8]

b) Distinguish between next channel interference and neighboring channel interference.

[8]

4. a) Derive the transfer function of the propagation channel in mobile – mobile land

communication. [8]

b) What is foliage loss? Discuss in detail. [8]


a) Omni directional antennas for coverage use.

b) Horizontally oriented space diversity antennas

6. a) Distinguish between frequency management and channel assignment. [8]

b) What do you understand by non fixed channel assignment? Describe the

corresponding algorithms. [8]

7. Write short notes on

a) “Qeuing of Hand offs” [8]

b) Explain clearly how to calculate „6‟ and „µ‟ for single cell. [8]

8. a) Draw the GSM architecture and discuss various interfaces used in GSM. [8]

b) Discuss the important features of TDMA and CDMA. [8]

1 of 1

Set No. 3


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Code No: N0422 R07 IV B.Tech. I Semester Supplementary Examinations, February/March 2012



Engineering)




*******

1. a) Discuss the performance criteria of cellular system. [8] b) Draw the basic cellular system and explain the functions of three parts. [8]

2. a) Explain the Co- channel interference reduction factor and derive the general

formula for C/I. [8]

b) Determine the frequency reuse distance for K = 4, 7, 12, 19. [8]

3. a) Explain the principle of operation of Diversity receiver. [8]

b) Explain the different types of Non Co-channel interference. [8]

4. a) Discuss the various parameter of a cell system that can be adjusted to increase

coverage. [10]

b) Discuss the land to mobile radio propagation over water. [6]

5. a) What do you understand by Engineering antenna pattern? Explain the corresponding

patterns. [8]

b) Explain the concept of vertically oriented space diversity antennas. [8]

6. Explain the following in brief

a) Paging channels

b) Channel sharing and borrowing

c) Under laid- overlaid cell arrangements [6+6+4]

7. a) Write short notes on “Mobile Assisted Handoff”. [8]

b) Prove that sectoring decreases trunking efficiency with an example. [8]


a) GSM Channels

b) CDMA

1 of 1

Set No. 4

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Code No: A107410403 Set No. 1 JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

IV B.Tech. I Sem., I Mid-Term Examinations, September – 2011


Objective Exam Name: Hall Ticket No.

Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 20.

I Choose the correct alternative:

1. The frequency reuse distance is determined from [ ]

A) D=R/√ (3K) B) D=√ (3K)/R C) D=R√ (3K) D) D=K√ (3R)

2. In Permanent Cell splitting the number of channels, transmitted frequencies

are [ ]

A) Number of channels fixed B) Frequencies Varied C) Both are Varied D) Both fixed

3. When the directional antennas are used the number of principle Interferences is

reduced from [ ]

A) 2 to 6 B) 4 to 2 C) 6 to 2 D) 2 to 4

4. When the C/I received by MU from 120o directional antenna system exceeds 18dB in

Worst cases can improve [ ]

A) S/I ratio B) C/N ratio C) C/I ratio D) All

5. The reduce of interference to the neighboring cells and enhancing the weak spots in

the cell is done by [ ]

A) Antenna pattern B) Antenna tilting C) Antenna Gain D) None

6. During Q calls in an hour, if a call is dropped (Q-1) are completed the call drop rate

Is [ ]

A) Q B) 1/Q C) 2Q D) Q2

7. The voice quality is depends on criteria. [ ]

A) Performance B) Circuit Merit C) A & B D) Communication

8. The diversity scheme is applied at the end of the antenna. [ ]

A) Receiving B) Transmitting C) MTSO D) All

9. Troposphere Reflection occurs due to abrupt change in [ ]

A) Moisture B) Dielectric constant C) Path length D) Angle

10. The duct propagation is also known as

A) trapping B) trooping C) Tracking D) Interference

[ ]

Cont……2

A

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Code No: A107410403 :2: Set No. 1

II Fill in the blanks:

11. The process of automatically changing frequencies as the mobile unit moves into

a different zone is called as

12. The frequency Utilization Measurement in conventional Telephone system is given

by .

13. Frequency reuse in the time domain results in the occupation of the same frequency

In different time slots is called as

14. The effective antenna height varies according to the

15. The other name for Mobile point-to-point model is

16. When the terrain contour blocks the direct wave path, we call it as

17. The capacity of switching equipment in cellular system based on

18. Lowering the antenna height on hill doesn‟t reduce the power at either

Cell site or Mobile Unit.

19. Signal Coverage can be predicted by prediction models.

20. If the Foliage is non-uniform then the path length is

-oOo-










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Code No: N0422 /R07

IV B.Tech. I Semester Regular Examinations, November 2010


(Common to Electronics & Communication Engineering and Electronics &

Computer Engineering)




*******

1. (a) What are the technical difficulties with present wireless communication systems? [8]

(b) What is the significance of propagation, attenuation in mobile radio environment? [8]

2. (a) Explain the concept of frequency reuse channels. [10]

(b) Explain the maximum number of frequency channels per cell. [6]

3. (a) Explain the causes for near to far end interference. [5]

(b) Mention different systems to reduce the interference. [5]

(c) Explain the effect of antenna pattern on the interference at the base station and mobile

unit. [6]

4. (a) What are the different propagation models available for mobile communication,

Explain? [8]

(b) What are the factors influencing the fading of the signal and explain different types of

fading. [8]

5. (a) What do you mean by dead spot in the coverage area? [8]

(b) Describe any two antennas that are suitable at the mobile unit with their important

features and neat sketches. [10]

6. (a) Explain how the channels are assigned in an Omni-directional cell system? [8]

(b) Explain the methods of adjacent channel assignment. [8]

7. (a) What is meant by call drop? Explain and suggest methods to reduce call drop rate. [8]

(b) Write short notes on different types of hand off mechanisms. [8]

8. (a) Explain the architecture of GSM with block diagram? [8]

(b) What are the different services provided by the GSM? [8]

1 of 1

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Set No. 1

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Code No: N0422 /R07




Engineering)




*******

1. (a) Explain the Trunking efficiency? [8]

(b) Explain about the mobile fading characteristics? [8]

2. (a) How the system capacities are related with the co-channel interference, and derive the

expression for signal to interference ratio. [8]

(b) Explain in detail cell splitting concept with neat sketches? [8]

3. (a) Explain the importance of de multiplexer at the receiver to reduce non co-channel

interference? [8]

(b) Explain about typical cell site receiver? [8]

4. Discuss in detail [16]

(a) The propagation in near distance.

(b) Long distance propagation.

5. (a) Draw the pattern for a directional antenna used for interference reduction and explain

how it works. [8]

(b) How the height and separation of an antenna are related in space diversity antennas used

at cell site? Explain. [8]

6. (a) What type of messages is received to the setup channels when mobile unit monitors

strongest signal strength? [8]

(b) What are the advantages of reuse-partition scheme? [8]

7. (a) Explain different hand-off strategies and its importance in different situations? [10]

(b) How to improve call drop rate? [6]

8. (a) Draw the structure of GSM channel and what are the different types of channels present.

(b) Explain the different kinds of bursts used in GSM. [8+8]

1 of 1

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Set No. 2



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Code No: N0422 /R07



(Common To Electronics & Communication Engineering and Electronics & Computer

Engineering)




*******

1. (a) Draw the block diagram of basic cellular mobile communication systems and

explain the function of each block. [10]

(b) What are the spectrum efficiency considerations of an ideal mobile telephone system?

[6]

2. (a) What is hand off ? Describe handoff mechanisms. [8]

(b) Derive the desired C /I for a normal case in an Omni directional antenna systems. [8]

3. Discuss in details the various techniques to measure co channel interference, prove that the

real time co-channel interference measurement is difficult to achieve. [16]

4. (a) Briefly explain the factors considered for prediction of path loss for a particular mobile

radio environment. [8]

(b) If P r = 12W G t =0db G r = 0db and f c = 900MHz. Find P t at a space distance of 1Km

[8]

5. (a) Write the equation of general pattern for a 2N elements array equispaced by a

separation‘d’. [4]

(b) Differentiate between Roof-mounted and glass-mounted antennas. [6]

(c) What are the advantages of using umbrella pattern antennas at cell site? [6]

6. (a) Elaborate dynamic channel assignment and compare its advantages and disadvantages

with the fixed channel assignment? [8]

(b) Write short notes on paging and service channels? [8]

7. (a) Write notes on power difference handoffs. [8]

(b) Explain a two level handoff scheme with suitable example. [8]

8. Write short notes on

(a) Multiplexing and multiple access [10]

(b) CDMA [6]

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Set No. 3



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Code No: N0422 /R07



(Common To Electronics & Communication Engineering and Electronics & Computer

Engineering)




*******

1. (a) What are the technical difficulties with present wireless communication systems? [8]

(b) Distinguish between analog and digital cellular systems. [8]

2. What are the considerations of the components of a cellular system, Explain in detail. [16]

3. (a) What are the different interferences in cellular systems and explain each with diagrams?

[8]

(b) Explain how a diversity receiver reduces the interference. [8]

4. (a) Determine maximum & minimum spectral frequency received from a stationary

transmitter with a central frequency of 1950 MHz , Assume that the mobile receiver is

travelling at speeds of:

i) 1KM ii) 5KM iii) 10KM iv) 100KM [8]

(b) Describe all physical circumstances that relate to a stationary transmitter and a moving

mobile receiver such that the Doppler shift at the receiver is equal to:

i) 0 Hz ii) fd max iii) -fd max iv) fd max/2 [8]

5. (a) Explain the procedure for obtaining sum and difference patterns for antenna systems of

wireless communication? [8]

(b) Write short notes on antenna height and its radiation pattern for mobile unit and its base

station? [8]

6. Explain clearly different channel assignments and its importance in mobile c

communications or in brief frequency management in mobile communications? [16]

7. (a) Explain about the handoff and power control? [8]

(b) Explain about the inter MSC handoff? [8]

8. (a) Draw the internal structure of network and switching subsystem in GSM and explain

the significance of each block. [10]

(b) Write short notes on TDMA. [6]

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Set No. 4



Documents

Question Papers.pdfb) Distinguish between permenant splitting and dynamic splitting. [5+5] OR 3.a) Mention the two frequency reuse schemes and explain N-Cell reuse pattern in detail