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31/1/2010

ME (MSA) Part I Microprocessor in communications

Test

Time: 2 hours. Note: Answer 4 questions in all. Answer each section in a separate answerbook. All questions carry 15 marks, maximum marks for this test:60 ActualTotal marks will be scaled to out-of-15 for the internal marks.

Section I 1. Give the modes of HDLC operation, the frame format and the control field formats, giving the

functions of the field components Give illustrative examples of HDLC operation showing the use of each of the control field components.

2. Write a note on X.25 protocol operation for virtual circuit service and discuss the significance of the

virtual circuit number. 3. Apply Dijkstra’s algorithm to find the least cost paths from node 1 to other nodes in the network

shown below.

1

2 3

4 5

6

1

4

3

1

1 1

2

4

SECTION II

Q 4,5,6


Test December 18, 2000 Time: 2 hours. 1. Answer any 3 questions in section I and all questions in section

II. 2. Answer each section in a separate answer-book. 3. All questions carry 10 marks except when indicated otherwise,

maximum marks :60

SECTION I

Answer any THREE questions in this section 1.Discuss the ISO-OSI model layers and their implementation in data networks.

2.Explain the sliding window protocol. How is it implemented in HDLC?

3.Discuss the differences between message switching, packet switching and circuit switching

4. Discuss the data frame structure and control characters in BISYNCH. Show a typical frame exchange sequence for point to multi-point data exchange using BISYNCH.

SECTION II Answer All questions in this section

5.Short questions: (10 marks)

a) Draw the following data stream in NRZ-L and Manchester Bi-phase -10110100.

b) State the basic difference between RS 232C and RS 422 c) Define physical layer interface. d) What is quaternary signaling? Draw the waveform and coding. e) State the task of the PAD 6.Answer any THREE from the following (8 marks) a) Showing typical routing table entries show how a

virtual channel connection is done. b) Message to be sent is 11001011. The divisor is

11001. Find the CRC4 checksum. Which error detecting method will be able to check the position of the error bit, occurrence of the error and correct it?

c) Show the DTMF keyboard for telephone. What is the specialty in the choice of the frequency?

d) State the A-law. Assuming a constant A, if the peak value is 3 V and current value is 1.2 V, what will be the companded output?

7.Answer any THREE from the following (12 marks) a) Explain what is scrambler and de-scrambler. Why

is scrambling required? Explain with the help of a diagram.

b) What is the minimum phase difference that can be detected on the telephone line signal? Using this explain how higher data rate modems are obtained.

c) What is SPID? How does it help ISDN services? Show also the ISDN primary rate interface frame.

d) i)Show the ATM header cell and the protocol reference model and explain its operation

ii) How amany interconnections are needed for n station PBX?

-END-


Test October 3, 2000 Time: 2 hours. 1. Answer any 3 questions in section I and all questions in section II. 2. Answer each section in a separate answer-book. 3. All questions carry 10 marks except when indicated otherwise, maximum marks :60

SECTION I

Answer any THREE 1. For HDLC, give the frame format and the control field formats, and describe the

functions of the field contents. Give illustrative examples of HDLC operation showing : set up ,data exchange, call termination, flow control and error recovery aspects

2. Explain: ALOHA, slotted ALOHA, non-persistent CSMA, and bit-map reservation protocol

3. Discuss the differences between a) different ARQ mechanisms and b) circuit and

packet switching

4. Explain with reference to BISYNCH :a) point to point communication b) multi-point communication, c) frame structure and d)control characters

SECTION II

5. Short questions: a) Draw the following data stream in RZ and Manchester Bi-phase: 110100010. b) State the basic difference between RS 423 and RS 485 c) Draw the clock recovery circuits and waveform for recovered clock d) State the bandwidth of the B and D channels in Basic Access. e) State the task of the PAD 6. Answer any THREE (8 marks) a) Give the details of the 53 byte cell in ATM, also state the significance of the routing table. b) The message polynomial is X7 + X5 +X3 +X2 and generator polynomial is X4 +X3 +X0. Find the frame check sequence and state how to get it (give diagram) c) The compressed 8 bit code is given by 01001011 Find the original expanded data. d) State the µ -law. If µ = 255what will be the amplitude of output if amplitude of input is 0.8 volts 7. Answer any THREE (12 marks) a) Draw the figure for the physical layer of the Ethernet interface. State different parameters and discuss the Ethernet frame. b) Draw the 16 point constellation for the 9600 bps modem and explain how higher data rates can be achieved for the fixed bandwidth line. c) Draw the generic digital PBX architecture and explain the functions it achieves.

d) Show the interface between Telephone equipment and network for ISDN. What is meant by inverse multiplexing in ISDN?

-END-

ME (Elec) (MSA) Part-1 Test 1 4/9/01

Section I Q1. Short Questions. (5). a) Draw bipolar R-Z for --11010100. b) State voltage levels for 1,0 in 'RS-232. c) What are the three basic blocks of PCM transmitter. d) Define 'group delay. e) What is the necessity of scrambling? Q2. Solve the following. (5). a) A data stream of 11100110 has to use CRC-4.What should the remainder

polynomial? Express in terms of powers of x. Give the scheme. b) State the 'mu' law. Find the input voltage if the digital output was 10111110.

Smallest step size is 0.25mv Q3. Solve any TWO. (5) a) Draw the diagram for T.C.M. transmitter and explain its principle. b) Explain how higher data rate modems are constructed even though the basic

bandwidth remains the same. Draw the diagram for any one type of modem and explain its operation.

c) (i) What are the signals generated under off hook condition? (ii) Explain DTE-DCE interface.

Section II Answer any 5 from the following: Q4: Tabulate differences between packet switching and message switching Q5: A printer is to be shared by 5 computers in the same room. Suggest the topology

and switching technique you will use, giving reasons. Q6: Why is synchronous transmission more efficient than asynchronous transmission? Q7: Is a network layer necessary in a broadcast network? Discuss. Q8: Discuss and differentiate between Data link layer and Transport layer. Q9: In Stop and Wait ARQ What happens when a NACK is lost in transit? Is it

necessary to number the ACKs and / or the NACKs? Why?

-END-

ME (Elec) (MSA) Part-1 Test 1

13/9/05

Section I Answer any 3 from the following: (3 x 5 marks) Q4: Describe differences between packet switching and circuit switching Q5: Discuss routing methods in networks – and give the advantages and

disadvantages of each. Q6: Explain the functions of the various layers in the ISO model. Q7: Differentiate between Stop and wait ARQ and Go Back N ARQ. Describe the

recovery/corrective mechanisms used in Stop and wait ARQ under various error conditions.

-END-

ME (Elec) (MSA) Pt I Microprocessor In communications

Internal Test 8/10/2009 Time 8-30-9-30 am

Maximum marks: 15 Answer any three: Q1. Explain the working of a Time Slot Interchange switch. Give a neat figure in support. Q2. What is the advantage of multistage circuit switching? What is blocking in such a switch? How can it be eliminated? Explain with an example or a diagram. Q3. Explain the Sliding Window protocol with the help of an example / diagram. Q4. Discuss the functions of the layers in the ISO/OSI network architecture

Assignment : (to be submitted before start of Theory examination.)

Maximum marks: 15

Discuss the following aspects of the Internet: (1)TCP and IP headers (ii) Internet addresses (iii) DNS service (iv) Djikstra’s algorithm (v) Internet routing tables.

ME (Elec) (MSA) Part-1 Test 2

29/10/01

Section I

Solve any three.[5 x 3] Q1. a] If the no. of stations to be interconnected are 5,what will be the no.of

interconnections for a fully connected PBX? b] What is hybrid? How and where it is used?

Q2. a] Show the frame relay mapping onto ATM and explain it. b] State the FDM hierarchy.

Q3. a] What is SONET and SONET ADM? b] Draw the ATM protocol reference model and explain it.

Q4. a] What is meant by SPID? b] Explain basic access and primary access in ISDN.

Section II

Answer any 3 from the following: (5 x 3) Q4: Give illustrative examples of HDLC operation showing : link set up ,termination,

busy condition and error recovery aspects Q5: Explain various types of CSMA access control. Q6: Give the functions of the monitor station and A and C bits in the token ring 802.5

LAN. Q7: Use Djikstra’s algorithm to find least cost path from node 2 to node 6. Give the

results of the iterations in a tabular form. Q8: Discuss the assignment of circuit numbers in X.25. Permanent full duplex virtual

circuit connections exist between nodes 1 and 3, and between nodes 1 and 4, the paths being 1−2−3 and 1−2−4. sketch the network, indicating suitable circuit and port numbers and give the tables for each node giving destination, circuit number and port number

-END-

ME(Elec) Pt I (MSA) Test 1

Microprocessors in Communications 14/9/02

Section I

Q1: Solve any three a) Give one feature of each: BUS, RING and HUB Topology. b) Draw Bipolar NRZ and Manchester Biphase for the data stream 11000110, c) Draw the diagram of the Hybrid and state its purpose d) State the bus standard for broadcast mode and give its details (2x3)

Q2:

a) Message Polynomial given is X5 + X4 + X1 + X0. CRC-4 is to be applied. Assume the divisor polynomial and find the total message polynomial to be sent. Draw the scheme.

b) Draw the constellation diagram for a 3 bit modem. 1 bit – amplitude and 2 bit quadrature phase.

c) Compressed digital word in a u-law compander is 11011101. Expand back digitally. If the segment 1 has a step size of 2 mV, what would be the step size in segment 4? (3x3)

Section II

Q3:Answer any Three

a) Distinguish between : i)Message switching and Packet Switching, ii)Synchronous and asynchronous data transmission, iii)Go Back N and Selective Repeat ARQ.

b) Write a note on Time Slot Interchange switching (TSI) c) Write a note on Sliding window protocol. d) Give the functions of the Data link and network layers (3x3)

Q4: In a bisynch point to multipoint system the following events occur in the sequence shown below. Give the diagram showing exchange of the frames, including intermediate supervisory frames and showing frame structures. A selects B and sends two frames of data, B has no frames to send and the link is disconnected. A polls C and C sends two data frames. On receiving C’s data A sends two frames to C C’s acknowledgement for second data frame of A is lost C discovers the error and resends. A sends his last frame to C C sends his last frame to A The link is disconnected. (6x1)

END

ME (MSA) Pt I

1st test: 22/9/99

Microprocessors in communications

Answer any TWO questions Time allowed for this section : 1 hr. Q1 a) Describe the Layer functions for each layer in the ISO-OSI model. b) Give a typical HDLC exchange of frames illustrating

i) Call setup, ii) data exchange iii) error recovery, Explain each sequence of commands (4 + 4 marks)

Q2 a) Explain the main features of the 802.5 LAN. b) Explain with suitable example the operation of the sliding window protocol. (4 + 4 marks) Q3 a) Discuss the different types of ARQ mechanisms for error control.

b) Briefly describe the Aloha and CSMA MAC protocols in their different forms.

Which is suitable for satellite networks ? Why? For ground based radio linked network? Why? (4 + 4 marks)

THE MAHARAJA SAYAJIRAO UNIVERSITY OF BARODA First Semester of ME (Part I) (Electrical) (MSA) Examination

2000 Monday, 1st December Time: 3pm to 6pm

MICROPROCESSORS IN COMMUNICATIONS

N.B.: i) Answer the two sections in separate answerbooks.

ii) Suitable assumptions may be made with due justification.

iii) Attempt FIVE questions in all, but not more than THREE questions from any one section.

iv) Numbers to the right of the questions indicate maximum marks. Unless indicated otherwise, sub-questions carry equal marks

Maximum marks : 70

Section I 1 a):Draw the figure for physical layer of the Ethernet interface. State different

parameters and discuss the Ethernet frame. (6) b):How does the scrambler function? Explain with help of a diagram (4) c): Explain DPSK and its use with WE201 modem. (4)

2 a):What is quarternary signalling in ISDN and why is it used? Explain the

expanded access in ISDN. (5) b): Explain the operation of ATM, give its architecture explaining its header. (5)

c): State the A Law for companding. What will be expanded pattern if compressed code is 11111101 (µ law) (4)

3 a): What does the CLP bit indicate in the ATM Header? (1) b): What is a connection table in PBX? What function does it achieve? Draw

the diagram indicating trunk interface unit and state the function of the control unit in a digital PBX. (7)

c): Draw the Codec transmitter block diagram and explain its operation. (6)

4 a): What is meant by Trellis coding? How is it generated? What it achieves? Draw the diagram of a Trellis coded transmitter and explain how it functions. (8)

b):What is meant by Originate and Answer modem? What is the difference between them? (2)

c): A LRC/VRC is to be done on the following transmitted data block – 3B,1C,2B,3D,4F (all Hex) If received data block is 30,1C,2B,3D,4E is it possible to locate the error? (4)

5 a): Draw the diagram for SNMP-2 managed configuration and explain the

function of each unit. State any one type of PDU and what are its different fields? (6)

b):Explain the function of the adaptive equaliser with the help of a diagram. (4) c): What is a DTMF keyboard? What is the reason for the choice of frequencies? (4)

Section II

6 a) Discuss the operation of the Sliding Window protocol.

b) Comparatively discuss Circuit switching and Packet switching. (14)

-2-

7 a) State the functions of various layers in the ISO model. b) Discuss the functions of the supervisory frames and unnumbered frames in

HDLC. (14) 8 a) Discuss the exchange of BISYNCH frames during a point to multi-point

session b) Explain the sequence of events which result in a full duplex X.25

connection (14) 9 a) Write a note on routing algorithm used by Internet. 10 b) Give the functions of the fields in the TCP header (14)

11 a) Write a note on the initialization procedure of the IEEE 802.4 network

b) Discuss with reference to Internet i) Internet address classification ii) DNS iii) UDP protocol iv) IP Header (14)

END


2001 Thursday, 19th April Time: 3pm to 6pm






Maximum marks : 100

Section I 1 a):What is meant by the physical layer? How physical layer implementation is

done in bus standards of RS-232 and RS 485? b):Draw the following data stream in NRZ-L and Manchester Bi-phase-10110100 (20) 2 a):Differentiate between Basic Access and Expanded Access for ISDN

b): What is meant by a null modem? Why is it required? (20) 3 a): Show the ATM header cell and the protocol reference model & explain its

operation.

b): State the A-law, assuming constant A, if the peak value is 3V, and the sample value is 1.2 V, what will be the companded output? (20)

4 a): Draw the signal space diagram for 9600 bps for V.29 modem and explain the

diagram. b):What is meant by companding? State the µ-Law. (20) 5 a): What is meant by management station and Agent in SNMS and what are their

functions? What are the different types of allowed data models? b):The message to be sent is 11001011, the divisor is 10011. Find the CRC-4

checksum. Which error detecting method will be able to check the position of the error bit and occurrence of the error bit? (20)

Section II 6 a) Explain various routing methods in data networks

b) What is elastic storage? Which switching technologies require this storage? Why? (20) 7 a) How does the ISO model differ from the TCP/IP network? Define and

Discuss the functions of the layers in the TCP/IP network.. b) Explain with examples how the sliding window protocol and error recovery

are implemented in HDLC. (20)

-2-

8 a) Discuss the functions of the various command words in Bisynch and show how

they are used in data exchange between two stations in a point to point situation. b) Write a note on the X.25 header structures (20) 9 a) Briefly discuss the multiple access techniques used in Local Area networks. b) Explain the operation of the Credit mechanism in TCP (20)

10 a) Write a note on priority management in IEEE 802.5 network

b) Define or briefly discuss with reference to Internet or Internetworking i) Router and Gateway ii) Address structure and allocation iii) Highest level applications which use UDP iv) IP Header (20)

END


2001 Tuesday, 27th November Time: 3pm to 6pm





iv) All questions carry equal marks . Maximum marks : 70

Section I 1 a) Explain sliding window protocol. b) Permanent full duplex virtual circuit connections exist between nodes 1 and 3, and

between nodes 1 and 4, and between node 2 and 4, the paths being 1−2−3 and 1−2−4, and 2-4 sketch the network, indicating suitable circuit and port numbers and give the routing tables for each node giving destination, circuit numbers and port numbers.

c) State the functions of the transport layer 2 a) Illustrate BiSynch operation giving frames exchanged during a typical session, for a

point to multipoint configuration. b) Give the main features of ALOHA. Why is slotted Aloha more efficient? c) How does TCP differ from UDP? 3 a) How are routing tables updated in internet routing? Describe giving a suitable

example. b) How are the following problems solved in 802.5 token ring network? i) lost token ii)

orphan frame iii) demands for priority. 4 a) Explain the self learning process in a bridge, Also explain how a spanning tree is set

up. b) Describe internet addressing, and discuss the DNS facility.

Section II

5 Compare and contrast the following:

i) RS 422, RS 485 and 4-20 mA ii) Bipolar NRZ and Manchester Biphase iii) LAN, MAN and WAN iv) ISDN and BISDN

6 a) What is hand-off in cell switching? Explain cell switching in cellular mobiles. What

are the criteria for choosing the frequencies? b) Draw the diagram for descrambler and clock recovery circuit and explain their

operation.

7 a) Give the architecture of ATM cell and explain its header in detail. b) Explain routing table in ATM. 8 a) Draw the diagram of single chip modem and explain its operation. What is a null

modem? b) Explain typical PBX Lan connection with relevant diagram.

END

THE MAHARAJA SAYAJIRAO UNIVERSITY OF BARODA ME (Part I) (Electrical) (MSA) Examination


Page 1 of 2


N.B.: i) Answer the two sections in separate answer books. ii) Each section has one compulsory question. Answer any two out of the

remaining questions in each section iii) Numbers to the right of the questions indicate maximum marks. iv) Maximum marks : 100

Section I

Q1 is compulsory, answer any TWO out of Q2, Q3 and Q4 QUESTION 1: (18) a) Find the equivalent output value for input value of 1 V for µ-law coder whose compressed

peak maximum is 5V. If digital compressed code is 10101001 what will be the expanded 12 bit value?

b) Explain Frame relay frame format and frame relay address format in detail c) Draw the ATM frame and explain the functions of each identifier QUESTION 2: (16) a) What is a hybrid? What is its function? Where are each of the following used in telephone

systems (i) SDM (ii) FDM (iii) TDM ? Why? b) Draw and explain the current loop protocol. Why is it preferred over long distances? QUESTION 3: (16) a) Draw the SONET frame and explain it. Which OSI layers are mapped onto SONET? b) Draw the diagram for ISDN addressing and also its frame and explain both. QUESTION 4: (16) a) Explain the call origination sequence in mobile phones with diagram. What is the use of

ST and SAT. b) Message polynomial is X 8 + X 6 + X 4 + X 2 + 1. Assume a CRC-4 polynomial and find

FCS, also realize it with a diagram.

of 2

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8 5 a) Discuss ARQ methods and state advantages and disadvantages of each. (6) b) Give typical frames exchanged by a network using HDLC for (i) lost ACK

(ii) lost frame and (ii) information exchange (7) c) Discuss the Token Bus LAN. (7)

6 a) Briefly discuss IP addressing and DNS service. (5)

b) Explain the operation of sliding window flow control. (5) c) Differentiate between circuit switched and packet switched networks. (5)

7 a) Explain CSMA/CD and CSMA/CA methods. (5) b) Discuss the structure of the IP header. (5) c) Differentiate between Repeater, Bridge and Router (5) 8 a) Generate the routing table for the network node A in the network shown

below. Link costs are shown for each link in the figure and are same for both directions.

(5) b) Give the functions defined for the layers in ISO – OSI architecture (5) c) Differentiate between (i) Fixed routing and (ii) Internet routing (5)

END

A B

E1

D

C

F1

4

2

5

2

3

3

3 8


2002 Wednesday, 24th April Time: 3pm to 6pm

Page 1 of 2






Maximum marks : 100

Section I 1 a): What is meant by the physical layer? How physical layer implementation is

done in bus standards of RS-232 and RS 485? (12) b): Draw the following data stream in NRZ-L and Manchester Bi-phase-10110100

(8) 2 a): Differentiate between Basic Access and Expanded Access for ISDN (12) b): What is meant by companding? State the µ-Law.. (8) 3 a): What is a connection table in PBX? What function does it achieve? Draw

the diagram indicating trunk interface unit and state the function of the control unit in a digital PBX. (12)

c): Draw the Codec transmitter block diagram and explain its operation. (8)

4 a): What is meant by management station and Agent in SNMS and what are their functions? What are the different types of allowed data models? (12)

c): The message to be sent is 11001011, the divisor is 10011. Find the CRC-4 checksum. Which error detecting method will be able to check the position of the error bit and occurrence of the error bit? (8)

5 a): Draw the signal space diagram for 9600 bps for V.29 modem and explain the

diagram. (8) b):Explain the function of the adaptive equaliser with the help of a diagram. (4) c): Show the ATM header cell and the protocol reference model & explain its

operation. (8)

Section II

6 a) Discuss the Stop and wait ARQ and Go Back N ARQ mechanisms b) Discuss Store and Forward switching. Does a virtual circuit use store and

forward switching? Justify (10+10) 7 a) Discuss the functions of the Session, Network and data-link layers. b) Discuss the format of the information frames and unnumbered frames in HDLC

What are the three HDLC modes? (10+10)

of 2

8 a) Differentiate between Asynchronous and Synchronous communication. b) Write a note on the numbering of virtual circuits in X.25 (10+10) 9 a) Describe the Djikstra’s algorithm with the help of a suitable example.

b) Describe the addressing system used by the Internet (10+10)

10 a) Briefly describe the features of IEEE 802.3 networks b) Discuss

i) CSMA and its variations ii) Bridges and routers (10+10)

END


2002 Saturday, 30th November Time: 3pm to 6pm

Page 1 of 2


N.B.: i) Answer the two sections in separate answerbooks. ii) Suitable assumptions may be made with due justification.

iii) Each section has one compulsory question. Answer any two out of the remaining questions in each section

iii) Numbers to the right of the questions indicate maximum marks. Unless indicated otherwise, sub-questions carry equal marks

Maximum marks : 100

Section I Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4

1 a): What are the different ways by which routing can be achieved in circuit

switched networks? (5) b): Draw the diagram of single chip modem and explain its operation (6) 2 a): Explain MTSO initiated release in cellular receiver. Also state the bandwidths

of mobile transmit and receive channels. What are the parameters which determine the cell size? (12)

3 a): Why is SONET called backward compatible? Explain the layers of SONET and

its frame. (6) b): Draw the diagrams for Trellis coded modulator and explain its function. (6)

4 a): Hamming code has the following check bits: CB0 – 1B, CB1 – 6E, CB2 – B9, CB3 - C7, CB4 – F8 . A 1 in these words indicates the bits for which parity is calculated. The data sent is a block of words from 43 to 48 (ASCII). In the received block the 44 was also obtained as 45. do the error checking correction if possible (6)

b): State the features of message switched data network. (6)

Section II

Q 5 is compulsory, answer any two questions from Q6, Q7 and Q8 5 a) Discuss the IP header and describe the structure and function of its contents. b) Discuss different CSMA methods. (6+5) 6 a) Describe with suitable example / diagram the frames exchanged for connection

establishment, data exchange and connection termination in a typical HDLC connection.

b) Write a notes on i) Bridges ii) UDP and iii) TDM switch. (6+6)

of 2

7 a) Use a suitable routing algorithm to find the routes from node 1 to all other nodes in the following figure. Costs shown are same for both directions.

b) Describe (i) the priority mechanism in the Token Ring LAN, (ii) Call

establishment in X.25 (iii) ICMP (6+6)

8 a) Explain Routing table updating in Internet routing. What is DNS ? b) Discuss (i) Flow control in TCP and (ii) ALOHA and slotted ALOHA (6+6)

END


2003 Friday, 21st November Time: 3pm to 6pm

Page 1 of 2


N.B.: i) Answer the two sections in separate answerbooks. ii) Each section has one compulsory question. Answer any two out of the

remaining questions in each section iii) Numbers to the right of the questions indicate maximum marks. Unless

indicated otherwise, sub-questions carry equal marks Maximum marks : 70

Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): Generate the checksum bytes as per the transport protocol for the following data

bytes 00100110, 11100010, 01010101.Regenerate variables Pl and Ql at the receiving end and show that they are zero if there are no errors. (8)

b): What is meant by frame relay? Show its transmission frame. What technique it uses to reduce network congestion? Explain how its frame is copied on to ATM (7)

2 a): Draw the basic block diagram of a modem and explain its operation. What is

meant by a null modem? Where is it used?

If the constellation diagram contains the following four points (1,1), (1,-1), (-1,1),(-1,-1) and the basic bandwidth of the channel is 9600 KHz, what would be the achieved bit rate? (8)

b): What is STS-1 and DS-1. (2) 3 a): Explain call initiation and call release sequence in cellular mobile. What is meant

by NAM – what is its function? The number of independent frequencies per cell are to be decided. The cell is of pentagon shape and the total number of frequencies is 744. (8)

b): Explain RS 422 and RS 485. (2)

4 What is meant by: a) Synchronous and asynchronous communication (1) b) Baseband and broadband transmission (1) c) Uploading and downloading in a cable modem and their bandwidths (2) d) ADM and DCS in SONET (2) e) NT1 and NT2 in ISDN (2) f) Hybrid in PSTN (2)

Contd…………

of 2

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8

5 a) Discuss circuit switching and compare it with packet switching. b) Discuss the following (i) DNS and (ii) Flooding. (7+6) 6 a) Write notes on i) Frames in HDLC and ii) CSMA methods b) Discuss the 802.5 LAN. (6+5) 7 a) Give typical layers and their functions in a TCP/IP network. Does IP use sliding

windows? Does it use ARQ? Explain. b) Describe the operation of an algorithm to determine least cost paths giving

suitable example. (6+5)

8 a) Write a note on Bi-synch. b) What are the services offered at the network layer? Discuss the routing table . updating process in the Internet. (6+5)

END



Page 1 of 2





Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): Compare circuit switching, message switching and packet switching. (3)

b): Discuss different types of routing in circuit switched network (5) c): If the data block transmitted is 1F,2D,4A,5C and received is 1F,3D,6A,5C

show the process of detection and correction if Hamming code is used (5) d): What is meant by a 1/3 rate convolution encoder? Which bits are used to

generate convolution code? (3) 2 a): What is a frame relay? State the frame relay frame format and explain

frame relay address format. (6) b): (i) What are the multiplexing types used in PSTN and where are they

used? (ii) Explain the function of the SONET switch (2+2)

3 a): What is meant by asynchronous and isosynchronous modes of data transfer in

Firewire? Explain Firewire standard in short? (5) b): (i)Which layers of OSI model are defined for ISDN?Explain only the network

layer. (ii)Explain the function of the Hybrid in PSTN. (3+2)

4 a):Explain the call initiation sequence from a land line to a mobile (5) b): (i)What is the purpose of ADM and Dual Ring in Sonet?

(ii) What is a PBX bridge? (iii) Explain IrDA standard in short (1+1+3)

….contd

of 2

Section II


5 a) Highlight the similarities and differences between (i) Sliding window and Credit

allocation in TCP, (ii) Go back N and Selective repeat ARQ. b) Explain the (i) X-Modem data link protocol and (ii) Djikstra’s algorithm. (7+7) 6 a) Discuss the (i) Priority and Reservation mechanism in Token Ring LAN (ii)

differences between various CSMA medium access protocols. b) Write notes on i) Routers and Gateways ii) X-25 channel allocation strategy.

(5+5) 7 a) Discuss the (i) TCP timers and (ii) UDP header giving significance and functions

of each constituent. b) Generate the routing table for the network node 3 in the network shown

below. Link costs are shown for each link in the figure and are same for both directions. (5+5)

1

2

4 5

3

611

32

1

4 14

8 a) Comment on (i) the working of the DNS system and (ii) classification of internet addresses

b) Write notes on (i) Unnumbered frames in HDLC and (ii) Application layer protocols in the Internet (5+5)

END


2005 Tuesday, 12th April Time: 3pm to 6pm

Page 1 of 1





Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): What are the two basic techniques for switching data units? Explain in brief. (10)

b): What is meant by the physical layer? How physical layer implementation is done in bus standards of RS-232 and RS 485? (10)

2 a): Differentiate between Basic Access and Expanded Access for ISDN. (8) b): Explain the ATM header cell. (7) 3 a): Draw the diagram of single chip modem and explain its operation (9)

b): Give two features of each: (i) Bus, (ii) Ring and (iii) Hub topology. (6)

4 a): Why is SONET called backward compatible? Explain the layers of SONET and its frame (8)

b): Draw the diagrams for Trellis coded modulator and explain its function. (7)

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8 5 a) Discuss packet switching and compare it with message switching. b) Discuss the following in brief (i) network layer (ii) UDP and (iii) Flooding. (9+9) 6 a) Discuss the 802.4 LAN. b) Write notes on i) Unnumbered and supervisory frames in HDLC and ii) ALOHA (8+8) 7 a) What is the sliding window protocol? Explain giving an example of its operation. b) Describe an algorithm to determine least cost paths giving suitable example. (8+8)

8 a) Discuss point to multipoint communication using Bisynch.

b) Discuss the IP header and give the significance of the various fields. (8+8)

END


2005 Tuesday, 29th November Time: 11am to 2pm

Page 1 of 2





Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): What is meant by multi-drop communication? Which bus standard achieves this?

Give the specifications for such a bus standard. (3) b): What are the extra services provided by the digital PBX? Will the PBX reduce

the number of interconnections? Justify. (3) c): A modem has 64 constellation points. It sends them 10000 times/second.

Calculate its bit rate and baud rate. What will be the maximum data rate of the channel if signal to noise ration is 15 (3)

d): Show that fold-over can be avoided by proper sampling? (3) e): State the frame relay format and differences between X.25 and frame relay (3)

2 a): Explain the SONET frame and layer structure Explain the statement that SPE

need not be aligned to any STS-1 frame. (8) b): What are the functions of the control channels in cellular mobiles (2)

3 a): State the telephone equipment interface to ISDN network. How is this extended

to BISDN? What is the basic “header” structure? Explain the Header significance. Justify the statement that latency in BISDN is reduced as compared to traditional LAN. (8)

b): Justify the statement that station codes of different receivers in CDMA are orthogonal (with example). (2)

4 a): State the features of a 4G mobile. Explain the functions of IWF,HLR,VLR, and

functional planes of GSM (8) b): Draw the ATM switch entries and write the routing table for these entries. (2)

….contd

of 2

Section II


5 a) Briefly discuss (i) X Modem (ii) Stop and Wait ARQ and its efficiency (8) b) Describe the X.25 virtual circuit numbering system and the circuit set-up and

release procedures. (7) 6 a) Briefly discuss the (i) TDMA switch (ii) IP Header. (6)

b) Explain the procedures used in CSMA/CD, with the help of a block diagram (4) 7 a) Discuss the (i) Binary exponential back-off and (ii) ALOHA (6) b) Generate the routing table for the network node A in the network shown

below. Link costs are shown for each link in the figure and are same for both directions. (4)

8 a) Discuss (i) Internet addresses and (ii) Internet routing (6) b) What are the HDLC frame types? Describe briefly. Give suitable examples of data

exchange showing their use. (4)

END

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Page 1 of 2





Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): Draw thw block diagram and constellation diagram of 16 QAM modulator and

explain its function. (6) b): Find the equivalent output value (compressed) for the input value of 2V and

whose peak value is 5 V for the u-law decoder. (6) c): Explain the functional planes of GSM and their functions (6)

2 a): State of on-hook and off-hook voltages od a telephone. Explain the 30 channel

PCM frame and digital hierarchy upto order 3 . (10) b): Show the frequency allocation in a typical CATV system and state reasons for the

bandwidth allocation. (6) 3 a): Draw the SONET frame structure and explain an individual frame. Which layers

of OSI are functional in SONET? How?. (10) b): Compare RS 232 and RS 422 Standards. (6)

4 a): Explain the Frame relay architecture and explain the congestion control in frame relay. (10)

b): Message polynomial is X5 + X3 + X1 + 1 and generator polynomial is X4 + X3+1. Find the frame check sequence. Explain how it detects any error? Is it FEC or REC? Why? (6)

….contd

of 2

Section II


5 a) Discuss Stop and Wait ARQ and find the expression for its efficiency (10) b) Explain differences between (i) Virtual circuits and datagrams

(ii) WAN and LAN (8) 6 a) Briefly discuss the (i) slotted ALOHA system (ii) IP addressing. (8)

b) Explain the operation of (i) p-persistent CSMA and (ii) CSMA/CD (8) 7 a) Describe the important features of the Token Ring LAN. (8) b) Write a note on Djikstra’s algorithm and explain how it works with help of a

suitable example (8)

8 a) Discuss layers in TCP/IP networks. How does TCP/IP differ from ISO-OSI model? (8)

b) Write a note on HDLC frames and their use. (8)

END



Page 1 of 2




Section I

Q1 is compulsory, answer any TWO out of Q2, Q3 and Q4 QUESTION 1: a) Draw and explain the frame relay frame format and frame relay address format. What causes congestion in frame relay and how is it removed? (7) b) Explain the transport protocol in generalized form and generate the checksum bytes for the following data bytes: 46,23,71,BC (take binary equivalent for each digit) and explain. (8) QUESTION 2: (10) a) Draw and explain the diagram of a typical PCM system and show that band-limiting filter is essential at the input. b) What are the features of SONET? What are the different layers? State the names of

components used in SONET and explain their functions. QUESTION 3: (10) a) What are the functions of digital PBX? What is meant by connection table? b) What is the basic difference between GSM and CDMA? Explain with an example. What are the layers of GSM? State their functions. QUESTION 4: (10) a) What is ATM? Draw its frame and explain it. How is it better than the traditional LAN? b) What are the different accesses in ISDN? Differentiate between them. State ISDN address

structures

of 2

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8 5 a) Discuss Stop and Wait ARQ and obtain an expression for its throughput

efficiency. (5) b) Give typical frames exchanged by a point to multipoint network using BISYNCH

for (i) polling, (ii) information exchange (iii) busy condition (iv) lost frame (5) c) Explain the differences between TDMA, ALOHA and CSMA. State the conditions

when each cannot be used, giving a suitable example. (5) 6 a) Briefly discuss the layers used by the networking service provider’s equipment in

the ISO-OSI architecture. (5) b) Explain the operation of sliding window flow control. (5)

7 a) Describe the various routing strategies used in networks. (5) b) Discuss HDLC and give typical HDLC frames exchanged under following

conditions: (i) lost frame and (ii) lost ACK (5) 8 a) Discuss how the least cost path may be found in a multi route network. Give an

illustrative example. (5) b) Discuss the 802.4 LAN features (5)

END


2008 Time: 3pm to 6pm

Page 1 of 2





Section I

Q1 is compulsory, Solve any TWO out of Q2, Q3 and Q4 1 a): Draw thw block diagram and constellation diagram of 16 QAM modulator and

explain its function. (6) b): Find the equivalent output value (compressed) for the input value of 2V and

whose peak value is 5 V for the u-law decoder. (6) c): Explain the functional planes of GSM and their functions (6)

2 a): State of on-hook and off-hook voltages od a telephone. Explain the 30 channel

PCM frame and digital hierarchy upto order 3 . (10) b): Show the frequency allocation in a typical CATV system and state reasons for the

bandwidth allocation. (6) 3 a): Draw the SONET frame structure and explain an individual frame. Which layers

of OSI are functional in SONET? How?. (10) b): Compare RS 232 and RS 422 Standards. (6)

4 a): Explain the Frame relay architecture and explain the congestion control in frame relay. (10)

b): Message polynomial is X5 + X3 + X1 + 1 and generator polynomial is X4 + X3+1. Find the frame check sequence. Explain how it detects any error? Is it FEC or REC? Why? (6)

….contd

of 2

Section II


5 a) What is multi stage circuit switching? What are its advantages? What is the

condition for a three stage switch to be non- blocking? (5) b) Discuss the sliding window protocol (5) c) Explain the IP header. (5) 6 a) Briefly discuss the (i) Link setup and disconnect, (ii) Data exchange and (iii) Error

correction procedures in HDLC. (5) b) Explain the operation of Bit Mapped reservation Access (5)

7 a) Describe the Go Back N ARQ method and analyze it for throughput, giving

necessary derivations. (5) b) Discuss the 802.5 reservation mechanism. (5)

8 a) Discuss layers in ISO-OSI architecture. What is the difference between the error

detection/correction in the network resident layers and the host resident layer? (5) b) Explain Internet routing table and its updating.. (5)

END


2009 Saturday, 11th April Time: 3pm to 6pm

Page 1 of 2



remaining questions in each section iii) Numbers to the right of the questions indicate maximum marks.

Maximum marks : 100

Section I

Q1 is compulsory, answer any TWO out of Q2, Q3 and Q4 QUESTION 1: a) (7) b) (8) QUESTION 2: (10) a). b). QUESTION 3: (10) a) b) QUESTION 4: (10) a) b)

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8 5 a) Compare and contrast (i) Stop and Wait and (ii) Selective Repeat ARQ and

obtain an expression for the throughput efficiency of stop & wait ARQ. (6)

of 2

b) Discuss the BISYNCH frame formats. Does BISYNCH implement ARQ? Piggybacking? Sliding window protocol? Explain. (6)

c) Explain the non-persistent CSMA and p-persistent CSMA. (6) 6 a) Briefly discuss the layers used by the ISO-OSI architecture. Differentiate

between link errors and end to end errors (8) b) Explain the operation of 802.5 LAN (8)

7 a) Explain the ALOHA and slotted ALOHA methods of medium access. (8) b) Discuss HDLC and give typical HDLC frames exchanged under following

conditions: (i) Information exchange and (ii) lost ACK (8) 8 a) Describe Djikstra’s algorithm. Give an illustrative example. (8)

b) Discuss the IP Header in detail. (8)

END


1997 Monday, December 1 Time: 3pm to 6pm




iii) Attempt FIVE questions in all, but not more than THREE questions from any one section. All questions carry equal marks.

Maximum marks : 100

Section I 1 a):Describe the CRC technique for error detection, and give the block diagram for an

error detection circuit using CRC-4, which is represented by the polynomial X4 +X1

+1 b): Select the error detection method you would usefor the conditions stated below, and

justify your choice: 1)direct memory transfer of data from Floppy disk to the computer

RAM 2)Bulletin Board messages via phone lines to a home PC 2 a): Explain: Asynchronous and Synchronous transmissions. b): Explain the main differences between RS 232C and RS 449. . 3 Describe the opration of the Motorola ACIA. 4 a):Briefly describe the operation of the Time Slot Interchange (TSI) switch.

b):Explain why High speed modems use combinations of FSK/PSK and ASK.

5 a):Distinguish between Packet Switching and Circuit switching. b):Briefly enumerate the signals required at the digital interface between a modem and

the DCE, and state their functions..

Section II 6 a):Explain the functions of the various layers in the ISO-OSI model b): Distinguish between Connectionless and connection oriented services 7 Describe theIEEE 802.3 standard for Ethernet LAN 8 a):Explain the Sliding Window flow control mechanism. b):Mention some of the commands and responses conveyed by the Un-numbered type of

frame in HDLC 9 a)Describe the general packet format for the X.25 interface. What is a PAD? When is it

required?

-2-

B): Explain the functions of the SNIC, SNDC and SNAC sublayers within the network layer

10 a) Differentiate between a Bridge and a Gateway. b) Briefly discuss Internet protocol (IP)

END


1998 Monday, 23rd November Time: 3pm to 6pm





Maximum marks : 70

Section I 1 a):Discuss the General implementation of the CRC technique using Ex-Or gates and

shift registers. If the message is X9 + X7 + X3 + X2 +1, and the CRC polynomial is X5 + X4 + X2 +1, give the shift register implementation and find (by any suitable method) the FCS. b): Describe the 8251A USART mode-setting and command instruction words. Also

describe the contents of its status register with brief explanations. 2 a): Explain with figures showing important aspects of the commands/responses/frames

exchanged during the following events in HDLC operation. i) Link set up and disconnect ii) Two way data exchange iii) One terminal in a busy condition. iv) Error due to packet loss and error recovery.

b): Discuss the handshake signals in RS 232C. What is a null modem? . 3 a): Write a note on the Virtual circuit numbering in X.25. Describe a typical sequence of

events in a virtual call. b): Use a suitable least cost algorithm to find the least cost path and least cost from node

3 to all other nodes in the network shown in the figure below. The numbers next to the arrows indicate link costs in the direction of the arrow. Double headed arrows indicate same cost in either direction. Node numbers are given in the node circles.

1

2

4 5

3

613

3

3

1

31

31

1 4

3

2

-2-

4 a): Discuss addressing scheme in the Internet Protocol (IP) and give the details of the IP

Header with brief explanations of the fields or their contents.. b): End System A on a 802.4 LAN communicates with another End System B on a 802.5 LAN via a X.25 packet network. Explain how the exchange occurs giving the involved layers and packet formats

5 a):Explain the Credit allocation mechanism in TCP for flow control. b):Briefly discuss the various protocols implemented in the Internet, which form a part

of the TCP/IP suite.

Section II 6 a): What will be the transmitted phase for the bit stream 10011100 in case of BPSK and

QPSK modulations? Explain how ambiguity resolution is done using differential BPSK modulation.

b): Briefly explain with block diagram the generation of QAM. 7 Write a short note on i) ISDN and ii) Wireless LAN. 8 Discuss i) Synchronous TDM for 2MB/s stream and ii) Statistical TDM. 9 Explain different LAN topologies and describe the media access control for CSMA/CD 10 a): Describe the ATM cell structure. Explain how cell relay switching is done..

b): Briefly discuss the differences between circuit switching and packet switching technologies.

END


1999 Monday, 5rd April Time: 3pm to 6pm





Maximum marks : 100

Section I 1 a):Discuss the implementation of the CRC technique using Ex-Or gates and shift

registers for the CRC polynomial X16 + X 12 +X 5 + 1. b): Describe the ACIA control register contents. Also describe the contents of its status

register with brief explanations. 2 a): Discuss with suitable diagrams the operation of HDLC giving the

commands/responses/frames exchanged during a typical session. b): Write a note on synchronous transmission.. 3 a): Distinguish between Stop &Wait, Go Back N and Selective Repeat ARQ flow

control. b): Use a suitable least cost algorithm to find the least cost path and least cost from node

1 to all other nodes in the network shown in the figure below. The numbers next to the arrows indicate link costs in either direction. Node numbers are given in the node circles.

1

2

4 5

3

611

32

1

4 14

4 a): Discuss the sliding window mechanism. b): Discuss the X.25 header format. 5 a):Discuss the BGP protocol. b):Briefly discuss the differences between the bridge, the router and gateway

Section II

6 a): Describe various widely used LAN topologies. b): Explain IEEE 802.3 LAN standard protocol along with the random access technique. 7 Explain with aid of block diagrams various stages of voice signal processing in an

electronic automatic exchange. 8 Write short notes on i) STAT MUX and b) Wireless LAN. 9 Describe the the network between the user and the exchange in ISDN. What are the

different services offered by ISDN? 10 Describe with block diagrams the different modulation schemes for digital data

transmission.

END


1999 Monday, 22nd November Time: 3pm to 6pm





Maximum marks : 70

Section I 1 Give the detailed block diagram of ACIA, indicating each block and line. State and

describe each field of the ACIA control register, What Hexadecimal data are sent to ACIA control register to configure it to handle ASCII asynchronous data with ODD parity and 2 stop bits? Disable both interrupts and assert RTS. Use a divide ratio of 16

2 What is RS232C? Describe its various pin functions in detail, and give voltage levels

for transmission and reception Discuss a typical sequence of signals exchanged during Asynchronous Private line communication and during an over the telephone link.

3 a): Discuss the INTEL 2970 modem giving functional blocks. b): Write a note on X.21. Compare it with RS232C

4 a): Describe the following 82586 action commands stating status word and command word for each (i) NOP (ii)IA-SETUP (iii)TRANSMIT (iv)TDR.

b): Discuss mode setting and command instruction words of 8251A USART.

5 a): Discuss the X.25 virtual circuit numbering system b):Discuss the functions and operation of the Bridge. How is a Spanning tree established?

Section II

6 a): Write a note on the synchronous data link protocols. b): Give the frame structures in BiSYNCH for the following sequence of data exchange

A selects B, B is not ready for data A Retries, B is now ready to receive A sends 1st frame, B acknowledges A sends next frame, B detects error, informs A A Resends, B acknowledges, but acknowledgement is lost A and B take appropriate corrective action A sends last frame, B acknowledges.

-2-

7 Describe the algorithm for the determination of the least cost paths in data networks.

Use the algorithm to find least cost paths from node D to all other nodes in the above figure 1: All links are bi-directional, and costs shown are same for both directions

8 Write short notes on Data link layer in LANs and its sub-layers. 9 a) Discuss Internet routing mechanism.

b) Discuss the IP packet format and state the functions of the different fields in it.

10 Discuss the functions of the various timers in the TCP protocol. How is TCP flow control different from the Data Link layer flow control?

END

A B

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Fig. 1


1999 Monday, 22nd November Time: 3pm to 6pm





Maximum marks : 70

Section I 1 2

3 a):.

b):

4 a):. b):.

5 a): Write a note on X.25 b):Discuss the functions and operation of the router.

Section II

6 a): Discuss the types of frames defined in HDLC b): Give the frame structures in BiSYNCH for the following actions during data

exchange A selects B, B is not ready for data

A sends a frame, B detects error, informs A A sends last frame, B acknowledges.

7 Discuss least cost routing and explain how routing is updated in the Internet Protocol 8 Write short notes on Medium Access Control in LANs and WANs. 9 a) Discuss ring initialization, lost token handling and priority mechanism in 802.5

networks b) Discuss the IP header format,

10 Discuss the credit allocation mechanism in the TCP protocol. Give the typical layer structure of the Internet and discuss some of the higher level protocols.

END


1997 Time: 3pm to 6pm

MICROPROCESSORS IN COMMUNICATIONS N.B.: i) Answer the two sections in separate answerbooks.



Maximum marks : 100

Section I 1 a):Describe Data Formats and Addressing. b):What is a datagram header? Explain in detail the formatted contents of a datagram.

2 a): Which are the devices used for networking? b): Explain different types of repeaters. . 3 a):Describe ATM Multiplexing.

b):Explain in detail the various functions performed at the ATM layers. 4 a):Why is FDDI inherently reliable?

b):What are the principle features of FDDI? c):Explain “Connection oriented” and “connectionless” communications models.

5 a)What are LAN and WAN? Which are the elements which make up a LAN? b)Describe in detail the seven layer ISO/OSI model.

Section II

6 a)Write a note on modems. b)Explain the handshake signal sequence between DTE and DCE in RS232C. 7 a) Briefly discuss the error detection techniques typically used in data communications. b) Discuss routing methods in Data Communication networks. 8 a)Explain the main features of the Stop-and-Wait and Go-Back-N flow control

algorithms. (8) b)Differentiate between the ALOHA and CSMA multiple access protocols.

Which is more suitable for Packet radio networks? For Packet VSAT network? (8) 9 a)What are the features of the different frame types in HDLC? b)Describe the salient features of a Token Bus network. 10 a)Explain the function of the “SET SUCCESSOR” and “WHO SUCCEEDS” Tokens. b)Write a note on Ethernet .

-2-

END



Page 1 of 2




Section I

Q1 is compulsory, answer any TWO out of Q2, Q3 and Q4

QUESTION 1: (18) a) Find the equivalent compressed output value for input value of 1 V for µ-law coder

whose peak maximum is 5V. If digital compressed code is 10101001 what will be the expanded 12 bit value?

b) Explain Frame relay frame format and frame relay address format in detail. c) Draw the ATM frame and explain the functions of each identifier. QUESTION 2 (16) a) What is a hybrid? What is its function? Where are each of the following used in

telephone systems (i) SDM (ii) FDM (iii) TDM ? Why? b) Draw and explain the current loop protocol. Why is it preferred over long distances? QUESTION 3: (16) a) Draw the SONET frame and explain it. Which OSI layers are mapped onto SONET? b) Draw the diagram for ISDN addressing and also its frame and explain both. QUESTION 4: (16) a) Explain the call origination sequence in mobile phones with diagram. What is the use of

ST and SAT. b) Message polynomial is X 8 + X 6 + X 4 + X 2 + 1. Assume a CRC-4 polynomial and find

FCS, also realize it with a diagram.

of 2

Section II

Q 5 is compulsory, answer any TWO questions from Q6, Q7 and Q8 5 a) Discuss ARQ methods and state advantages and disadvantages of each. (6) b) Give typical frames exchanged by a network using HDLC for (i) lost ACK

(ii) lost frame and (ii) information exchange (7) c) Discuss the Token Bus LAN. (7)

6 a) Briefly discuss IP addressing and DNS service. (5)

b) Explain the operation of sliding window flow control. (5) c) Differentiate between circuit switched and packet switched networks. (5)

7 a) Explain CSMA/CD and CSMA/CA methods. (5) b) Discuss the structure of the IP header. (5) c) Differentiate between Repeater, Bridge and Router (5) 8 a) Generate the routing table for the network node A in the network shown

below. Link costs are shown for each link in the figure and are same for both directions.

(5) b) Give the functions defined for the layers in ISO – OSI architecture (5) c) Differentiate between (i) Fixed routing and (ii) Internet routing (5)

END

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Page 1 of 2


Note: i) Answer the two sections in separate answer books. ii) Each section has one compulsory question. Answer any two out of the

remaining questions in each section iii) Numbers to the right of the questions indicate maximum marks.

Maximum marks : 70 Section I

Q1 is compulsory, answer any TWO out of Q2, Q3 and Q4

QUESTION 1: a) Draw the OSI model. State the functions of each layer. Which layers are represented in

ISDN? State the ISDN addressing. What services are provided by ISDN? (5) b) Generate the checksum bytes as per the transport protocol for the following data bytes:

10100101,00100110,11100010,00001111 (6)

QUESTION 2: a) What are the SONET layers? What is the equivalence with OSI layers? Describe the basic

frame. Which bytes represent that SPE is floating? (5) b) What are the functions of HLR and VLR? Draw the sub-system diagram in which they are

located and explain the subsystem interfaces. (4) c) The basic bandwidth of the system is 100kHz. 16QAM modem is used. Draw the

constellation diagram. What will be the data rate? (3) QUESTION 3: a) What is meant by the Hamming Distance? How does it help in error correction? Explain

with an example where the distance is 6. (5) b) State the header structure of ATM and also draw its protocol refere nce model. Explain

both where and why ATM is preferred. (4) c) Four signals 100 Hz, 100 Hz, 200 Hz and 400 Hz are to be multiplexed What are the

different ways of multiplexing? What will the multiplexed data rate be if all channels are sampled at Nyquist rate? (3)

QUESTION 4: a) Explain call origination sequence in AMPS. What is meant by SAT color code? What are

the functions of ST and SAT. (5) b) In CDMA scheme the station codes of A and B are 10101 and 11100. What would be

received at receivers when both the stations are transmitting bit ‘0’. Explain the process. (4)

c) Compare current loop and RS 485 protocols. (3)

of 2

Section II


5 a) Write a note on virtual circuits and datagrams (3) b) Explain why multi-stage switching is preferred in circuit switching giving an

example of a three stage switch. What is blocking? What is the condition for the switch in your example to be non-blocking? (3)

c) With the help of a neat diagram explain the operation of a TDMA switch (3)

6 a) Discuss the ARQ methods of error control. (6)

b) Describe the main features of the IEEE 802.3 Ethernet network. How does the LAN Data-link layer differ from that of other types of networks? (7)

7 a) What is the difference between ALOHA and CSMA? Also Explain the

difference between persistent CSMA , non-persistent CSMA and p-persistent CSMA (6)

b) Explain the working of the sliding window mechanism for flow and error

control. Assuming a three bit packet numbering, can the maximum window size be 8 packets? Justify your answer. (7)

8 a) Write a note on HDLC, giving examples of its operation. (6)

b) Discuss the Internet Address classification and the Domain Name Service (DNS) (7)

END

THE MAHARAJA SAYAJIRAO UNIVERSITY OF BARODA ME (Electrical) (MSA) Part-I examination

2006 Tuesday, November 21 3 PM to 6 PM

Microprocessor in Communications

N.B.: i) Answer the two sections in separate answer-books. ii) All Questions unless otherwise specified carry equal marks. iii) All symbols carry usual significance. Make suitable assumptions wherever required,. Maximum marks: 70

SECTION I

Note: Q1 is compulsory. Solve any two out of Q2, Q3 and Q4 Q1: a) Draw the basic block diagram of PCM transmitter. Show the processing of 3V (peak

amplitude) voice signal if compression used is analog. Explain the selection criteria at each block in detail (6)

b) Block of data transmitted is 60,43,70,12 and received is 60,43,71,13 (these are BCD equivalents) Show the process of error detection using checksum method. (6)

c) For a cable modem show the frequency allocation and how data, voice and TV could be sent over the cable. (3)

Q2: a) Explain the ATM header in the ATM cell. Why is it said that SONET can carry ATM cells. Explain with the help of frame. (5)

b) Show the OSI layer representation in ISDN. (2) c) Explain call release mechanism in mobile. (3)

Q3: a) Compare SIM and NAM and their importance in the individual scheme. (4) b) Show that VLR and HLR subsystems in the system diagram and state their functions(4) c) Explain the function of ATM switch and packet processor. (2)

Q4: a) What are the types of multiplexing in telephone systems? What is the role of hybrid?

A constellation diagram of a modem has 32 points. What will be the data rate if maximum bandwidth of the medium is 100 KHz. (4)

b) All OSI layers need not be defined for every network. Explain with the help of PSTN and Frame Relay. (4)

c) What are the different tones that are used in AMPS? What is the function of each? (2)

SECTION II Attempt all questions in this section

Q5: a) What is Flow Control? Explain Sliding Window flow control in detail. (5) b) What are switching techniques for a switching node. Explain any one in detail. (4) Q6: a). What is Packet Switching ? Explain in detail. (5) b). Explain Dijkstra’s algorithm with an example. (5)

OR

a). What is X.25 protocol ? Explain the sequence of events for communication using

the X.25 protocol. (5) b). State the importance of Bridges. and explain the Spanning Tree Algorithm. (5)

2 Q7: a). Write a note on IEEE 802.3 protocol (6) b). Explain LAN protocol architecture. (4)

OR

a). Explain FDDI protocol. How is it different from token ring? (6) b). Write a note of Data Link layer of LAN. Why is it modified for LAN? (4)

Q8: Write a note on Internet addressing. (6)

OR

a). Explain the IP protocol. (4) b). Write a note on DHCP. (2)

--END--

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