B5.3-R3: NETWORK MANAGEMENT & INFORMATION SECURITY Jan 2006

1.

a) What is digital signature? Which algorithms are used for digital signatures?

b) Differentiate between steganography and cryptography.

c) How does message digest help in checking the integrity of a transmitted text?

d) State four primary functions of CERT.

e) Differentiate between active and passive attacks on a computer.

f) What is an application level firewall and why is it necessary?

g) State any four acts amounting to “cybercrime” as per IT Act 2000.

(7×4)

2.

a) Suppose you are doing RSA encryption with the prime numbers p=13 and q=7. Also, assume that encryption exponent e=5. Find the least positive decryption exponent d. Next, encrypt the message m=7. Now decrypt the cipher c=2.

b) Explain the distributed DoS (Denial of Service) attack with a suitable diagram? Why is this kind of attack very common during the final hours of the Internet auction?

c) What is the importance of “no read up” plus “no write down” rule for a multilevel security system?

(9+6+3)

3.

a) What is meant by IP spooling? How can a router be used to prevent IP spooling?

b) How does RSA based digital signature help in “non-repudiation”? Explain with a concrete example scenario between a sender and a receiver.

c) Describe the Digital Signature (DS) Algorithm based on DS standard of NIST. How are signing and verifying done in DS standard?

(3+6+9)

4.

a) Consider the following threats to Web security and describe how each is countered by a particular feature of SSL (Secure Sockets Layer):

i) Brute-Force Cryptanalytic Attack

ii) Replay Attack

iii) Packet Sniffing

iv) Password Cracker

v) SYN Flooding

vi) Man-In-The-Middle Attack

b) Name the six participants in the SET system and show their interconnections in a secure electronic commerce component diagram.

([6x2]+6)

5.

a) In most of the campus/corporate networks, we find firewalls preceded by a router, but not the reverse. Can you explain why this has become almost a de-facto standard?

b) What is the difference between “reactive” and “proactive” fault management? State the four steps usually followed in reactive fault management.

c) What does SNMP define as manager, agent and client? Why does SNMP need SMI and MIB to manage a network? How are they related to UDP?

(3+6+9)

6.

a) Describe briefly the Bell-La Padula Model and its limitations. What is tranquility principle in this model?

b) What are the three classes of intruders? Discuss any three metrics used in profile-based anomaly detection. Explain the architecture of a distributed intrusion detection system (with a suitable diagram) and name the various components.

(8+10)

7. Write short notes on any three:

i) Pretty Good Privacy (PGP)

ii) IPsec VPN

iii) Risk Assessment (RA)

iv) Biometrics

(3×6)

B5.2-R3: OBJECT ORIENTED DATABASE MANAGEMENT SYSTEMS Jan 2006

1. Briefly explain the following:

a) Compare object oriented design with procedure-oriented design.

b) Define classes, abstract classes and interfaces and explain their utility.

c) What is meant by separation of interface and implementation in object-oriented design?

d) Distinguish between coupling and cohesion. Which is encouraged by object-oriented technology?

e) Distinguish between a function call and message dispatch.

f) Distinguish between method overloading and method-overriding.

g) Explain static and dynamic binding.

(7×4)

2.

a) Define inheritance relationship, composition relationship and association relationship in object-oriented technology. Also define and discuss their role in system development.

b) Explain single and multiple inheritances and how Java supports them. Illustrate with suitable examples

c) Define inheriting rule, subtype rule and method selection rule. Explain with examples.

(6+6+6)

3.

a) Distinguish between procedural programming paradigm and object-oriented programming paradigm. What are the benefits of object-oriented programming over procedural programming?

b) Explain static and dynamic polymorphism with suitable examples.

c) Explain abstraction and encapsulation concepts in object-oriented technology with a suitable example. Can abstraction and encapsulation be achieved in C programming language? If yes, then illustrate with an example in C otherwise explain.

(4+6+8)

4.

a) What is OMG? Explain in brief.

b) What is an ORB and what are its functions?

c) What is CORBA? Give a brief explanation about the CORBA and its architecture.

d) What are CORBA services? Explain with some example.

(3+3+6+6)

5. Consider the following details of a database system, which is required by an academic institute to automate many of its administrative activities. Carryout the questions (a), (b) and (c) listed below:

- The database system caters to the needs of three types of members – faculty, student and staff members.

- All members have a name (string), an address (string) and an Id (integer). In addition, faculty-members have a few research interests (an array of strings) and Office-telephone number (integer); student-members have an academic program number (integer) and staff-members have an employee-number (integer).

a) Identify the features of the above systems, which would help in object-oriented design.

b) How the above object-orientation can be supported in SQL? List the characteristic features of SQL to deal with object-orientation.

c) Create an object-oriented database schema definition for this database.

(6+6+6)

6.

a) What is object serialization? How is the concept linked to object-persistence? How does a persistent programming language help in object-oriented databases?

b) Differentiate between a relational database and object-relational database models.

c) Using description given in question 5, describe how does the concept of an object in the object-oriented model differ from the concept of an entity in the entity-relationship model?

(6+6+6)

7.

a) How are large objects such as multimedia objects are stored in object-oriented database systems? Explain in details.

b) If an object is created without any reference to it how can it be deleted?

c) Distinguish between relational database and object-relational database models.

d) Explain in brief the features of deductive databases.

(6+4+4+4)

B5.1-R3: PROFESSIONAL AND BUSINESS COMMUNICATION Jan 06

1.

a) ‘Needless repetition of words and ideas add to the length of sentences without contributing to their meanings. Therefore, avoiding repetition of words and ideas enhances the effectiveness of the communication.’ In the light of this statement, write down sentences to eliminate repetition of words and ideas shown in italics from the following statements:

i) We must assemble together at 10:30 AM in the morning.

ii) If you are not satisfied, then return it back to us.

iii) One should understand the basic fundamentals of clear writing.

iv) We should plan in advance for future.

b) State whether you agree or disagree with the following statements:

i) Most of the oral communication in an organisation is informal.

ii) In an organization, oral communication as a means of formal communication is more effective than written communication.

iii) Rules of communications are same whether we communication good news or bad news.

iv) Nonverbal communication is also a part of verbal communication.

c) Comment to establish the truth of the following statements:

i) “Long, involved sentences tend to be difficult to understand. Therefore, the shorter the sentence, the better.”

ii) “Action speaks louder than words.”

d) Explain the utility of teleconferencing and videoconferencing. As a business tool, which may be considered as more effective.

e) Highlight the importance of interpersonal communication.

f) Name six golden rules for conducting an effective meeting.

g) Explain the components of virtual office and give two examples for the same.

(7×4)

2.

a) Suggest, what steps one should take in order to improve upon one’s listening?

b) “Good communication makes a mahanagar more efficient and effective in achieving organizational goals.” Critically examine the statement.

c) Do you agree with the statement that – ‘Silence is also sometimes a good means of communication.’

(5+7+6)

3.

a) Explain, how graphs, charts and other graphics in a written report make the report more effective in communicating desired messages and information.

b) ‘A memo is in nature of a letter and is yet not a letter.’ Discuss.

c) Explain in most cases what make us a poor communicator.

(6+6+6)

4.

a) Assume that in your company, the rate of dearness allowance has increased from 25% to 30% of basic pay of employees. As a head of the Establishment Section, write a circular for the company’s employees informing about such an increase in dearness allowance.

b) Due to some urgent personal work, you are supposed to go out of city and it is likely that you will not join office for the next 4 days. Write down an e-mail, which you would like to send to your boss informing about your absence from office and the fact that you will be out of city.

(9+9)

5.

a) You know that ‘an effective representation before the management improves the chances of promotion in an organization’. Therefore, you are very particular about ensuring effective representation. Suppose that you have to make a presentation to the management next week regarding the activities of your department, suggest how you will plan about it and what steps you would like to follow in order to make your presentation very effective.

b) State any five points which one should always remember to make one’s resume.

c) What are the difference between curriculum vitae (CV) and a resume?

(10+5+3)

6.

a) ‘A good leader is responsible for ensuring an effective communication within a group.’ In the light of this statement, discuss how a leader can ensure an effective system of communication among the group members.

b) ‘The emergence of information technology has revolutionized the ways by which people communicate in organizations and one of the ways is – paperless communication.’ Discuss and give examples how the emergence of information technology has made paperless communication more prevalent and cost-effective mode of communication in organizations.

(8+10)

7.

a) One of the responsibilities of an interviewer is to put the interviewee at ease. Assume that you are an interviewer. Suggest any two ways through you will put the interviewee at ease.

b) Name any two software, which you think will be of utmost use in making your annual report an effective one.

c) Write short notes on any three of the following:

i) Communication Styles

ii) Performance Appraisal Interview

iii) Characteristics of a good negotiator

iv) Body Language and its significance

(4+2+[3x4])

B4.5-R3: INTERNET TECHNOLOGIES & TOOLS Jan 2006

1.
a)	What is TCP/IP? Discuss the layers of TCP/IP.
b)	What is IP Host address? Discuss in detail.
c)	What is virtual reality? Describe its applications.
d)	What is a Proxy Server? What are its functions?
e)	What is file compression? How is it achieved?
f)	What is Domain Name System? Explain.
g)	What are digital certificates? Explain their role in Internet Security.
	(7×4)
2.
a)	What is Internet? Describe the Architecture of Internet. Explain how a router works.
b)	What are Cookies? How are they different from Microsoft Passports?
c)	What is email Spam? Explain, how, it can be blocked?
	(6+6+6)
3.
a)	What is Client/Server architecture? Explain the advantages and disadvantages of two-tier and three-tier architecture in detail.
b)	What is multimedia? What are the requirements for multimedia? Explain standardized data formats for Multimedia-based programming.
	(9+9)
4.
a)	What are Firewalls? How do they work?
b)	What are Viruses? What are the different types of viruses? Explain, how viruses work on Internet?
c)	Write short notes on: i) Smurf Attacks ii) CGI Scripts
	([2+2]+[2+2+4]+[3+3])
5.
a)	Explain briefly, the new features in IPv6 as compared to IPv4.
b)	Explain briefly, how IPv6 handles multiple headers? What is the purpose of multiple headers? Explain IPv6 addressing.
	(6+[4+4+4])

6.
a)	Explain, how graphic images are embedded in a web page?
b)	Explain the browser architecture.
c)	Explain caching in web browsers.
d)	What is Telnet?
	(4+5+5+4)
7.
a)	What are the different aspects of Network Security? What do you mean by Accountability and Authorization?
b)	Discuss the following techniques to ensure the data against accidental damage: i) parity bits ii) checksum iii) Cyclic redundancy Checks
c)	What is Internet Multicast Protocol? Explain Internet Group Management Protocol.
	(6+6+6)

B4.4-R3: COMPUTER GRAPHICS & MULTIMEDIA SYSTEM Jan 2006

1.

a) Discuss the merits and demerits of various clipping algorithms.

b) How does the Z buffer algorithm determines which surfaces are hidden?

c) Explain the Sutherland Cohen line-clipping algorithm. Is this applicable to any type of window? Justify your answer.

d) Explain how MIDI files are created and what are their applications in multimedia applications.

e) Describe briefly the Phong shading and compare it with Gouraud shading.

f) Explain the importance of vanishing point. What type of projection is associated with it? Explain that projection.

g) Describe the importance of compression in multimedia system. Compare and contrast JPEG and MPEG techniques.

(7×4)

2.

a) Differentiate between video compression standards and multimedia video compression standards.

b) What are the components of multimedia systems? Explain in brief each component.

c) Describe the functions of flat panel displays.

(4+10+4)

3.

a) Show that n^th degree B-spline basis function B_i,n (x) = 0, if x < t₁ or x > t_i+n-i.

b) A triangle having vertices at (0,0), (1,1) and (5,2) is rotated by 45 degree clockwise i) about origin and ii) about P(-1, -1) point. Obtain the coordinates of the vertices of the triangle using homogenous coordinate system.

c) What are the advantages of parametric representation of curves and surfaces in computer graphics?

(6+10+2)

4.

a) Describe different models used for illumination. How do you define surface normal vector? Explain its importance.

b) Explain ray tracing and compare it with ray casting. Describe the intersection of an arbitrary ray with yz plane.

c) Explain rendering. What are the approaches used for volume rendering? What are the steps used in the process of smooth shading?

(6+6+6)

5.

a) Explain why RGB color model is used for display. How different shades of colors are generated on the RGB monitors.

b) How is clipping done in three-dimensional domain? Discuss the various options for selecting different types of view volumes.

c) Describe Painter’s algorithm. Give its relative advantages and disadvantages over other methods.

(6+6+6)

6.

a) In a 3D coordinate system the plane XY(z = 0) represents the screen of monitor. A box is placed at the origin such that its three edges are touching x, y and z axes. Describe the transformation matrix needed to show the side view of the box on the screen.

b) What did you understand by morphing? Explain with the help of practical application.

c) Write a routing to design a two dimensional cubic Bezier curve shapes having first order continuity. Use interactive technique for selecting control points in XY plane for each section of curve.

(6+6+6)

7.

a) Explain where and why the magnetic storage is used in multimedia system?

b) Describe the operation of scanner. What criteria would you use for selecting scanner?

c) What are the main design issues for the multimedia authoring system? Briefly explain each one of these issues.

(4+4+10)

Jan 2006 B4.3-R3: SOFTWARE TESTING AND QUALITY MANAGEMENT

1. State whether the following statements are TRUE or FALSE. In each case, justify your answer using one or two sentences. Irrelevant and unnecessarily long answers will be penalized.

a) The terms software verification and software validation are essentially synonyms.

b) Introduction of additional sequence type of statements in a program can not increase its cyclomatic complexity.

c) Code walkthrough for a module is normally carried out after completion of unit test.

d) During code review you detect errors whereas during code testing you detect failures.

e) Branch coverage is a stronger testing technique compared to statement coverage technique.

f) Modern quality assurance paradigms are centered around to carryout thorough product testing.

g) A satisfactory way to test object-oriented programs is to test all the methods supported by the different classes individually and then by performing adequate integration and system testing.

(7×4)

2.

a) Explain why testing techniques used for traditional procedure-oriented programs can not effectively be used to test object-oriented programs? What additional types of tests are needed for object-oriented programs?

b) Explain the difference between code inspection and code walk through. Why is detection and correction of errors during inspection and walkthrough preferable to that achieved using testing?

c) Prepare a checklist that can be used for inspection of the user interface of a software product.

(6+6+6)

3.

a) What is the difference between the top-down and the bottom-up integration testing approaches? Explain your answer using an example. Why is the mixed integration testing approach preferred by many testers?

b) Design the black-box test suite for a program that accepts two strings and checks if the first string is a substring of the second string and displays the number of times the first string occurs in the second string.

c) Explain what do you understand by client-server software. What are its advantages over the traditional software architecture? How can a client-server software be effectively tested?

(6+6+6)

4. Consider the following program segement.

/* num is the number the function searches in a presorted integer array arr */

int bin_search(int num)

{

int min,max;

min =0;

max =100;

while(min!=max){

if(arr[(min+max)/2]>num)

max=(min+max)/2;

else if(arr[(min+max)/2]<num)

min=(min+max)/2;

else return((min+max)/2);

}

return(-1);

}

a) Draw the control flow graph for this program segment.

b) Determine the cyclomatic complexity for this program. (Show the intermediate steps in your computation. Writing only the final result is not sufficient)

c) How is the cyclomatic complexity metric useful?

(6+6+6)

5.

a) Explain, why measurement of software reliability is a much harder problem than the measurement of hardware reliability.

b) What do you understand by a reliability growth model? How is reliability growth modelling useful? Give examples of two reliability growth models.

c) Explain the importance of software configuration management in modern quality paradigms such as SEI CMM and ISO 9001. What problems might arise if a development organization does not use any configuration management tool?

(6+6+6)

6.

a) Explain two test coverage metrics for procedural code. How are these useful? Can these be used satisfactorily for object-oriented programs? Explain your answer.

b) Why effective testing of real-time and embedded systems is considered more difficult than testing traditional systems? Explain a satisfactory scheme to test real-time and embedded systems.

c) Distinguish between the static and dynamic analysis of a program. Explain at least one metric that a static analysis tool reports and one metric that a dynamic analysis tool reports. How are these metrics useful?

(6+6+6)

7.

a) What do you understand by volume testing? Explain using a suitable example how volume test cases can be designed and the types of defects these tests can help to detect.

b) Explain at least one defect metric and how this metric can be collected. Also explain how defects can be effectively tracked for a software product.

c) What do you understand by data flow testing? How is data flow testing performed? Is it possible to design data flow test cases manually? Explain your answer.

(6+6+6)

Jan 2006 B4.2-R3: DISCRETE STRUCTURES

1.

a) Can a relation R in a set A be both symmetric and anti symmetric? Justify your answer.

b) Write the negation of the following by changing the quantifiers:

“Every complete bipartite graph is not planar.”

c) Prove absorption law in a Boolean algebra.

d) How many ways can one right and one left shoe be selected from 10 pairs of shoes without obtaining a pair?

e) What is the largest possible number of vertices in a graph with 35 edges and all vertices of degree at least 3?

f) Find a grammar to generate the set

{0^m1ⁿ | m and n are non negative integers}

g) Let (A,*) be an algebraic system, where * is a binary operation such that for any a and b in A

a*b = a

Show that this operation is associative.

(7×4)

2.

a) Suppose R is an arbitrary transitive and reflexive relation on a set A. Prove that the relation E defined by “x E y iff x R y and y R x” is an equivalence relation.

b) Prove or disprove the validity of the following argument:

i) Every living thing is a plant or animal.

ii) Ram’s dog is alive and is not a plant.

iii) All animals have heart.

iv) Hence Ram’s dog has a heart.

(9+9)

3.

a) Prove that if R is a partial ordering relation on a set S, then for n ³ 2,there can not be a sequence s₁, s₂, s₃,….s_n of distinct elements of S such that s₁ R s₂ R s₃…Rs_nRs_1.

b) Minimize following switching function

S_m(0, 2, 8, 12, 13 ).

c) Consider the group (Z₄, ): the integer modulo 4 group with respect to the operation : addition modulo 4. Does H={[0], [2]} form a subgroup of Z₄. If yes, is it a normal subgroup? Justify.

(6+6+6)

4.

a) Solve the following:

a_n = 2 a _n-1 +1

where

a₀ =0

a₁= 1

a₂ = 3.

b) Find a generating function to count the number of integral solutions of

e₁ + e₂+ e₃ = 10 if for each i, 0 £ e_i

(9+9)

5.

a) Show that complement of a regular set is a regular set.

b) Write a grammar/ regular expression for the language on the alphabet{0,1} having all the strings with different first and last symbols.

c) Find a deterministic finite state machine that recognizes the set:

L={0ⁱ10^j | i ≥ 1, j ≥ 1}

(6+6+6)

6.

a) Apply Dijkstra’s algorithm to determine a shortest path between a and z in the following graph:

b 3 e

2 2 5 1

a 1 z

c

4 2 7 3

d 4 f

The numbers associated with the edges are distances between vertices.

b) Obtain the principal conjunctive normal form and principal disjunctive normal form of the formula S given by

(ØP® R )L (Q« P)

c) State Pigeon hole principle. Show that in a sequence of n²+1 distinct integers, there is either an increasing subsequence of length_(n+1) or decreasing subsequence of length.

(6+6+6)

Jan2006 B4.1-R3: COMPUTER BASED STATISTICAL AND NUMERICAL TECHNIQUES

1.

a) Compute

using Simpson’s rule of integration with h=0.2.

b) Let f(x) = ln x . Given the table of values

x:	0.40	0.50	0.70	0.80
In x:	-0.916291	-0.693147	-0.356875	-0.223144

Estimate the value of ln (0.60).

c) An infinite sequence of independent trials is to be performed. Each trial results in a success with probability p and a failure with probability 1 – p. What is the probability that

i) at least 1 success occurs in the first n trials;

ii) exactly k successes occur in the first n trials;

iii) all trials result in successes?

d) Suppose that the joint density of X and Y is given by

exp[-(x+y)] , 0≤x,y<¥

f(x,y)=

0 , otherwise

Find E[X] and P(Y>1).

e) The average working-set size X of a program is normally distributed with unknown mean m and a known variance s ² = 81. The program was executed 36 times and the average working-set size for each run recorded. The sample mean was computed to be 100 page frames. Assuming successive runs of the program are independent, find the 95 percent confidence interval for the mean average working-set size.

f) Write down probability density functions of

i) Uniform Variate

ii) Exponential Variate

iii) Normal Variate

iv) Gamma Variate

g) State the axioms of probability. Using these axioms, show that P(A)≤P(B) if A Í B.

(7×4)

2.

a) Consider the set of equations:

6 x + 2 y - z = 4

x + 5 y + z = 3

2x + y + 4 z = 27

Determine approximate solution of the system of equations using Gauss-Seidel method taking the initial solution as x=y=z=1.

b) For the data given below, write the Newton interpolating polynomial of degree 3 for f(x) = x² e^-x/2.

x:	1.10	2.00	3.50	5.00	7.10
f(x):	0.6981	1.4715	2.1287	2.0521	1.4480

Hence, find the error of the interpolate for x=1.75. (Given the tabulated value f(1.75) = 1.28611)

(9+9)

3.

a) In answering a question on a multiple choice test, an examinee either knows the answer or he guesses or he copies. Suppose each question has four choices. Let the probability that examinee copies the answer is 1/6 and the probability that he guesses is 1/3. The probability that his answer is correct given that he copied the answer is 1/8. Suppose an examinee answers a question correctly, what is the probability that he really knows the answer?

b) If X and Y are independent Poisson random variables with respective parameters l₁ and l₂, calculate

P(X=k | X+Y=n).

(8+10)

4.

a) The chances of three persons Mr. X, Y and Z becoming managers of a company are 4:2:3. The probabilities that bonus scheme shall be introduced if X, Y and Z become managers are 0.3, 0.5, 0.8 respectively. Find the probability that the bonus scheme will be introduced. What is the probability that X is appointed as the manager?

b) State central limit theorem. Using this theorem argue that if X is binomially distributed with parameters n and p, the distribution of approaches as standard normal Variate as n ® ¥.

c) If and are the standard deviations of independent random samples of size n₁=61 and n₂=31 from normal populations with =12 and =18, find .

(6+6+6)

5.

a) Let X_i, i=1,…,10 , be independent random variables, each uniformly distributed over (0, 1). Calculate an approximation to P( Σ X_i > 6).

b) Ifis a random sample from a Normal population with mean and variance unity, then show that is an unbiased estimator of.

c) X is Poisson Variate with parameters l. Obtain its Mgf. Hence find E[2X+3].

(6+6+6)

6.

a) Let X denote the main memory requirement of a job as a fraction of the total user-allocatable main memory of a computing center. The density function of X has the form:

k + 1) x^k ,if 0 < x < 1, k > 0,

f(x) = 0 , otherwise

A large value of k implies a preponderance of large jobs. If k =0, the distribution-of-memory requirement is uniform. Suppose you have a sample of size 8 given by:

0.25, 0.45, 0.55, 0.75, 0.85, 0.85, 0.95, 0.90

Estimate the value of k, using the method of moments.

b) It is suspected that the number of errors discovered in a system program is Poisson distributed. The number of errors discovered in each one-week period is given as follows:

Number of errors in one-week period (i)	Number of one-week period with i errors	Poisson probabilities	Expected frequencies
0	14	0.150	7.50
1	11	0.284	14.20
2	9	0.270	13.50
3	6	0.171	8.55
4	5	0.081	4.05
5+	5	0.044	2.20

Assume that the total number of errors observed in the 50 weeks was 95. Estimate the rate parameter λ for the Poisson probabilities given above. Test the hypothesis that errors occur according to Poisson distribution using significance level of 0.05.

(8+10)

7.

a) Find the coefficient of linear correlation between the variables X and Y given in the table.

X	1	3	4	6	8	9	11	14
Y	1	2	4	4	5	7	8	9

Also obtain the regression equation of Y on X for the data.

b) State the principle of least squares.

c) Show that cov(aX,Y) = a cov(X,Y).

(10+4+4)

Jan 2006 B3.5-R3: NETWORKING AND MOBILE COMMUNICATIONS

1.

a) How do the layers of the TCP/IP protocol suite correlate to the layers of the OSI?

b) Compare the performance of slotted aloha with that of pure aloha. What is the limitation of aloha protocol in general?

c) Explain the concepts of handoff and dropped call rate. What are soft and hard handoffs.

d) Draw and discuss the conceptual model of DECT (Digital European Cordless Telephone). Give its application areas.

e) If 20 MHz of total spectrum is allocated for a duplex wireless cellular system, with Simplex channel has 25KHz RF bandwidth, find the number of duplex channels and number of channels per cell site, if N=12 cell reuse is used.

f) Compare and contrast the various 2.5G technology paths that each of the major 2G standards provide. Which path has the highest Internet access speed?

g) Draw and explain the wireless LAN architecture and also explain the terms infrastructure mode and Adhoc mode.

(7×4)

2.

a) What are connection oriented and connectionless services? What are service primitives? Explain with an example how these are used.

b) Discuss the role of transport layer and data link layer in the OSI model.

c) What is spread spectrum communication. Explain the terms processing gain, pseudo random code generator and Walsch code.

(6+6+6)

3.

a) What are mobile data communication services and name them. Describe the architecture of HSCSD (High Speed Circuit Switched Data).

b) Draw the detailed block diagram of a cellular system and explain. Also explain the different strategies implemented to avoid interferences in TDMA, FDMA & CDMA systems.

(9+9)

4.

a) Give an account of radio specifications for cordless telecommunication systems such as CT 2 and DECT.

b) What is VSAT? Give the components of VSAT systems.

c) Draw and explain the functional architecture for PACS (Personal Access Communications System). Discuss the frame structure and its radio aspects.

(6+4+8)

5.

a) Draw CDMA based mobile system architecture and explain, how it provides reliable basic phone services. Write the benefits of CDMA to users.

b) Draw the basic reference architecture and signaling interfaces for GSM. Why is Smart card needed in GSM, while it is not required in AMPS?

(9+9)

6.

a) How do you compare D-AMPS and GSM systems in terms of coverage area, transmitted power and error control system, explain what you can do to address adjacent channel and co-channel interference.

b) With the help of a neat diagram explain the UMTS (Universal Mobile Telecommunication System) network architecture. Discuss in detail the logical parts: i) user equipment and ii) core network. How is the number of handoffs reduced for the fast moving traffic?

(9+9)

7.

a) Draw and explain the WAP network configuration. Also discuss the WAP protocol stack.

b) What is frequency management? Discuss different fixed channel assignment strategies. What are its limitations are compared to non-fixed channel assignment methods.

(9+9)

B3.4-R3: OPERATING SYSTEMS

1.

a) Does a process incur more execution overhead compared to a thread? Justify your answer.

b) Distinguish between multiprocessing and multiprogramming.

c) What are the “special files” in Unix?

d) What is the main difference between worm and virus?

e) State the practical limitations of implementing non-preemptive SJF algorithm.

f) What is the difference between a long-term scheduler and a short-term scheduler?

g) How can a single copy of a text editor be used to serve multiple users in a time-sharing system?

(7×4)

2.

a) What is TLB? Find out the effective memory-access time with an 80% hit ratio and the following access times:

TLB access time: 20ns; MM access time: 100ns

b) Describe the public-key encryption scheme and mention how is it advantageous to the data-encryption standard.

(8+10)

3. Consider the following page reference during a given time interval for a memory consisting of 5 frames: y,c,z,c,d,a,y,a,e,a,y,f,d,e. Using the i) FIFO replacement strategy and ii) the LRU replacement strategy compare the results. Repeat both FIFO and LRU replacement strategies for memory with 3 frames and same page reference pattern. Comment on the findings and draw a conclusion justifying the adoption of a particular replacement strategy.

(18)

4.

a) What does ‘init’ do? What happens to the parent process id of a child when the parent terminates before its child? When does a child become ‘zombie’?

b) With reference to Unix when do the following situations occur?

i) Single process table entry contains pointers to the same file table entry.

ii) Different file table entries point to the same i-node table entry.

iii) Shell ‘forks’ a copy of itself and ‘waits’ for the child to terminate.

c) How does CPU time-slice affect the Round-Robin algorithm?

(8+6+4)

5.

a) Show and explain an implementation of the classical producer-consumer (producer produces an item, keeps it in a buffer from where the consumer is picking it up) problem using semaphore.

b) What is dynamic loading? Mention its advantage. How is dynamic linking performed? Mention any disadvantage that you can think of for both the schemes.

(10+8)

6.

a) What is meant by a domain and the rights on it? Describe a Capability list and ways of protecting it from user tampering.

b) Rewrite the following code introducing code parallelism wherever applicable:

For i = 1 to k

a(i) = b(i) + c(i)

For j = 1 to k

d(j) = x(j) – y(j)

For p = 1 to k

x(p) = y(p) + b(p)

read(m,n,o,r)

q = m*n + r/o

write(q)

c) Using preemptive SJF(shortest-job-first) algorithm draw the Gannt chart and calculate the average waiting time for the following processes:

Process Arrival time Burst time

P₀ 0 6

P₁ 2 4

P₂ 3 10

P₃ 7 9

(9+4+5)

7.

a) Where and how “bit vector/table” is used? What are the advantages and disadvantages of the technique?

b) What is deadlock? How can deadlock be prevented by not allowing “Hold and Wait” ? Is it a feasible policy?

c) How can synchronization be achieved when two processes communicate by message passing?

d) Provide a programming example of multithreading giving improved performance over a single-threaded solution.

(5+5+5+3)