MobileComputing

SVKM’s NMIMSMukesh Patel School of Technology Management & Engineering

Programme : B.Tech (Comps) Year : 4th Sem : VIIIAcademic Year : 2014-15 Marks : 15 Faculty : Mudit KapoorDate : 10-Feb-2014 Duration : 45 mins Time : 1200 to 1245 hrsSubject : Mobile Computing Code : BTCO08003 Class Test 1 Set A

Instructions:

1. Answer three questions. Q1 is compulsory.2. Each question carries five (5) marks

Q1. Answer the following: (Marks 05, CO1)

i) ________ is a second-generation cellular phone system based on CDMA and DSSS.

A) GSM B) D-AMPS C) IS-95 D) none of the above

ii) Iridium satellites are ________satellites. (LEO)

iii) Which one of the following is not a step in process migration?

(a) Process is detached from its source node

(b) State is transferred and imported into a new instance on the remote node

(c) Migration request is issued to a source node

(d) Destination process instance is created

iv) Process’s address space is not included in the transferred state of a migrated process? (True/False)

v) The operational modes of DCF(Distributed Coordination Function) used in IEEE 802.11 networks are:

A) Polling and RTS/CTS. B) CSMA/CD and RTS/CTS

C) CSMA/CA and RTS/CTS. D) Polling and CSMA/CA.

Q2. Discuss about the short history of wireless communication? (Marks 05, CO2)

Q3. What are the possible attacks and protection methods on mobile agents? (Marks 05, CO3)

Q4. Explain in detail about the aglet? (Marks 05, CO3)

Event Model

Clone listener: Listens for cloning events. One can customize this listener to take specific actions when an aglet is about to be cloned, when the clone is actually created, and after the cloning has taken place.

Mobility listener: Listens for mobility events. One can use this listener to take action when an aglet is about to be dispatched to another context, when it is about to be retracted from a context, and when it actually arrives in a new context.

Persistence listener: Listens for persistence events. It allows the programmer to take action when an aglet is about to be deactivated and after it has been activated.

Application: Aglets have been applied in various scenarios, including e-commerce, the e-market place, air tickets and package tours.

Threats posed by mobile agentsDestruction ofdata, hardware, current environment

Denial of serviceblock executiontake up memory prevention of access to resources/network

Breach of privacy / theft of resourcesobtain/transmit privileged informationuse of covert channels

HarassmentDisplay of annoying/offensive informationscreen flicker

Repudiationability to deny an event / action ever happened

Aglets are a Java-based framework for mobile agents, designed by IBM. With aglets, one can construct objects that can move from one host on the network to another; that is, an aglet that executes on one host can suddenly halt execution, dispatch to a remote host and start executing again. When the aglet moves, it takes along its program code as well as the states of all the objects it is carrying. The aglet framework has been developed by the IBM Tokyo Research Laboratory, Japan.

SVKM’s NMIMSMukesh Patel School of Technology Management & Engineering

Programme : B.Tech (Comps) Year : 4th Sem : VIIIAcademic Year : 2014-15 Marks : 15 Faculty : Mudit KapoorDate : 10-Feb-2014 Duration : 45 mins Time : 1200 to 1245 hrsSubject : Mobile Computing Code : BTCO08003 Class Test 1 Set BInstructions:

1. Answer three questions.Q1 is compulsory.2. Each question carries five (5) marks

Q1. Answer the following: (Marks 05, CO1)

i) In the third generation of cellular phones, ______ uses a combination of W-CDMA and TDMA.

A) IMT-DS B) IMT-MC C) IMT-TC D) IMT-SC

ii) AMPS operates in the ISM _____ band. (800MHz)

iii) Which one of following is not an application of process migration?

(a) Parallelizable application

(b) Resource sharing application

(c) Migration-aware application

(d) Network and mobile computing application

iv) The centralised control mechanism used by Bluetooth is suitable for use in an ad-hoc wireless LAN because devices in ad-hoc networks communicate directly with each other.(True/False)

v) The performance of a scatternet degrades as the number of piconets is increased. Degradation is caused by _________ probability that two, or more, devices may simultaneously attempt transmission using ____________.

A) a decreased; a different carrier frequency.

B) an increased; the same carrier frequency.

C) a decreased; the same carrier frequency.

D) an increased; a different carrier frequency.

Q2. Explain hidden and exposed terminals? With diagram. (Marks 05, CO2)

Q3. Write down the steps involve in process migration? (Marks 05, CO3)

Q4. What are the characteristics of the Mobile agents? (Marks 05, CO3)

The steps in process migration1. A migration request is issued to a remote node.2. A process is detached from its source node 3. Communication is temporarily redirected4. The process state is extracted.5. A destination process instance is created6. The state is transferred and imported into a new instance7. Some means of forwarding references 8. The new instance is resumed

Bandwidth conservationReduction of latencyReduction of completion timeAsynchronous (disconnected) communicationsLoad balancingDynamic deployment