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MC1633 MOBILE COMPUTING

QUESTION BANK

Two Marks Questions:1. Define the relation between the data rate and bandwidth. What has harmonics to do with

bandwidth?2. Define channel capacity in terms of Nyquist a criteria and Shannon’s formula.3. Define an equation for free space loss in terms of db.4. What is ISI?5. List the parameters of GSM and IS – 95 system.6. What do you understand by co channel interference and adjacent channel interference.7. What factors influence the choice of digital modulation technique8. What is soft and hard handoff?9. What is meant by Coherent Bandwidth10. What is meant by Coherent Time.11. List and briefly describe different Media Access Mechanisms of Mobile Systems. 12. Describe the services provided by GSM network.13. What is authentication and how it is carried out.

Four marks questions:1. If the spectrum of the channel is between 3 MHz and 4MHz and SNR in db = 24 db, then find

the channel capacity using Shannon’s formula and based on Nyquist formula how many signaling levels are required to have to reach the given channel capacity.?

2. List modulation technique that are synchronous and asynchronous? Briefly explain variants of Phase Shift Keying with suitable diagrams

3. Given a channel with an intended capacity of 20 Mbps, the bandwidth of the channel is 3 MHz. What signal to noise ratio is required to achieve this capacity?

4. What is Eb / No ? How it is related to BER (Bit Error Rate)

5. Briefly describe multi path propagation mechanism in mobile communication. What are its effects

6. Given a channel with an intended capacity of 20 Mbps, the bandwidth of the channel is 3 MHz. What is the signal to noise required to achieve this capacity?

7. Briefly explain the concept of spread spectrum with a neat diagram. How spread spectrum overcomes narrowband interference?

8. What is near and far field effect?9. What are hidden and exposed terminals? What is CSMA/CA? How does prevent collision?

What are its draw backs?10. List and explain various mobile services of GSM?11. What are Traffic channel and control channel?12. Define the following:

a. MSISDNb. IMSIc. TMSId. MSRN

13.How authentication is carried out in GSM?

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14. How privacy is provided inGSM?

Eight Marks questions:1. What is channel capacity? How Nyquist and Shannon relate the channel capacity with

bandwidth and hence with bit rate? How multiplexing is important in communication? List and briefly explain different types of multiplexing mechanism giving there advantages and disadvantages.

2. Suppose a transmitter produces 50 watts of power.

a. Express the transmitter in units of dbm and dbw.b. If the transmitter’s power is applied to a un ity gain antenna with a 900 MHz carrier

frequency, what is the received power in dbm at a free space distance of 100 m.c. Repeat (b) for a distance of 10 km.d. Repeat (c) but assume a receiver antenna gain of 2.

3. What is fading? What are its classifications? Briefly describe them all by bringing out their salient feature.

4. Briefly describe FHSS and DSSS with neat diagrams.5. Draw and describe the system architecture of GSM System.6. What is radio interface? How it is made up of in GSM?7. List and discuss various control channels in GSM8. Draw and describe protocol architecture of GSM9. How localization of a subscriber is carried out in GSM10. What is ‘handover’ in mobile system? How it is effected in GSM?

Twelve Marks questions: 1. Briefly describe DAMA, PRMA, MACA, CDMA2. Explain the term interference in the space, time, frequency and code domain. What are the

countermeasures in SDMA, TDMA,FDMA and CDMA systems?3. How security is provided in GSM for the subscribers?

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