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Department of ECE Mobile And Wireless Communication

Dr. NAVALAR NEDUNCHEZHIYAN COLLEGE OF

ENGINEERING

Tholudur, Cuddalore (Dt) – 606 303.

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

QUESTION BANK

Subject Code/Subject: EC1451/MOBILE AND WIRELESS COMMUNICATION

Name : K.ANBUARASAN Designation : ASSISTANT PROFESSOR

Dept : ECE Semester : VIII

UNIT I

PRINCIPLES OF WIRELESS COMMUNICATION

Digital modulation techniques – Linear modulation techniques – Spread spectrum modulation –

Performance of modulation – Multiple access techniques – TDMA – FDMA – CDMA – SDMA

– Overview of cellular networks – Cellular concept – Handoff strategies – Path loss – Fading and

Doppler effect.

PART-A (1 MARK)

1. An AM signal is represented by x(t) = (20+4sin500πt)cos(2πx105t)V. The modulation index is

(A) 20 (B) 4

(C) 0.2 (D) 10

2. An AM signal is represented by x(t) = (20+4sin500πt)cos(2πx105t)V. The total signal power is

(A) 208 W (B) 204 W

(C) 408 W (D) 416 W

3. An AM signal is represented by x(t) = (20+4sin500πt)cos(2πx105t)V. The total sideband power is

(A) 4 W (B) 8 W

(C) 16 W (D) 2 W

4. A 2 kW carrier is to be modulated to a 90% level. The total transmitted power would be

(A) 3.62 kW (B) 2.81 kW

(C) 1.4 kW (D) None of the above

5. An AM broadcast station operates at its maximum allowed total output of 50 kW with 80% modulation.

The power in the intelligence part is

(A) 12.12 kW (B) 31.12 kW

(C) 6.42 kW (D) None of the above

6. A 2 MHz carrier is amplitude modulated by a 500Hz modulating signal to a depth of 70%. If the

unmodulated carrier power is 2 kW, the power of the modulated signal is

(A) 2.23 kW (B) 2.36 kW

(C) 1.18 kW (D) 1.26 kW

7. In a DSB-SC system with 100% modulation, the power saving is

(A) 50% (B) 66%

(C) 75% (D) 100%


8. In amplitude modulation, the modulation envelope has a peak value which is double the unmodulated

carrier value. What is the value of the modulation index?

(A) 25% (B) 50%

(C) 75% (D) 100%

9. If the modulation index of an AM wave is changed from 0 to 1, the transmitted power

(A) increases by 50% (B) increases by 75%

(C) increases by 100% (D) remains unaffected

10. A diode detector has a load of 1kΩ shunted by a 10000 pF capacitor. The diode has a forward

resistanceof 1Ω. The maximum permissible depth of modulation, so as to avoid diagonal clipping, with

modulating signal frequency of 10 kHz will be

(A) 0.847 (B) 0.628

(C) 0.734 (D) None of the above

11. An AM signal is detected using an envelope detector. The carrier frequency and modulating signal

frequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope

detector is.

(A) 500 μ sec (B) 20 μ sec

(C) 0.2 μ sec (D) 1 μ sec

12. For an AM signal, the bandwidth is 10 kHz and the highest frequency component present is 705 kHz.

The carrier frequency used for this AM signal is

(A) 695 kHz (B) 700 kHz

(C) 705 kHz (D) 710 kHz

13. In a broadcast transmitter, the RF output is represented as e(t) =

50[1+0.89cos5000t+0.30sin9000t]cos(6x106t)V. What are the sidebands of the signals in radians?

(A) 5x103 and 9x103 (B) 5.991x106, 5.995x106, 6.005x106 and 6.009x106

(C) 4x103, 1.4x104 (D) 1x106, 1.1x107, 3x106 and 1.5x107

14. An AM modulator has output x(t) = 40cos400πt + 4cos360πt + 4cos440πt. The modulation efficiency is

(A) 0.01 (B) 0.02

(C) 0.03 (D) 0.04

15. An AM modulator has output x(t) = Acos400πt + Bcos380πt + Bcos420πt. The carrier power is 100 W

and the efficiency is 40%. The value of A and B are

(A) 14.14, 8.16 (B) 50, 10

(C) 22.36, 13.46 (D) None of the above

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

C B A B A A B D A A B B B B A

PART-B (2 MARKS)

16. What is digital modulation?

A method of decoding information for transmission. Information, or in this case, a voice conversation is

turned into a series of digital bits; the 0s and 1s of computer binary language. At the receiving end, the

information is reconverted.

17. what is FSK, PSK, QAM?

The most fundamental digital modulation techniques are based on keying:

a)In the case of PSK (phase-shift keying), a finite number of phases are used.

b)In the case of FSK (frequency-shift keying), a finite number of frequencies are used.

c)In the case of ASK (amplitude-shift keying), a finite number of amplitudes are used.

d)In the case of QAM (quadrature amplitude modulation), a finite number of at least two phases, and at least two

amplitudes are used.


18. Define spread spectrum techniques

In spread spectrum, the signal occupies a bandwidth in excess of the minimum necessary to send the

information the band spread is accomplished by means of a code that is independent of the data, and a synchronized

reception with the code at the receiver is used for despreading and subsequent

19. Define FDMA?

Frequency Division Multiple Access", is the division of the frequency band allocated for wireless cellular

telephone communication into many channels, each of which can carry a voice conversation or, with digital service,

carry digital data. FDMA is a basic technology in the analog Advanced Mobile Phone Service (AMPS), the most

widely-installed cellular phone system installed in North America. With FDMA, each channel can be assigned to

only one user at a time. FDMA is also used in the Total Access Communication System (TACS).

20. Define TDMA

Time division multiple access (TDMA) is a channel access method for shared medium (usually radio)

networks. It allows several users to share the same frequency channel by dividing the signal into different timeslots.

The users transmit in rapid succession, one after the other, each using his own timeslot. This allows multiple stations

to share the same transmission medium (e.g. radio frequency channel) while using only the part of its bandwidth

they requir

21. What are the channels used in mobile communication systems?

Forward voice channels (FVC)

Reverse voice channels (RVC)

Forward control channels (FCC)

Reverse Control channels (RCC)

22. What are the basic units of a Cellular system?[MAY-2011]

Mobile stations

Base stations

Mobile Switching Center (MSC) or Mobile Telephone Switching Office (MTSO).

23. What are the classifications of Wireless technologies and systems?

Cellular mobile radio systems ,Cordless telephones ,Wide-area wireless data systems ,High-speed WLANs

,Paging/messaging systems and Satellite-based mobile systems

24. what is meant by handover technique.[MAY-2011]

In a cellular radio system having a two layer cell structure comprised by macro cells (1) overlaying

microcells (2), handover occurs only via the macro cell layer. Thus when the quality of a call handled by a microcell

(2) deteriorates below predetermined criteria the call is handed up rapidly to the umbrella macro cell and is only

handed back down to a microcell when the handset has been in that microcell for a predetermined time and the

quality of the link thereto exceeds predefined criteria.

25. What are the different types of Hand over?

Intra-satellite hand over

Inter-satellite hand over

Gateway hand over

Inter-system hand over

26. Define modulation.

It is the process of encoding information from a message source in a manner suitable for transmission.

27. State the different analog modulation schemes.

Amplitude and frequency modulation.

28. State the different modulation schemes.

Amplitude shift keying, frequency shift keying, phase shift keying.

29. Define amplitude modulation.


The amplitude of the high frequency carried is varied in accordance to the instantaneous amplitude of the

message signal.

30. State the techniques used for SSB generation.

Filter method and balanced modulator method.

31. State the advantages of digital modulation schemes.

Power efficiency and bandwidth efficiency.

32. Define bandwidth efficiency.

It describes the ability of the modulation scheme to accommodate data within a limited bandwidth.

33. Define Power efficiency.

It describes the ability of the modulation scheme to preserve the fidelity of the digital message at low power

levels.

34. State the different types of line coding.

Return to zero, non-return to zero and Manchester.

35. State the types of modulation schemes used in mobile communication.

GMSK, GFSK and DQPSK.

36. Give the equation used to represent a BPSK signal.

SBPSK (t) = m (t)

37. What is coherent detector?

If the receiver has prior knowledge of the transmitted signal then the receiver is known as coherent detector.

38. State the advantage of using GMSK rather than MSK.

The bandwidth occupied by GMSK modulated signal is less in comparison to MSK modulated signal.

39. What is CPFSK ?

Continuous phase frequency shift keying. It is another name for MSK.

40. What is QAM ?

Quadrature amplitude modulation.

41. State the difference between MSK and GMSK.

GMSK uses a Gaussian pulse shaping filter prior to MSK.

42. What is a diversity receiver?

Diversity receiver is the diversity scheme applied at the receiver end of the antenna in all effective technique

for reducing interference, where selective combiner is used to combine two-correlated signal.

43. Expand PCS, PLMR, NLOS and DECT.

PCS - Personal Communication Systems.

PLMR – Public Land Mobile Radio

NLOS – Non Line Of Sight

DECT – Digital Equipment Cordless Telephone

44. Mention the three partially separable effects of radio propagation.

The three partially separable effects of radio propagation are,

Multi path fading

Shadowing

Path loss

45. What is known as Quadrature Modulation?

In digital modulations, instead of transmitting one bit at a time, we transmit two or more bits simultaneously.

This is known as M-ary transmission. This type of transmission results reduced channel BW. However sometimes

the use two quadrature carriers for modulation. This process of transmitting 2 quadrature carrier for modulation is

known as quadrature modulation.

46. What are the design characteristics of digital modulation scheme?

Maximum data rate,

2 √ Eb cos (2πfct + θc)

Tb


Minimum transmitted power,

Maximum channel BW,

Maximum resistance to interfering signals,

Minimum circuit complexity.

47. What are coherent digital modulation techniques?

Coherent digital modulation techniques are those techniques which employ coherent detection. In coherent

detection, the local carrier generated at the receiver is phase locked with the carrier at the transmitter. Thus, the

detection is done by correlating received noisy signal and locally generated carrier. The coherent detections a

synchronous detection.

48. What are the non-coherent digital modulation techniques?

Non-coherent digital modulation techniques are those techniques in which the detection process does not

need receiver carrier to be phase locked with transmitter carrier. The advantage of such type of system is that the

system becomes simple. But the drawback of such a system is that the error probability increases.

49. Give some advantage of QPSK:

For the same bit error rate, the BKJ required by QPSK is reduced to half as compared to BPSK. Because of

reduced BW, the information transmission rate of QPSK is higher Carrier power almost remains constant.

50. Drawbacks of MSK as compared to QPSK:

1. The BW requirement of MSK is 1.5 fb, whereas it is fb in QPSK. Actually this cannot be said series

drawback of MSK. Because power to BW ratio of MSK is more 99% of signal.

2. Power can be transmitted within the BW of 1.2 fb in MSK. While QPSK needs around 8fb to transmit

the same power.

51. Bring out the difference between coherent and non-coherent binary modulation schemes

Coherent binary modulation Non-coherent binary modulation

Here the local carrier generated at the

receiver is phase locked with the carrier at the

transmitter. Thus detection is done by

correlating received noisy signal and locally

generated carrier.

The coherent detection is a synchronous

detection. Here the error probability does not

decreases

Here the detection process does not need

receiver carrier to be phase locked with

transmitter carrier.

Here error probability increases.

52. What is the error probability of MSK and DPSK?

The error probability of MSK is given by

No

EberfcPe

2

1

The error probability of DPSK is given by

No

EbPe exp

2

1

53.In minimum shift keying what is the relation between the signal frequencies and bit rate?

The bit rate is given by

No

EberfcPe

2

1

Where


Eb >>>>> Transmitted signal energy per bit;

No >>>>> Noise density

54. What is maximum likelihood decoder?

Set mkxf x / is always non-negative and since the logarithmic function is a monotonically increasing

function of its argument we may restate the decision rule in terms of metric as follows

Set ,imm

if mkXf x /ln is maximum for k = i

Where ‘ln’ denotes the a natural log. This decision rate is referred to as maximum likelihood rule and device

for its implementation is referred to as maximum likelihood decoder.

55.What is DPSK?

Differential phase –shift keying is the non-coherent version of PSK. It is differentially coherent modulation

method. It does not need a synchronous carrier at the demodulator. The input sequence of binary bits is modified

such that the next bit depends upon the previous bit. Therefore in the receiver bits are used ot detect the present

bit.

56.What are the advantages of DPSK?

DPSK does not need carrier at its receiver. This means that the complicated circuitry for generation of local

carrier is avoided.

The bandwidth requirement of DPSK is reduced compared to that of BPSK

57.What is capture effect?

The capture-effect is a direct result of the rapid nonlinear improvement in received quality for an increase

in the received power. If two signals in the same frequency band are available at an FM receiver, the one appearing

at the higher received signal level is accepted and demodulated, while the weaker one is rejected. This inherent

ability to pick-up the strongest signal and reject the rest makes FM systems very resistant to co-channel interference

and provides excellent subjective received quality. This effect is called as capture-effect.

PART-C (16 MARKS)

58. Describe in detail about the Analog Amplitude Modulation techniques used in mobile radio.

59. Describe in detail about the Angle Modulation techniques used in mobile radio.

60. Describe in detail about the demodulation techniques for FM waves used in mobile radio.

61. Describe in detail about the Digital modulation schemes BPSK. [MAY-2011]

62. Describe in detail about the Digital modulation schemes DPSK and QPSK.

63. Describe in detail about the Space diversity techniques.

64. Explain the concept of TDMA scheme. [MAY-2011]

65. Explain hand off process in cellular networks. [MAY-2011]


UNIT II WIRELESS PROTOCOLS

Issues and challenges of wireless networks – Location management – Resource management –

Routing – Power management – Security – Wireless media access techniques – ALOHA –

CSMA – Wireless LAN – MAN – IEEE 802.11 (a–b–e–f–g–h–i) – Bluetooth. Wireless routing

protocols – Mobile IP – IPv4 – IPv6 – Wireless TCP.Protocols for 3G & 4G cellular networks –

IMT – 2000 – UMTS – CDMA2000 –Mobility management and handover technologies – All-IP

based cellular network

PART-B (1 MARK)

PART-A (1 MARK)

66. To send a packet data using datagram, when a connection will be established

a) before data transmission

b) connection is not established before data transmission

c) no connection required

d) none of the above

67.connectivity is a concept related to

a) transmitting information,either by computer or by a phone

b) the interconnection within a computer

c)using computer networks to link people and resources

d)being in an active session with your computer

68.One of the most dramatic changes in connectivity and communications in the past five years or so has

been ____

a) mobile or wireless telephones b) public and private discussion

c) satellite uplinks d) running programs on remote computers

69.The four basic elements of any communication system include

a)peer-to-peer, videoconferencing, online photo-conferencing, net optical

b)sending and receiving devices, communication channel, connection device, and data transmission specifications

c)telephone lines, coaxial cables, fiber-optics cables, and communication channel

d)software, hardware, communication channel, network

70.These communication devices originate as well as accept messages in the form of data, information,

and/or instructions.

a) i-drives b)sending and receiving devices

c) key chain drives d) optical drives

71.The transmission medium that carries the message is referred to as the

a)send and receive device b)communication channel

c)protocol d)gateways

72.Data is transmitted using light through a ____ cable.

a)twisted pair b)fiber-optic

c)coaxial d)microwave

73.Which physical connection is the fastest?

a) twisted pair b) coaxial cable

c) fiber-optics d) microwaves

74.Most Web-enabled devices follow a standard known as


a)FireWire b)Bluetooth

c)TCP/IP d)Wi-FI

75.This wireless standard is widely used to connect computers to each other and to the Internet.

a) 802.11 b) RJ45 c)Blueband d) Broadband

76.Bluetooth is a type of radio wave information transmission system that is good for about

a)30 feet b)30 yards c) 30 miles d)300 miles

77.A term relating to sending data to a satellite is

a)uplink b) downlink c) modulate d)demodulate

78.A credit card-sized expansion board that is inserted into portable computers that connects the PC to the

telephone wall jack is called what?

a)Internal modem b)External modem c)PC Card modem d)Wireless modem

79.Standard telephone lines and conventional modems provide what is called

a)Bluetooth service b)dial-up service c)wireless service d)WiFI service

80.Special high-speed lines used by large corporations to support digital communications are known as

a)satellite/air connection service lines b)cable modems

c)digital subscriber lines d)T1, T2, T3 and T4 lines

81.The rules for exchanging data between computers are called

a)interconnections b)synchronous packages

c)protocols d)data transmission synchronization

82.Each computer on the Internet has a unique numeric address called a(n)

a)domain address b)protocol address

c)IP address d)Web address

83.____ is the process of breaking down information sent or transmitted across the Internet into small

parts called packets.

a)protocol b)bandwidth c)reformatting d)identification

84.Two or more computers connected so that they can communicate with each other and share information

is called a

a)satellite b)protocol c)broadcast d)network

ANSWER:

66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84

c c a b b b b c d a a a c b d c c c d

PART-B (2 MARKS)

85.Define routing. [MAY-2011]

Routing (or routeing) is the process of selecting paths in a network along which to send network traffic.

Routing is performed for many kinds of networks, including the telephone network, electronic data networks (such

as the Internet), and transportation networks

86. What is network security?

The field of networking, the specialist area of network security consists of the provisions made in an underlying

computer network infrastructure, policies adopted by the network administrator to protect the network and the

network-accessible resources from unauthorized access, and consistent

87. Define ALOHA


Aloha, also called the Aloha method, refers to a simple communications scheme in which each source

(transmitter) in a network sends data when ever there is a frame to send. If the frame successfully reaches the

destination (receiver), the next frame is sent. If the frame fails to be received at the destination, it is sent again. This

protocol was originally developed at the University of Hawaii for use with satellite communication systems in the

Pacific.

88. What is IMT 2000?

IMT 2000, also known as International Mobile Telecommunications 2000, is the ITU globally coordinated

definition of 3G covering key issues such as frequency spectrum use and technical standards. More information is

available in this presentation

89. What are different types of 3G Networks specified by IMT 2000?

ITU Recommendation ITU-R M.1457 specifies five types of 3G radio interfaces:

1.IMT-2000 CDMA Direct Spread, also known as UTRA FDD including WCDMA in Japan, ARIB / DoCoMo

recommendation. UMTS is developed by 3GPP.

2.IMT-2000 CDMA Multi-carrier, also known as Cdma2000 (3X) developed by 3GPP2. 3.IMT-2000 CDMA2000

includes 1X components, like cdma2000 1X EV-DO.

4.IMT-2000 CDMA TDD, also known as UTRA TDD and TD-SCDMA. TD-SCDMA is developed in China and

supported by TD-SCDMA Forum.

5.IMT-2000 TDMA Single Carrier, also known as UWC-136 (Edge) supported by UWCC.

6.IMT-2000 DECT supported by DECT Forum.

90. Define Home network

The home network of a mobile device is the network within which the device receives its identifying IP

address (home address).

91. Define Home address

The home address of a mobile device is the IP address assigned to the device within its home network.

92. What is Foreign network?

A foreign network is the network in which a mobile node is operating when away from its home network.

93. Define Care-of address

The care-of address of a mobile device is the network-native IP address of the device when operating in a

foreign network.

94. Define Home agent

A home agent is a router on a mobile node’s home network which tunnels datagrams for delivery to the

mobile node when it is away from home. It maintains current location (IP address) information for the mobile node.

It is used with one or more foreign agents.

95. Define foreign agent

A foreign agent is a router that stores information about mobile nodes visiting its network. Foreign agents

also advertise care-of-addresses which are used by Mobile IP.

PART-C (16 MARKS)

96. Explain ALOHA

97. In detail explain IEEE802.11[MAY-2011]

98. Explain in detail about 3G and 4G networks

99. Explain CDMA2000

100. Explain UMTS

101. Explain Mobility Management and Handover Technologies All Mobile Ip Networks [MAY-2011]

102. What is need for IPV6 protocol? Explain its advantages?

103.Explain about location management and resource management? [MAY-2011]


UNIT III

TYPES OF WIRELESS NETWORKS

Mobile networks – Ad-hoc networks – Ad-hoc routing – Sensor networks – Peer-Peer networks

– Mobile routing protocols – DSR – AODV – Reactive routing – Location aided routing –

Mobility models – Entity based – Group mobility – Random way – Point mobility model.

PART-A (1 MARK)

104.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)an increased; the same carrier frequency. b)a decreased; the same carrier frequency.

c)an increased; a different carrier frequency. d)a decreased; a different carrier frequency.

105.State the error control scheme used in Bluetooth.

a)Go-back-N. b)Selective repeat. c)Idle ARQ.

106.A wireless LAN found in a train or bus station is an example of a(n):

a)public wireless LAN.

b)infrastructure wireless LAN.

c)ad-hoc wireless LAN.

107.Which of the following statements is true of a wireless LAN?

a)Communication between devices may only occur via an access point.

b)Communication between devices may only occur in ad-hoc mode.

c)Communication between devices may occur via an access point, or in ad-hoc mode.

108.The operational modes of DCF used in IEEE 802.11 networks are:

a)CSMA/CA and RTS/CTS. b)Polling and CSMA/CA.

c)CSMA/CD and RTS/CTS. d)Polling and RTS/CTS.

109.GSM includes HLR and VLR databases. Their uses may be described as:

a)a VLR copies all relevant information for a user from the HLR every time a user moves from one cell to

another.

b)the contents of HLR's and VLR's is always the same.

c)every time a user moves into a location area of a different MSC, all relevant user information is copied from the

VLR to the HLR associated with the new MSC.

d)every time a user moves into the location area of a different MSC, all relevant user information is copied from

the HLR to the VLR associated with the new MSC.

110.Telephone systems may be classified as:

a)simplex and symmetrical. b)simplex and asymmetrical.

c)duplex and asymmetrical. d)duplex and symmetrical.

111.A network that provides a constant bandwidth for the complete duration of a message transfer is a:


a)packet switched network. b)cell switched network. c)circuit switched network.

112.A router:

a)forwards a packet to all outgoing links.

b)forwards a packet to all outgoing links, except the link upon which the packet originated.

c)determines on which outgoing link a packet is to be forwarded.

d)forwards a packet to the next free outgoing link.

113.The Internet is an example of a:

a)cell switched network. b)circuit switched network. c)packet switched network.

114.A data link between the head office of a financial organization and one of its branches runs

continuously at 2.048 Mbps. Between the hours of 0900 and 1700 it is noted that there are 295 bits received

in error. Determine the bit error rate.

a)5 x 10-9 b)2 x 10-7 c)5 x 10-8 d)2 x 10-10

115.The optical fibre trans-Atlantic cable TAT-14 includes a section from Bude, Cornwall to Tuckerton,

New Jersey. Determine the propagation delay if the route length is 6,254 km.

a)31.27 ms. b)31.98 ms. c)312.7 ms. d)3.198 ms.

116.A file is downloaded to a home computer using a 56 kbps modem connected to an Internet Service

Provider. If the download completes in 2 minutes, estimate the maximum size of data downloaded.

a)26.88 Mbit. b)13.44 Mbit. c)6.72 Mbit. d)336 Kbit.

117.Baseband transmission may be defined as the transmission of a signal over a link:

a)by means of wires. b)without any change in frequency.

c)which is relatively short. d)at a different band of frequencies.

118.Skin effect may be described as:

(Note: more than one answer is correct.)

a)conduction restricted to a small central region of a conductor.

b)conduction of electricity through skin.

c)conduction restricted to the outer layer of a conductor.

d)a thin layer of electricity.

ANSWER:

104 105 106 107 108 109 110 111 112 113 114 115 116 117 118

b c a c a D D c c c A a c b a

PART-B (2 MARKS)

119.Wireless ad hoc network

A wireless ad hoc network is a decentralized wireless network.[1] The network is ad hoc because it does

not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed

(infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes,

and so the determination of which nodes forward data is made dynamically based on the network connectivity.

120.Mobile ad hoc network

A mobile ad hoc network (MANET), sometimes called a mobile mesh network, is a self-configuring

network of mobile devices connected by wireless links

121. List of ad hoc routing protocols[MAY-2011]

An ad hoc routing protocol is a convention, or standard, that controls how nodes decide which way to route

packets between computing devices in a mobile ad hoc network

1 Pro-active (table-driven) routing

2 Reactive (on-demand) routing

3 Flow-oriented routing


4 Adaptive (situation-aware) routing

5 Hybrid (both pro-active and reactive) routing

6 Hierarchical routing protocols

7 Host Specific Routing protocols

8 Geographical routing protocols

9 Power-aware routing protocols

10 Multicast routing

11 Geographical multicast protocols (Geocasting)

122. Define P2P

P2P networking has generated tremendous interest worldwide among both Internet surfers and computer

networking professionals. P2P software systems like Kazaa and Napster rank amongst the most popular software

applications ever. Numerous businesses and Web sites have promoted "peer to peer" technology as the future of

Internet networking.

123.What Are P2P Software Applications?

A good definition of P2P software was proposed by Dave Winer of UserLand Software many years ago

when P2P was first becoming mainstream. Dave suggests that P2P software applications include these seven key

characteristics: the user interface runs outsides of a Web browser

computers in the system can act as both clients and servers

the software is easy to use and well-integrated

the application includes tools to support users wanting to create content or add functionality

the application makes connections with other users

the application does something new or exciting

the software supports "cross-network" protocols like SOAP or XML-RPC

the user interface runs outsides of a Web browser

computers in the system can act as both clients and servers

the software is easy to use and well-integrated

the application includes tools to support users wanting to create content or add functionality

the application makes connections with other users

the application does something new or exciting

124. Define mobility models[MAY-2011]

Mobility models represent the movement of mobile users, and how their location, velocity and acceleration

change over time. Such models are frequently used for simulation purposes when new communication or navigation

techniques are investigated. Mobility management schemes for mobile communication systems make use of

mobility models for predicting future user positions

125. Define Dynamic Source Routing

Dynamic Source Routing (DSR) is a routing protocol for wireless mesh networks. It is similar to AODV in

that it forms a route on-demand when a transmitting computer requests one. However, it uses source routing instead

of relying on the routing table at each intermediate device. Many successive refinements have been made to DSR,.

126. What is a diversity receiver?

Diversity receiver is the diversity scheme applied at the receiver end of the antenna in all effective

technique for reducing interference, where selective combiner is used to combine two-correlated signal.

127. Expand PCS, PLMR, NLOS and DECT.

PCS - Personal Communication Systems.

PLMR – Public Land Mobile Radio

NLOS – Non Line Of Sight

DECT – Digital Equipment Cordless Telephone


128. Mention the three partially separable effects of radio propagation.

The three partially separable effects of radio propagation are,

Multi path fading, Shadowing, Path loss

129. Mention the basic propagation mechanisms, which impact propagation in mobile communication.

The basic propagation mechanisms are,

Reflection Diffraction Scattering

130. What is reflection?

Reflection occurs when a propagating electromagnetic wave impinges upon an object, which has very

large dimension when compared to the wavelength of propagating wave.

131. What is diffraction?

Diffraction occurs when the radio path between the transmitter and receiver is

obstructed by a surface that has sharp irregularities.

132. What is scattering?

Scattering occurs when the medium through which the wave travels consists of objects with dimensions

that are small compared to the wavelength and where the number of obstacles per unit volume is large.

133. Define Brewster angle?

The Brewster angle is the angle at which no reflection occurs in the medium of origin. It occurs when the

incident angle b is such that the reflection coefficient Is equal to zero.

134. Why we use 1mi intercept for mobile communication?

Within a 1mi radius the antenna beam width of a high gain omni-directional

antenna is narrow in vertical plan. Larger the elevation angle weaker the reception level.

135. What are the possible conditions in a point-to-point prediction model? [MAY-2011]

The possible conditions in a point to point prediction model are,

Non Obstructive direct path.

Obstructive direct path.

136. What are the merits of point-to-point model?

The merits are,

Produces an accurate prediction with a deviation of 8dB.

Reduces the uncertainty range by including the detailed terrain contour information.

PART- C (16 MARKS)

137.Explain about wireless adhoc network[MAY-2011]

138.Explain about Mobile ad hoc network

139.Explain ad hoc routing protocols

140.Define mobility models and briefly explain them

141.Explain in detail about peer to peer networks

142.Explain about DSR[MAY-2011]

UNIT IV

ISSUES AND CHALLENGES

Issues and challenges of mobile networks – Security issues – Authentication in mobile

applications – Privacy issues – Power management – Energy awareness computing. Mobile IP

and Ad-hoc networks – VoIP applications.


143.A block of data consisting of 2048 bits is transmitted between two computers interconnected by 450 m

of twisted-pair wire. If the transmission rate is 34 kbps determine a, the ratio of propagation delay to

transmission delay.

a)376 x 10-6 b)3.76 x 10-6 c)3.76 x 10-3 d)37.6 x 10-6

144.Asynchronous transmission may be defined as:

a)communication where the receiver clock must be in approximate synchronism with that of the transmitter.

b)communication where the receiver clock must be in exact synchronism with that of the transmitter.

c)communication where receiver will operate satisfactorily, even if its clock frequency is appreciably different to

that of the transmitter.

145.Synchronous transmission may be defined as:

a)communication where the receiver will operate satisfactorily, even if its clock frequency is appreciably different

to that of the transmitter.

b)communication where the receiver clock is arranged to be in exact synchronism with that of the receiver.

c)communication where the receiver clock must be in approximate synchronism with that of the transmitter.

146.Manchester encoding is principally designed to:

a)ensure that a transition occurs in the centre of each bit period.

b)increase the bandwidth of a signal transmitted on the medium.

c)ensure that the line remains unbalanced.

d)have more than one symbol per bit period.

147.Which of the following correctly describes slot time?

a)The worst-case signal propagation delay time plus a safety margin.

b)Twice the worst-case signal propagation delay time.

c)Twice the worst-case signal propagation delay time plus a safety margin.

d)The collision window.

148.When a station detects that a collision has occurred it:

a)waits a random interval in time and then re-examines the medium to see if it is free.

b)waits a random interval in time and then retransmits.

c)waits until the medium becomes free and then retransmits.

149.An L DATA. request frame in the IEEE802.3 standard is:

a)a connectionless, acknowledgement.

b)a connectionless, unnumbered frame.

c)a connectionless, unnumbered acknowledgement.

150.Subrate multiplexing may be defined as:

a)a form of multiplexing that is adequate but incurs some loss of performance.

b)dividing a data channel into two, or more, lower rate data channels.

c)multiplexing a number of channels in such a way that the aggregate bandwith is less than the sum of the

bandwidths of each channel being multiplexed.

151.In relation to DES, chaining is used because:

a)chaining, in addition to secrecy, provides integrity of data.

b)in electronic code book mode of working one, or more, blocks of data may be tampered with in transmission

and the receiver be unaware of the fact.

c)encryption is achieved more rapidly.

d)a greater degree of secrecy is provided.

152.Select the answer/s that correctly apply to an RSA digital signature.

a)A digital signature proves to a recipient that the sender is authentic.

b)A digital signature facilitates non-repudiation.

c)A digital signature provides a message digest.


d)A digital signature ensures that a message is correctly encrypted.

143 144 145 146 147 148 149 150 151 152

d a b a C a b b a b

PART-B (2 MARKS)

153. What are main subsystems of GSM architecture?

i) Base station subsystem (BSS)

ii) Network &switching subsystem (NSS)

iii) Operation support subsystem (OSS)

154. What are frequencies used in forward and reverse link frequency in GSM?

(890-915) MHz- reverse link frequency, (935-960) MHz-forward link frequency

155. What is CDMA digital cellar standard (is 95)?

IS-95- interim standard

IS 95 allows each user with in the a cell to use the same radio channel and user in adjacent cell also use the same

radio channel since this is a direct sequence spread spectrum CDMA system.

156. What are frequencies used in forward and reverse link frequency in IS-95?

(824-849) MHz- reverse link frequency

(869-894) MHz-forward link frequency

157. State certain access technologies used in mobile satellite communication systems.

FDMA, TDMA and CDMA.

158. State the different types of handoffs.

Soft handoff, hard handoff, forced handoff, delayed handoff and mobile associated handoff.

159. What is intersystem handoff ?

During a course of a call, if a mobile moves from one cellular system to a different cellular system

controlled by a different MSC it is referred as intersystem handoff.

160. State the expression that relates co channel reuse ratio (Q) to radius (R) of a cell

Q = D/R

D – Distance between center of co channel cells

161. State the expression used to locate co channel cells.

N = i2 + ij + j2

162. Define the term dwell time.

The time over which a call may be maintained within a cell without handoff.

163. State the advantage of umbrella cell approach.

It provides large area coverage to high speed users while providing small area

coverage to users traveling at low speeds.

164. Define co channel cells.

The cells that operate with the same set of frequencies are referred as co channel cells.

165. Define the term Erlong.

One Erlong represents the amount of traffic intensity carried by a channel that is completely occupied.

PART-C (16 MARKS)

166.Explain power management

167.explain about computer security

168.Explain about Voice over IP[MAY-2011]

169.With suitable block diagram explain the GSM system?


170.Explain the concepts of CDMA. What are its merits and demerits? Explain the working principle of

RAKE receiver.

171.Explain the TDMA frame structure and derive the efficiency of a TDMA system

172.Explain detail about DECT?

173.Explain detail about IS-95

UNIT V

SIMULATION

Study of various network simulators (GloMoSim – NS2 – Opnet) – Designing and evaluating the

performance of various transport and routing protocols of mobile and wireless networks using

network simulator (any one).

PART-A (1 MARK)

174.Select the answer/s that correctly apply to PGP encryption.

a)RSA is used to encrypt the message to be transferred.

b)RSA is used to exchange a private key between sender and recipient.

c)Private key encryption is used to encrypt the message to be transferred.

d)RSA is used to encrypt a message digest.

175.Two security threats that E-commerce must guard against are that an eavesdropper may _____

Internet communication to obtain_____ information which may then be used by a third party to make

_____ purchases. Secondly, a bogus site may be used to obtain _____ without providing any goods or

services.

a)interrupt; some; fraudulent; money

b)intercept; confidential; multiple; details

c)intercept; confidential; fraudulent; money

d)intercept; some; free; money

176.Select which reasons Secure Electronic Transactions (SET) is preferred to SSL.

a)The vendor can verify that the purchaser has a legitimate card.

b)Guarantees delivery of goods or services.

c)The person making the payment is the legitimate cardholder.

d)The purchaser may verify that the vendor is authorized to engage in payment card transactions.

177.Network address translation is a technique whereby multiple hosts may be active, each assigned a ____

address. Every datagram passed to the Internet, via a NAT router, has its source address changed to a

single IP address assigned to the organization, irrespective of which host is active. For NAT to work, the

router holds a table which maps ____ to ____.

a)an IP; public addresses; private address and associated TCP port address

b)an IP; addresses; an Internet address

c)a unique private IP; private addresses; the Internet address and associated TCP port address

178.Loading the contents of routing tables into a router prior to it being put into service is an example of

which routing protocol?

a)Flooding. b)Link-state shortest-path-first.

C)Static. d)Distance vector.

179.Tunneling may be described as whereby a _______ receives a datagram, or packet, on an incoming

port and forwards it to an outgoing port _______.


a)router; using the same protocol

b)multiprotocol router; formatted with the same protocol

c)multiprotocol router; formatted with a different protocol

180.The address resolution protocol (ARP) is necessary in an IP network because:

a)when a datagram is passed to layer 2, a MAC layer frame is formed which must include the IP address of the

destination host to which the frame is to be sent. ARP is used to find the required IP address.

b)ARP is used to find the appropriate IP address, given a MAC address.

c)when a datagram is passed to layer 2, a MAC layer frame is formed which must include the layer 2 address of

the destination host to which the frame is to be sent. ARP is used to find the appropriate MAC address, based

upon the IP destination address contained within the datagram.

181..Which of the following definitions correctly describes the Dynamic Host Configuration Protocol

(DHCP)?

a)DHCP enables a NIC to determine the MAC address for a given IP address.

b)DHCP is a routing protocol run by routers within a network.

c)DHCP is a technique whereby IP addresses are assigned centrally by a server to each host.

d)DHCP enables a NIC to determine the IP address for a given MAC address.

182.A telephone customarily includes a 4-wire to 2-wire hybrid. The purpose of a hybrid is:

a)to merge/separate signals associated with the microphone and speaker.

b)to interconnect the 4 wires of a telephone to a line.

c)to combine the signals associated with the microphone and speaker.

183.The primary purpose of a Remote Concentrator Unit (RCU) is:

a)to aggregate small loads of traffic per line into a smaller number of correspondingly heavier loaded lines.

b)to provide economy through pair gain.

c)to reduce the number of subscriber cable pairs at a LE/CO.

d)to connect subscribers that are beyond the maximum allowable distance from the LE/CO.

184.A 2B1Q code offers the following advantage:

a)line signaling rate is half that of the data rate.

b)A strong clock component is embedded within the line signal.

c)A long period of constant voltage line state is avoided.

185.Modems use a training phase to:

a)configure them.

b)adjust the bit error rate.

c)determine the maximum available bit rate for communication.

d)determine the maximum possible bit rate for communication.

186.The Domain Name System (DNS) is primarily used to:

a)determine the symbolic name of a host, given its IP address.

b)determine the MAC address of a host, given its IP address.

c)remove the need for a user to indicate a host they wish to communicate with by means of an IP address

expressed in binary form.

d)determine the IP address of a host, given its MAC address.

187.Multipurpose Internet Mail Extension (MIME) was developed:

a)to support text-based email messages.

b)to support email messages containing text and video.

c)to support email messages containing audio and video.

d)to support email messages containing text, audio and video.

188.Two hosts, each located in a different network, exchange their emails via the Internet and make use of

a pair of email gateways. Such gateways are necessary because:



a)each host is using a different email application and email message format.

b)each host is using a different email message format.

c)each host is on a separate network.

d)each host is using a different email application.

189.TCP provides a reliable service which includes the use of sequence numbering. The sequence number

shown in a TCP header indicates:

a)the first byte being carried within a segment.

b)the last byte being carried within a segment.

c)the sequence number of the segment.

190.A reliable stream service in TCP is described as two-way transmission, free of transmission ____, with

no lost or duplicate ____, and the bytes are delivered in the same ____ in which they were transmitted.

a)errors; bytes; manner b)failure; packets; sequence

c)errors; bytes; sequence d)errors; activity; manner

191.Flow control is used in TCP for the following reason/s.


a)A sending host is able to transmit bytes at a faster rate than a receiving host is able to receive them.

b)A sending host transmits bytes at a slower rate than a host can receive them.

c)A sending host is able to transmit bytes at a faster rate than a receiving host is able to process them.

d)To ensure that a receiving host's buffer does not overflow.

192.Which of the following features are deployed when using TCP in cellular radio networks for efficient

operation?

a)Large MTU. b)Small window size. c)Go-Back-N ARQ protocol.

ANSWER:

174 175 176 177 178 179 180 181 182 183 184 185 186

D C a c c c C C a d a c c

187 188 189 190 191 192

D d a c d c

PART-B (2 MARKS)

193.What is CDPD?

CDPD is a Cellular packet digital Data System that uses packet switched data .The bit rate in the RF channel

for CDPD is !9.2kbps

194.Write some features of TDMA?

*In TDMA , no. of time slots depends upon modulation technique ,available bandwidth

*Data transmission occurs in bursts

*It uses different time slots for transmission and reception, then duplexers are not

required

195.Write some features of CDMA?

*In CDMA system, many users share the same frequency either TDD or FDD may be Used

*Channel data rate is high

*Multipath fading may be substantially reduced

*CDMA uses co –channel cells, it can use macroscopic spatial diversity to provide soft hand off

196.Write the features of DECT?

1.DECT provides a cordless communication framework for high traffic intensity, short range telecommunication

and covers a broad range of applications and environment


2.It supports telepoint services

3.It provides low power radio access between portable parts and fixed base station’s

at ranges of upto a few hundred meters

197.What are the interfaces used in the GSM?

GSM radio air interface, Abis interface, A interface

198.What are the types of services in GSM?

Tele services and Data services

199.Write some third generation wireless standards.

Personal communication system, IMT-2000 and UMTS

200.What is Bluetooth?

It is an open standard that provides an ad-hoc approach for enabling various devices to communicate with

one another within nominal 10 meter range. It operates in the 2.4 Ghz ISM band and uses frequency hopping TDD

scheme for each radio channel

201.What is the forward and reverse link frequency for AMPS?

(890-915) MHz- reverse link frequency

(935-960) MHz-forward link frequency

202.Write the specifications of DECT ?

Frequency band –1880-1900Mhz

No. of carriers - 10

RF channel bandwidth -1.728MHz

Multiplexing –FDMA/TDMA

Duplex-TDD

203.What is near-far effect in wireless network?

When used with FM or spread spectrum modulation, it is possible for the strongest user to successfully

capture the intended receiver , even when many users are also transmitting . If the closest transmitter is able to

capture a receiver because of small propagation path loss, it is called as near -far effect in wireless network

204. Write some standards used in 2G system

GSM, IS-136, IS-95,Pacific Digital Cellular standard

205. Define handoff ? [MAY-2011]

When a mobile moves from one cell to another the control of this mobile is transferred from one cell to

another. This process is referred as handoff.

PART-C (16MARKS)

206. Explain Glomosim [MAY-2011]

207. Explain NS2

208. Explain about OPNET

209. Compare NS2 with Glomosim [MAY-2011]

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