Model Answer of Mobile Communication

B. Tech. (6th Semester) Examination)

Paper Code: AR-9155

Branch: Information Technology

Time Allowed: 3hours Maximum Marks: 100

Part-A (All questions are compulsory)

Objective Type Questions (1*10=10Marks)

Q.1.Network Layer is responsible for ______packets through a network between two

entities over many other intermediate systems.

(a)Routing (b) signal detection (c) model (d) none of these.

Ans. Routing

Q.2.End –to-end connection is established in _____ Layer.

(a) Transport Layer (b) data link Layer(c) Application layer (d) none of these

Ans. Transport Layer

Q.3. International telecommunication Union (ITU) is located in ________.

(a) Poland (b) South Africa. (c) Finland (d) None of these.

Ans. None of these

Q.4. Point to point or point to multipoint connection is responsible for _____ Layer.

(a) Physical (b) Transport layer (c) Application (d) none of these.

Ans. None of these

Q.5.MEO satellite operates at the distance of about _______ Km.

(a) 5000-90000 (b) 5000- 12000 (c) 200-6000 (d) None of these.

Ans.5000-12000

Q.6. LEO satellites operates at the distance of about ____ Km.

(a) 500-1500 (b) 6000-70000 (c) 8000-9000 (d) none of these.

Ans.500-1500

Q.7. FIC (Fast information channel) contains __________ with 256 bits each.

(a) Fast information blocks (b) fast information beats (c) first information band (d) None

of these.

Ans. Fast Information Blocks

Q.8. The IEEE standard _______ specifies the most famous family of wireless local area

network.

(a) 800.00 (b) 802.11 (c) 802.1X (d) none of these.

Ans.802.11

Q.9.WML Stands for _______.

(a) Wide mobile landing (b) wireless markup language (c) wireless made language (d) none

of these.

Ans. Wireless markup Language

Q.10.The HTTP is a stateless, _______, application level protocol for data transfer between

server and client.

(a) Lightweight (b) strong (c) heavy (d) none of these.

Ans. Lightweight.

Short Answer Type Questions (2*5=10Marks)

Q.1.Define files systems?

Ans.

Fig.1. File system in Wireless System.

The general goal of a file system is to support efficient, transparent and consistent access to

file. To support mobility, it also provide identical views on directories, file name, access

right and independent of current location.

Q.2. Define Geostationary earth orbit?

Ans.

Fig.2. Geostationary orbit.

Geostationary earth orbit is that orbit having a distance of almost 36000km to the earth. In

this orbit the satellite are basically used for TV and radio broadcast , weather broadcast

and telephone network etc.

Q .3.Define Space division multiple access (SDMA)?

Ans.

SDMA is used for allocating a separate space to user in wireless network, and assigning a

optimal base station to mobile phone user. The basics for SDMA algorithm is formed by

cell sectorized antenna for the constitute the infrastructure implementing of Space division

multiplexing.

Q.4. what is ad-hoc network?

Ans.

Fig.4. Ad-hoc network.

Ad-hoc wireless network do not need any infrastructure, and no asses point controlling

medium is necessary. Each node can communicate directly with other node by using

different carrier frequency.

Q.5.Define network layer?

Ans.

Fig.5. Network Layer.

Network layer is responsible for routing packets, addressing, handover between different

networks etc.

Section B

Each Question carries 8 marks. (Long answer type questions 8*5 =40 Marks)

Note: Attempt any one questions out of two questions from each unit.

Unit 1

Q.1.Explain in detail the concept of spread spectrum techniques and its type?

Ans.

Fig.6

Following are the points of spread spectrum

a. It spread the bandwidth needed for transmission

b. It provide resistance to narrowband interference

c. It minimizes the level of noise and disturbances

d. It deals with narrowband interference for a single channel as well as several channels .

Fig.7

It is divided into two parts

Fig.8

A. Direct sequence spread spectrum: It takes a user bit stream and perform an XOR with

chipping sequence

Fig.9

In the first step the spreading of user data (data message) with the chipping sequence. Then

the spread signal is modulated with radio carrier (radio modulation). The radio carrier

then shifts this signal to carrier frequency. This signal is then transmitted. The receiver

receive the signal the and perform the two inverse function of transmitted modulation

B. Frequency hopping spread spectrum: Bandwidth is split in many channels of small

bandwidth plus guard spaces between the channels.

It is basically divided in to two parts

a. Slow hopping: In the fast hopping System the transmitter changes the frequency several

times during the transmission of single bit.

Fig.10. Frequency hopping.

b. Fast hopping: Fast hopping system transmitter and receiver have to stay synchronized

within smaller tolerance to perform hopping at more or less the same point at a time.

Q.2.What is Medium access control (MAC) explain its function, also explain the concept of

Hidden and exposed terminals?

Ans.

Fig.11

Functions of MAC

a. It provides a point to point or point to multipoint connection.

b. Its data link control layer controls the congestion in network.

c. logical link control is basically used to hopping and multiplexing of channels.

d. It manages the frame control during the transmission of data (In bits).

e. It provides a power full power management system during the transmission and

receiving of data.

f. It synchronizes the internal and external clock pulses of transmitter and receiver .

g. It provides a facility of management information base.

h. It provides the concept of roaming in different network system.

Concept of hidden and exposed terminals.

In the hidden and exposed terminals, the collision and interference of frequency is

minimized by hiding the exposed terminal virtually. In hiding and exposed terminals the

collision detection is found out and at certain level it is minimized the interference of

frequency.

Unit 2

Q.1.Explain in detail the advantages and disadvantage of Geostationary earth orbit (GEO).

?

Ans.

Fig.12

Following are the advantages of GEO

a. Enough to cover all sport of earth.

b. Sender and receiver can used fixed antenna

c. No exhibit Doppler shift because relative movement is zero

d. It is ideal for TV, weather and radio broadcasting

f. Its life time expectation is higher about 15 years.

g. Only three GEO satellites are enough to cover whole surface of earth

Following are the disadvantage of GEO.

a. Cause problem of battery device

b. Cause problem in voice and data communication at high latency.

c. Needs special antennas to focus on small footprint.

d. Due to larger footprint its frequency cannot be reused.

Q.2.Explain in detail the advantages and disadvantages of Low earth orbit (LEO) in

satellite system?

Ans.

Fig.13

Following are the advantage.

a. Use advanced compress schemes.

b. Better frequency reuse.

c. It provides bandwidth for mobile terminals.

Following are the disadvantage

a. It requires many satellites for global coverage.

b. Require additional coverage for handover conditions

d. Its short life time of five to eight years.

Unit 3

Q.1.Explain in detail the working of Radio access layer (RAL) in wireless ATM?

Ans.

Fig.14

Working of RAL to provide a balance full access of transmission of frequency and properly

maintaining the quality of services.

Following are the working of RAL

a. To create a Flexibility environment in radio coverage area.

b. Panning and designing of radio frequency and its properly distribution.

Fig.15

c. To minimize the congestions and traffic problems in routing of packets

d. The implementation of regulation according to rules.

e. It manages the air interference, frequency, modulation , power transmission.

f. It manages the link manager protocol system

g. It manages the Logical link control and adaptation protocol and service discovery

protocol.

h. It manages the synchronous connection – oriented link.

Q.2. What are the services provided by Wireless ATM(WATM) , explain it in detail ?

Ans.

Fig.16

Following are the services provided by Wireless ATM.

a. Office Environment: It provide broad range of internet or intranet access

b. University school, tanning center: Focus on the scenario are distance learning.

c. Industry: In industry information retrieval, and factory management.

d. Hospital: Remote monitoring of patient record

e. Home: Many electronic devices are connected using WATM.

f. Network vehicles: Local access of network and its utilizations.

Unit 4

Q.1.Expalin the advantages of I-TCP (indirect transmission protocol ) in detail ?

Ans.

Fig.17

Following are the advantages of I-TCP

a. Lost packets can’t propagate in to fixed network.

b. I- TCP does not require any change in TCP protocol as used by host in fixed network.

c. An optimized I-TCP use precise time-out to guarantee retransmission as fast as possible.

d. Partitioning in to two connections allows the user to connect different transport layer

protocol between the foreign agent.

Q.2.Explain the disadvantages of I-TCP (indirect transmission protocol) in detail?

Ans.

Fig.18

Following are disadvantages of I-TCP

a. The loss of end – to-end semantic of TCP might cause problem.

b. Increases the handover latency

c. The foreign agent has to integrate in to all security mechanism.

Unit 5

Q.1.Explain the concept of Hypertext markup language in detail ?

Ans.

Fig.19

HTML contain the web pages in the world wide web. It is design to connect the desktop

computers to internet with fixed wire.

Some of the approaches that might help wireless access of HTML.

a. Image Scaling: If a page contains a true color, high – resolution pictures, the pictures can

be scaled down to fewer colors, lower resolutions of just tilt of pictures.

b. Contain Transformation :Many documents are not available in certain formats , a

special converter could translate could translate in to plain text.

c. Content Extraction: Headline or keywords could be extracted from a document and

could be present to user.

d. Special language and protocol: HTML and other protocol adopt better in wireless

environment.

e. Push Technologies: The server could push containing to a client

f. It provide the facility of connection reuse between client and server.

g. Creating facility of catching enhancement so that the bandwidth can be used in more

efficient way.

h. Bandwidth optimization and security are provided by HTML.

Q.2.Explain the concept of wireless Application environment in detail?

Ans.

Fig.20

Wireless application environment having certain applications as

a. Service provider.

b. Software manufacturer

c. Providing services to wireless telephony applications.

d. Provides facility to decode in a gateway.

f. It uses a concept of wireless markup user agent system.

g. It uses gateway to encode the messages.