DOEACC C Level Course-Wireless and Mobile Networks previous years question papers

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1.
a) What is dopplet effect in mobile radio propagation?
b) How do mobile services provide the facility of radio?
c) What is the difference between CSMA/CD and CSMA/CA?
d) What is channel allocation for one dimensional system? List its techniques.
e) What is SMS broadcasting service? Explain its security aspects.
f) Explain 1595 digital cellular standards.
g) Explain Direct Sequence and Spread Spectrum Technology.
(7x4)
2.
a) What are key characteristics of wireless networks that impact TCP’s performance? Explain,
how they impact performance of TCP.
b) Explain working of Mobile IP with the help of a suitable example where a correspondent
node communicates with another mobile node.
(6+12)
3
a) What is wireless local loop (WLL) explain its architecture? How is it different from wireless
local link?
b) What are connections based protocols? Define and explain working of any two such
protocols.
(9+9)
3
a) What is IEEE 802-11 standards for WLAN? Explain different types of WLAN.
b) How does the mobile phone support Internet? How one application can used by mobile as
well as computer using internet?
c) What is universal mobile telecommunication system? Explain the significance of SIM in
mobile services.
(6+6+6)
5
a) Can we apply OSI reference model for the mobile network? Justify your answer.
b) List and give advantages and disadvantages of different transmission media for wireless
local area network (WLAN).
(6+12)
6.
a) Is routing significant for the wireless network? Explain your answer in detail.
b) What are mobile ad hoc networks? How are they formed? Classify the data and control
packet routing in mobile ad hoc networks.
(6+12)
7. Write short notes on the following:
a) Wireless ATM
b) Co-channel interference
c) Frequency reuse

1.
a) Explain Handover mechanism in satellite systems.
b) Briefly explain the operation of mobile IP.
c) Compare the efficiency of ALOHA and slotted ALOHA.
d) What are the advantages and disadvantages of SIP and H.232?
e) Draw block diagram of frequency hopping system for one channel modulation.
f) How is GPRS an enhancement on GSM?
g) Explain Ultra Wideband (UWB) with bandwidth specification.
(7x4)
2.
a) What are the goals and features of Universal Mobile Telecommunication System
(UMTS)? Discuss UMTS architecture.
b) Discuss Quadrature Phase Shift Keying (QPSK) modulation scheme in detail. Why is it
preferable to use Offset Quadrature Phase Shift Keying (OQPSK) instead of QPSK?
(10+8)
3.
a) Discuss briefly the cellular standards of 1G, 2G and 3G systems.
b) Explain GSM protocol model and mobility management.
(9+9)
4.
a) Determine capacity of cellular CDMA. How does it depend on the processing gain?
b) What is fading? Explain types of fading based on multi path time delay spread and
doppler spread.
(9+9)
5.
a) What is channel allocation? Explain Dynamic channel allocation.
b) Discuss security issues in WLAN’s.
c) How is Wireless-ATM suitable for multimedia applications?
(8+5+5)
6.
a) Explain Bluetooth Architecture and protocol stack. List the application of Bluetooth.
b) Explain the operation of IEEE 802.11 WLAN protocol.
(10+8)
7.
a) Why is CSMA/CD not suitable in WLAN’s? Explain with examples.
b) Explain the concept of cell splitting and cell sectoring.
c) Explain network management in Local Multipoint Distribution Service (LMDS).
(6+6+6)

1.
a) Why do paging systems need to provide low data rates? How does a low data rate lead
to better coverage?
b) Discuss the similarities and differences between a conventional cellular radio system
and a space based (satellite) cellular radio system.
c) Explain the concept of coherence bandwidth.
d) Explain cell sectoring and cell splitting with its advantage.
e) Why are Wireless Local Loops (WLLs) effective in communications?
f) Explain the process of registration of a mobile station in satellite networks.
g) What is UWB (Ultra Wide Band)? Explain various applications of it.
(7x4)
2.
a) How is hidden node problem solved in WLANs?
b) Explain data exchange and backoff procedures in IEEE 802.11 protocol. Use
appropriate diagrams.
c) Classify routing procedures in WLANs.
(6+9+3)
3.
a) Explain the inefficiencies of mobile IP regarding data forwarding from a corresponding
node to a mobile node. What are the optimizations and what additional problems do they
cause?
b) Why is TCP not useful in mobile networks? Give reasons.
(9+9)
4.
a) What is Frequench-Hopping Spread Spectrum (FHSS) in wireless local area network?
What are the advantages offered by spread spectrum transmission over fixed frequency
transmission?
b) Explain QPSK using transmitter and receiver Block diagram. Compare its features with
BPSK.
(8+10)
5.
a) Explain protocol model and typical call flow sequence in IS-136: North American TDMA
standard.
b) What is the motivation to implement Wireless ATM (WATM)? Describe the WATM
architecture.
c) Briefly explain the main layers of Bluetooth protocol stack. Also clearly mention the
developing advantage of Bluetooth protocol.
(5+7+6)
CE2-R3 Page 1 of 2 January, 2008
1. Answer question 1 and any FOUR questions from 2 to 7.
2. Parts of the same question should be answered together and in the same
sequence.
6.
a) How can higher data rates be achieved in standard GSM, how is this possible with the
additional GPRS, EDGE? What are the main differences of the approaches, also in
terms of complexity? What problems remain even if the data rate is increased?
b) Explain static and dynamic channel allocation (assignment) methods. Compare their
effectiveness in cellular systems.
(10+8)
7.
a) Name the main elements of the GSM system architecture and describe their functions.
b) What are the main benefits of a spread spectrum system? How can spreading be
achieved?
c) What is Co-channel Interface (CCI) in GSM? Obtain an expression for Signal to
Interference Ratio (SIR) when the interference is CCI.
(5+5+8)

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Sometimes when a cellular user crosses the boundary from one cell to another, the current call is abruptly terminated, even though all transmitters and receivers are functioning perfectly. Why?
What is the difference between adjacent channel interference and co-channel interference?
Sometimes the user is moving within the cell towards the BSS and experiences sudden loss in signal strength. What is it due to? What are the factors responsible for temporary signal loss?
Why are GEO systems for telecommunications currently being replaced by fiber optics?
Why the collision avoidance is used in the wireless ad-hoc networks/WLAN in place of the collision detection methods?
How is Ultra Wide Band (UWB) different from frequency hopping used in Blue-tooth?
Prove that the capacity of WLL is independent of the path loss.
Differentiate between wireless and fixed networks. What are the time limitations in wireless networking?
Show that the magnitude (envelope) of the sum of two independent identically distributed
complex (quadrature) Gaussian sources is Rayleigh distributed. Assume that the Gaussian
sources are zero mean and have unit variance.
The US Digital Cellular TDMA system uses a 48.6 kbps data rate to support three users per frame. Each user occupies two of the six time slots per frame. What is the raw data rate provided for each user?
Using a concentric Cellular geometry determine recursive expressions for the two weighting factors for the equivalent hexagonal geometry for the second layer and all subsequent layer cells
Show how to integrate the registration and the authentication procedures in GSM.
Which of the following is a blank-and-burst channel in AMPS system? Elaborate.
i) Paging Channel
ii) Reverse Voice Channel
iii) Slow Associated Control Channel
iv)Fast Associated Control Channel
What mechanisms would cause breakdown in the reverse link of an IS-95 CDMA System
as the number of users in a sector approaches the theoretical limit.
Discuss the similarities and differences between a Conventional Cellular Radio System and Satellite Based Radio System. Which system would support a larger number of users for a given frequency allocation? Why?
Compare the Infrared Transmission Technology with Radio Transmission Technology used in WLANs. Discuss the problem of hidden terminals. How is it solved?
What are the different techniques used for Improving Coverage and Capacity in Cellular
System? How co-channel interference is reduced using sectoring?
What is the need for security in Blue-tooth system? How does authentication take place
between two Blue-tooth devices? Use diagrams to support your explanation.
Discuss various channel allocation technologies used in WLANs? Compare fixed and
dynamic channel allocation schemes
DOEACC C Level Course-Wireless and Mobile Networks previous years question paper
1.
a) If a complete coverage area was redesigned using larger cluster sizes, what will most
likely be the effect on adjacent channel interference? Why?
b) What is difference between co-channel and adjacent channel interference? Give two
methods to reduce these interferences.
c) Give the expression for path loss. Differentiate between slow fading and fast fading.
d) Draw and explain the operation of QPSK transmitter. Give its truth table and
constellation diagram.
e) Explain the terms and the functions of WANU and WASU as used in the TR-45
architectural reference model of WLL.
f) Explain the MACA protocol and tell how hidden terminal and exposed terminal problem
can be solved. How is MACA different from MACAW?
g) Compare and contrast different satellite configurations. Which one is most suitable for
satellite based cellular mobile operations.
(7x4)
2.
a) Explain the concept of frequency reuse. Define and deduce co-channel
interference reduction factor. Find its value for k=7.
b) Define the TDMA, FDMA and CDMA. Why is CDMA the most sought after multiple
access technique in 3G?
c) Prove that N= i2 + g2 + ij & D= R Ö3N.
(8+6+4)
3.
a) Deduce the relationship of received power (Pr) at a distance (d) in a wireless
communication system using two-ray model.
b) Discuss different fixed channel assignment Strategies. What are its limitations as compared
to non-fixed channel assignment methods?
c) What is cell splitting?
(8+8+2)
4.
a) Draw the basic reference architecture and signaling interfaces for GSM. Why is Smart card
needed in GSM, while it is not required in AMPS?
b) 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.
c) Advantages of digital cellular systems over analog.
(8+8+2)
5.
a) Describe the GPRS architecture and its protocols.
b) Compare GPRS with CDPD. What are the fundamental differences between the two
services and what are the guidelines shared by them.
c) What are enhanced features in EDGE, which are not present in GPRS.
(6+6+6)
6.
a) With the help of a neat block diagram explain TR-45 Wireless Local Loop Reference
model?
b) Describe the WLL OAM Management functions.
c) Discuss the characteristics of UWB system. Also draw the advantages and limitations of
UWB technology.
(6+6+6)
7.
a) Describe the Circuit switched Data on Digital cellular networks. Clearly explain the terms
TRAU and IWF used to support GSM in data transport.
b) What is GMPCS? Explain what are GEO, MEO and LEO systems. Give the call flow
diagram for an ISU and ISU call in iridium system.
c) Write a note on the Wireless Local loop technologies. Describe cellular based systems in
detail.
(6+6+6)

DOEACC C Level Course-Wireless and Mobile Networks previous years question paper
a) What are the distinguishing features in Wireless Communication using GEO and LEO
satellites?
b) With an illustration explain Raleigh fading model used in cellular radio propagation.
c) How does cellular concept help in efficient frequency spectrum utilization?
d) What is QPSK? Give its limitations as compared to QAM.
e) Give an account of dynamic channel allocation methods and why are they more useful
than static channel allocation methods.
f) Why is power control a major issue for operation of CDMA?
g) What are the main deployment issues to deal within WLL? Which of these issues do not
exist in wireline local loop?
(7x4)
2.
a) Why are both DCF and PCF technologies provided in IEEE 802.11 wireless LANs?
b) Distinguish between MACA and MACAW protocols in wireless LANs.
c) What is the hidden node problem in wireless LANs?
(6+6+6)
3.
a) Describe the Circuit-switched Data transfer on Digital cellular networks. Clearly explain
the terms TRAU and IWF used to support GSM in data transport.
b) What are the requirements for transforming multimedia data on wireless networks?
Does wireless ATM is suitable for the above? Give reasons.
(9+9)
4.
a) Draw the basic reference architecture and signaling interfaces for GSM. Why is Smart
card needed in GSM, while it is not required in AMPS?
b) How do you compare D-AMPS and GSM systems in terms of coverage area, transmitted
power and error control system? How are adjacent channel and co-channel
interferences addressed in the above systems?
(9+9)
5.
a) Explain the systems characteristics of UBW and how it can solve the problems of
scarcity of radio spectrum. How is UBW different from frequency hopping as used in
Blue tooth?
b) Why is standard TCP not adequate for mobile wireless networks? Explain, using
suitable diagram.
(9+9)
6.
a) How are slot, frame, multiframe and superframe related in GSM?
b) Deduce the relationship of received power (Pr) at a distance (d) in a wireless
communication system using two-ray model.
c) What is dropped call rate? Give the factors responsible for dropped call rate. Give the
formula for dropped call rate and explain the various factors.
(6+6+6)
7.
a) What is cell sectoring? List its advantages.
b) How can Internet be supported on mobile links. Draw the architecture and functional
components of mobile IP. Describe data transfer from a mobile node to a fixed node and
vice-versa.
c) What are advantages of IPv6 over IPv4? List the entities of mobile IP and describe data
transfer from a mobile node to a fixed node and vice-versa.
(6+8+4)

DOEACC C Level Course-Wireless and Mobile Networks previous years question paper
a) Radio waves are electromagnetic waves occurring on the radio frequency portion of the
electromagnetic spectrum. How is it produced and propagated?
b) The increased capacity in a cellular network, compared with a network having single
transmitter, comes from the fact that the same radio frequency can be reused in a different
area for a completely different transmission. What should be the frequency reuse factor
when same frequency is used in the single network? Justify your answer.
c) What is the meaning of multiple accesses with respect to wireless network? List the types of
multiple access presently used in communication satellite.
d) Channel, in communications, refers to the medium used to convey information from a
sender to a receiver. What are the different forms of it?
e) In telecommunications, direct-sequence spread spectrum (DSSS) is a modulation
technique. What are the features and benefits of Direct Sequence Speed Spectrum (DSSS)
techniques in telecommunications?
f) What are the reasons that a mobile device provides updated location information to the
network? Briefly explain location update procedure.
g) Explain, how Code Division Multiple Access (CDMA) works.
(7x4)
2.
a) The main difference between 1G and 2G mobile telephone system that the first is analog
and the second is digital. What are the advantages and disadvantages of using digital
systems?
b) Categorize and briefly explain the satellite system based on the orbit type and altitude
specification.
c) Define the term UWB (Ultra Wide Band). Explain various applications of it.
(8+6+4)
3.
a) Explain what is piconet and personal area network. How are they used in Bluetooth?
b) What is wireless in local loop (WLL)? What are the different standards of it?
c) The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol.
Define SIP and briefly explain its features.
(8+6+4)
4.
a) Define the term Hand Off in cellular telecommunication and explain what are the
reasons for conducting hand off and hand over?
b) Why channel allocation schemes are required in TDMA/FDMA based cellular radio
systems and wireless networks? What are the different types of it? Compare dynamic
channel allocation scheme with spread spectrum technique.
(8+10)
5.
a) How does an Enhanced Data rate for GSM Evolution (EDGE) or Enhanced GPRS
(EGPRS) technology improve data transmission reliability? Explain its architecture,
features and applications.
b) What is Frequency-hopping spread spectrum (FHSS) in wireless local area network?
What are the advantages offered by spread spectrum transmission over fixed frequency
transmission?
(10+8)
6.
a) What is fading? Explain types of fading based on multi path time delay spread and
Doppler spread.
b) How does Mobile IP work, when a mobile user moves from one network to another and
maintaining a permanent IP address?
(10+8)
7.
a) What is ALOHA and slotted ALOHA? How throughput is calculated in slotted ALOHA?
What are the steps to stabilize slotted ALOHA?
b) Bluetooth is a wireless communication protocol. Briefly explain the main layers of
Bluetooth protocol stack.
c) What is W-CDMA (Wideband Code Division Multiple Access)? Describe its key features
and briefly explain how is it different from other multiple access mechanism?
(8+4+6)

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