Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 7th Sem Old 171004 Wireless Communication Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII (OLD) EXAMINATION ? WINTER 2018
Subject Code: 171004 Date: 29/11/2018
Subject Name: Wireless Communication
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Give full forms of the following acronyms: HSCSD, GPRS, WLL, CDMA, WLAN,
MAN, WAN.
07
(b) Draw a neat sketch of GSM architecture and state the functions of the following:
BSC, MSC, VLR, HLR, AUC.
07
Q.2 (a) Explain the salient features of Bluetooth technology. 07
(b) Briefly discuss security threats in wireless network and suggest possible ways of
protection.
07
OR
(b) Explain the hidden-node problem and exposed-node problem in context of mobile
ad-hoc networks.
07
Q.3 (a) Explain practical handoff considerations.
(b) A spectrum of 30 MHz is allocated to a wireless FDD cellular system which uses
two 25 kHz simplex channels to provide full duplex voice and control channels.
Compute the number of channels available per cell if a system uses (i) 4-cell reuse
(ii) 7-cell reuse and (iii) 12-cell reuse. If 1 MHz of the allocated spectrum is dedicated
to control channels, determine an equitable distribution of control channels and voice
channels in each cell for each of the three systems.
07
OR
Q.3 (a) Explain the concept of cell sectoring and how it affects interference and system
capacity.
07
(b) For given path loss exponent (A) n=4 and (B) n=3, find the frequency reuse factor
and the cluster size that should be used for maximum capacity. The signal to
interference ratio (S/I) is required to be at least 15 dB for satisfactory system
performance. There are six co-channel cells in the first tier and all of them are at the
same distance from the mobile. Use suitable approximations.
07
Q.4 (a) Explain salient features of CDMA. 07
(b) Prove that for a regular hexagonal geometry, the frequency reuse ratio and cluster
size are related by the relationship Q = (3N)
1/2
, where N= i
2
+j
2
+ij.
07
OR
Q.4 (a) Explain the working of RAKE receiver with neat diagram. 07
(b) Derive an expression for total received field at a distance d for ground reflection
model.
07
Q.5 (a) Discuss GSM channel types in details. 07
(b) In a cellular radio operating at 800 MHz, the transmitter and the receiver are
separated by 500m from each other. The knife-edge diffraction object between them
has a height of 30 m. The diffraction object is 100 m from transmitter. Find:
(i) The excess path length
(ii) The phase difference corresponding to the excess path length.
(iii) The Fresnel-Kirchhoff diffraction parameter.
(iv) The radius of the second Fresnel zone.
07
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII (OLD) EXAMINATION ? WINTER 2018
Subject Code: 171004 Date: 29/11/2018
Subject Name: Wireless Communication
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Give full forms of the following acronyms: HSCSD, GPRS, WLL, CDMA, WLAN,
MAN, WAN.
07
(b) Draw a neat sketch of GSM architecture and state the functions of the following:
BSC, MSC, VLR, HLR, AUC.
07
Q.2 (a) Explain the salient features of Bluetooth technology. 07
(b) Briefly discuss security threats in wireless network and suggest possible ways of
protection.
07
OR
(b) Explain the hidden-node problem and exposed-node problem in context of mobile
ad-hoc networks.
07
Q.3 (a) Explain practical handoff considerations.
(b) A spectrum of 30 MHz is allocated to a wireless FDD cellular system which uses
two 25 kHz simplex channels to provide full duplex voice and control channels.
Compute the number of channels available per cell if a system uses (i) 4-cell reuse
(ii) 7-cell reuse and (iii) 12-cell reuse. If 1 MHz of the allocated spectrum is dedicated
to control channels, determine an equitable distribution of control channels and voice
channels in each cell for each of the three systems.
07
OR
Q.3 (a) Explain the concept of cell sectoring and how it affects interference and system
capacity.
07
(b) For given path loss exponent (A) n=4 and (B) n=3, find the frequency reuse factor
and the cluster size that should be used for maximum capacity. The signal to
interference ratio (S/I) is required to be at least 15 dB for satisfactory system
performance. There are six co-channel cells in the first tier and all of them are at the
same distance from the mobile. Use suitable approximations.
07
Q.4 (a) Explain salient features of CDMA. 07
(b) Prove that for a regular hexagonal geometry, the frequency reuse ratio and cluster
size are related by the relationship Q = (3N)
1/2
, where N= i
2
+j
2
+ij.
07
OR
Q.4 (a) Explain the working of RAKE receiver with neat diagram. 07
(b) Derive an expression for total received field at a distance d for ground reflection
model.
07
Q.5 (a) Discuss GSM channel types in details. 07
(b) In a cellular radio operating at 800 MHz, the transmitter and the receiver are
separated by 500m from each other. The knife-edge diffraction object between them
has a height of 30 m. The diffraction object is 100 m from transmitter. Find:
(i) The excess path length
(ii) The phase difference corresponding to the excess path length.
(iii) The Fresnel-Kirchhoff diffraction parameter.
(iv) The radius of the second Fresnel zone.
07
2
OR
Q.5 (a) List types of diversity techniques and explain any two of them in 3-4 sentences. 07
(b) If a baseband binary message with a bit rate of 100 kbps is modulated by an RF
carrier using BPSK. Calculate the following:
(i) Find the range of values required for rms delay spread of the channel such that the
received signal is a flat-fading signal.
(ii) If the modulation carrier frequency is 5.8 GHz, what is the coherence time of the
channel for vehicle speed of 50 km/h.
(iii) For your answer in part (ii), is the channel ?fast? or ?slow? fading?
(iv) Given your answer in (ii), how many bits are sent while the channel appears
static?
07
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This post was last modified on 20 February 2020