Unit 1

PART A
Define Cell, Cluster
State the use of cell splitting
Describe the techniques used to expand the capacity of the cellular system?
Report about Soft and hard handoffs?
Define frequency reuse technique
Explain the methods used to reduce adjacent channel interference
State the importance of Channel assignment techniques.
Calculate the number of simultaneous users in a GSM system, assuming a TDMA/FDD
system with a 25 MHz forward link, where each radio channel occupies 200 kHz without
any guard band.
Explain the effects of near/far problem influence in wireless communication
Summarize about the Cell Splitting and Cell Sectoring
Compile the important Handoff
PART B
Analyze 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. Compute the number of channels available per
cell if it uses 4 cell reuse.
i. Apply the techniques used to improve coverage and channel capacity in cellular
systems and demonstrate how each enhances system performance
ii. Illustrate with examples how different techniques can be applied to improve
coverage and capacity in cellular systems
i. Appy the concept of frequency reuse, If a signal to interference ratio of 15 dB is
required for satisfactory forward channel performance of a cellular system, what is
the frequency reuse factor and cluster size that should be used for maximum
capacity if the path loss exponent is (a) n = 4 (b) nt = 3? Assume that there are 6
co-channels cells in the first tier, and all of them are at the same distance from the
mobile. Use suitable approximations.
ii. Solve by using GSM, uses a frame structure where each frame consists of 8 time
slots, and each time slot contains 156.25 bits, and data is transmitted at 270.833
kbps in the channel, find (a) the time duration of a bit, (b) the time duration of a
slot,(c) the time duration of a frame, and (d) how long must a user occupying a
single time slot must wait between two simultaneous transmissions
i. Apply the concept of trunking and Grade of Service to demonstrate their role in
improving the efficiency of cellular systems
ii. Illustrate the application of frequency reuse in cellular networks by showing how it
enhances system capacity and coverage
Derive an expression to reduce co channel interference experienced by edge user in seven
cell reuse cellular architecture
 i. Describe how bandwidth allocation and channel reuse affect the number of
available control and voice channels in a cellular system. A cellular system with a
total bandwidth of 15 MHz uses 10 KHz simplex channels to provide full duplex
voice and control channels. For 12 cell reuse pattern and 1 MHz of the total
bandwidth is allocated for control channels.
a. Calculate the total available channels.
b. Determine the number of control channels.
c. Calculate the number of voice channels per cell.?

(ii) In a cellular system with total of 917 radio channels available for handling traffic. The
area
of a cell is 4 km2 and the total area is 1400 km2 with cluster of 7.
(a) Calculate the system capacity.
(b) How many times signal can be replicated?
(c) Calculate the system capacity for N = 4.
(d) Compare the performance.
Summarize how co-channel interference and adjacent channel interference influence the
capacity and quality of service in a cellular system.
i. Interpret how the cellular service provider that decides to use a digital TDMA
scheme which can tolerate a signal –to-interference ratio of 15dB in the worst case.
Find the optimal value of N for
a. Omni directional antennas
b. 120° sectoring
c. 60° sectoring
d. Should sectoring be used? If so, which case (120°or 60°) should be used?
(Assume a path loss exponent of n=4 and consider trunking efficiency?

ii. If signal-to-interference ratio of 15dB is required for satisfactory forward channel

performance of a cellular system, what is the frequency reuse factor and cluster size
that should be used for Maximum capacity if the path loss exponent is
a. (1) n=4 (2) n=3?
Outline in detail about the handoff strategies involved in cellular systems.
i. Apply the concept of frequency reuse and channel reuse , If a total of 33 MHz of
bandwidth is allocated to a particular FDD cellular telephone 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 (a) 4-cell reuse,
(b) 7-cell reuse (c) 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
Applying the concept of power conversion, Assume if a transmitter produces 50W of
power, express the transmit power in units of dBm and dBW. If 50W is applied to a unity
gain antenna with a 900 MHz carrier frequency, finding the received power in dBm at a
free space distance of 100m from the antenna also justify the analytical expression by
computing the received power at 10km.
(i) Explain the concept of frequency reuse in cellular systems.
(ii) Examine about channel assignment strategies in detail.
(i) Explain the role of repeaters in extending the range of communication systems.
(ii) illustrate the microcell zone concept for enhancing cellular network capacity.
Unit 2

Differentiate between small Scale fading and Large scale fading

Summarise about the Brewster angle
Define Coherence bandwidth
Assess the effects of Doppler Shift.
Identify the different propagation mechanisms in mobile radio.
Calculate the far-field distance for an antenna with a maximum dimension of 2 m operating
at 1 GHz frequency.
Calculate coherence time, Doppler spread for carrier frequency fc = 1900 MHz and V = 50
m/s of moving vehicle distance of 10 m
Compare Small scale fading based on multipath time delay and Doppler spread.
Differentiate between coherence time and coherence bandwidth.
Identify the Fraunhofer distance for an antenna with maximum dimension of 1m and
operating frequency of 900 MHz If antenna has unity gain, calculate the path loss
Identify the different propagation mechanisms in mobile radio.
Calculate the far-field distance for an antenna with a maximum dimension of 2 m operating
at 1 GHz frequency.
PART B
A mobile is located 10 Km away from a base station and uses a vertical λ/4 monopole antenna
with a gain of 3 dB to receive cellular radio signals. The E-field at 1 km from the transmitter is
measured to be 10 V/m. The carrier frequency used for this system is 1000 MHz.
–3

a. Find the length and effective aperture of the receiving antenna

Find the received power at the mobile using the two-ray ground reflection model assuming h t

is 50 m and h is 1.5 m above ground.

r

(OR)
i. Calculate coherence time, Doppler spread for carrier frequency fc = 1900 MHz and V
= 50 m/s of moving vehicle distance of 10 m

ii. If a transmitter produces 50W of power, express the transmit power in units of (a)
dBm, and (b) dBW. If 50W is applied to a unity gain antenna with a 900 MHz carrier
frequency, find the received power in dBm at a free space distance of 1000m from the
antenna. What is Pr(10km)?

i. Derive the free space propagation model and discuss the understanding on propagation
mechanism influencing fading in wireless channel
ii. Find the Fraunhofer (far-fied) distance for an antenna with maximum dimension of 1m
and operating frequency of 9000 MHz. If antennas have unity gain, calculate the path
 loss.
(OR)
i. Explain fading effects due to multipath time delay spread and fading effects due to
Doppler spread?
ii. List the factors influencing small scale fading and explain the factors
i. Explain in detail about fast fading and slow fading in wireless channel.
ii. Write the effects of fading
(OR)
i. If a transmitter produces 50W of power, express the transmit power in units of (a)
dBm, and (b) dBW. If 50W is applied to a unity gain antenna with a 900 MHz carrier
frequency, find the received power in dBm at a free space distance of 1000m from the
antenna. What is Pr(10km)? Assume unity gain for the receiver antenna
ii. Explain in brief about the three propagation mechanisms.

Consider a transmitter which radiates a sinusoidal carrier frequency of 2000 MHz For a
vehicle moving 100 mph, compute the received carrier frequency if the mobile is moving
a. directly toward the transmitter
b. away from the transmitter
c. direction which is perpendicular to the direction of arrival of the transmitted
signal.

ii. Calculate coherence time, Doppler spread for carrier frequency fc= 1900 MHz and V = 50
m/s of moving vehicle distance of 10 m

(OR)

Derive with the expressions for the concepts

a. Doppler shift,
b. Doppler spread,
c. Coherence time.
d. Apply these to compute the Doppler spread and coherence time for a mobile
system operating at a carrier frequency of 2 GHz with a vehicle speed of 100
km/h.

ii. Analyze and compare the impact of fast fading and slow fading on system performance by
considering a wireless channel with a delay spread of 5 µs and a Doppler frequency of 200
Hz.

Explain the reflection, diffraction, and scattering influence signal propagation in free space.
(OR)
If a transmitter produces 50W of power, express the transmit power in units of (a) dBm, and
(b) dBW.
If 50W is applied to a unity gain antenna with a 900 MHz carrier frequency, find the received
power in dBm at a free space distance of 1000m from the antenna. What is Pr(10km)? Assume
unity gain for the receiver antenna
i. illustrate the following
 (a) Doppler shift,
(b) Doppler spread,
(c) Coherence time. Calculate the Doppler spread if the carrier frequency is 1900 MHz
and velocity is 50 m/s.
What is free space propagation model? Write the expression for free space path loss.
(OR)
If a transmitter power is 1 W and carrier frequency is2.4GHz and the receiver is at a distance
of 1 mile(1.6Km) from the transmitter. Assume that the transmitter and receiver antenna gain
are1.6
a. What is the received power in dBm in the free space of signal?
b. What is the path loss in dB
c. What is the transmission delay in ns
Examine the effectiveness of flat fading and frequency selective fading

Unit 3
PART A

Differentiate between MSK and GMSK.

Interpret the reason why MSK is referred to as fast FSK?
Explain the role of a Gaussian filter in GMSK modulation and why it is necessary.
Describe how a pseudo-noise sequence is generated
Explain why MSK is referred to as fast FSK.
Define Spread Spectrum

PART B
Explain in detail about Gaussian Minimum Shift Keying transmission and reception with
necessary block diagram
Explain the process of generating pseudo-noise (PN) sequences and illustrate with an example.
Describe the working principle of MSK modulation and derive the expression for its power spectral
density.

Analyze the transmitter and receiver mechanism in and their PSD of GMSK modulation, and
draw the necessary block diagrams
Explain about the working of DS-SS with a neat block diagram
i. Illustrate the factor that influence the choice of digital modulation
Examine the principle working of MSK modulation and derive the expression for power
spectral density