Revision Week,
Fall 2008
Lecturer Madeeha Owais
Syllabus
• Satellite Communication
– Link Budget or Link Design Calculations Part
(Chapter 4 from Timothy Pratt Book)
– Satellite Multiple Access
(Reading reference pages from Timothy Pratt book
specified in lecture slides)
All this portion has been covered in Class Lectures in
Lecture 5 to Lecture 10
(Downloadable from Website)
• Cellular Communication
– The Cellular Concept-System Design Fundamentals
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•
•
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Chapter 3 from Rappaport Book
Class Lectures: Cellular Concept (Lecture 1 to Lecture 4)
Lectures are downloadable from website
Video Lectures: Specially Lecture 6
• Cellular Communication
– GSM
• Lesson 1 to 6 of the CBT
• Do go through Lesson 7 of CBT for better clarity/flow
understanding of things learnt in Lesson 1 to 6
• GSM Authentication Tutorial(Downloadable from
website, Studied in Class)
• Page 549-563 of Rappaport Book, especially for GSM
Channel Types and Frame Structure
• Cellular Communication
– Mobile Radio Propagation: Large Scale Path Loss
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•
•
Chapter 4 from Rappaport Book
Class Lectures: MRP (Lecture 1 to Lecture 3)
Lectures are downloadable from website
Closely follow the instructions I have written down in
lecture slides to read what from where
Video Lectures
• Video lectures can be as additional resource
for cellular communication part.
• Link to access video lectures on YouTube is
given in the Announcements part of the
Website
• You can also take them from me
• Paper would have two parts
– Objective (Max 30 mins)
– Subjective (Max 2 hr 30 mins)
• Paper would consist of:
– Numericals
– Scenario based problems
– Reasoning Explanations as Theory Part
– Answer briefly type questions as given in Midterm
Exam
Sessional Result
• Please see your
sessional result
(out of 40%)today
before leaving the
class!!!
REVISION
• Recursive Model Query of last lecture
• 2 Numerical Examples from Diffraction Topic
in the Chapter 4 of Rappaport Book
• Link Margin Calculation in Satellite
Communication Link Budget
• How Frequency Hopping helps prevent
interference?
• EXAMPLE 4.7 of BOOK, page 132-133!!!
• Compute the diffraction loss for the three cases shown in
figure shown
h
hobs
hobs
h is positive, v is positive
h is zero, v is zero
h
hobs
h is negative, v is negative
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Example 4.7 (contd)
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•
•
•
•
Assume λ=1/3m,d1 =1km, d2 =1km
a)h=25 m
b)h=0m
c)h=-25m
Compare your answers using values from Diffraction Loss
Graph as well as numerical solution from gain equations
• For each of these cases,identify the fresnel zone within which
the tip of the obstruction lies
Diffraction and Fresnel Zones
Gd (dB)  20log F (v)
12
Gd (dB)  0
v  1
(5  a)
Gd (dB)  20 log(0.5  0.62v)
1  v  0
(5  b)
Gd (dB)  20 log(0.5exp(0.95v))
0  v 1
(5  c)
Gd (dB)  20 log(0.4  0.1184  (0.38  0.1v) 2 )
1  v  2.4
(5  d )
 0.225 
Gd (dB)  20 log 

 v 
v  2.4
(5  e)
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Diffraction and Fresnel Zones
Fresnel Zones:
Assume that the obstruction is placed at a distance of d1 from transmitter
and d2 from receiver.
x
b
r1
d1
a
d2
if b = a + λ/2
then point x is said to lie on the 1st fresnel zone.
The loci of all the points which satisfy the above condition will form
a circle.
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Diffraction and Fresnel Zones
Fresnel Zones:
Assume that the obstruction is placed at a distance of d1 from transmitter and d2
from receiver.
b
r1
d1
a
d2
Similarly all the points for which path length for the secondary waves is
greater than the LOS path by λ lie on the 2nd fresnel zone.(i.e. b = a + λ )
Thus the path length of the n-th fresnel zone circles is n λ/2 longer than the
path length of the LOS path.
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Diffraction and Fresnel Zones
Fresnel Zones:
The radius of the n-th fresnel zone circle is denoted by rn and can be
expressed in terms of n, λ, d1, and d2 by:
rn 
n d1d 2
d1  d 2
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Example 4.8
• As done on board!!!