revision week, fall 2008 lecturer madeeha owais. syllabus satellite communication – link budget or...
TRANSCRIPT
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• 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• 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
• Please see your sessional result (out of 40%)today before leaving the class!!!
Sessional Result
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?
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hobsh
h is positive, v is positive
hobs
h is zero, v is zero
hobs
h
h is negative, v is negative
• EXAMPLE 4.7 of BOOK, page 132-133!!!• Compute the diffraction loss for the three cases shown in
figure shown
Example 4.7 (contd)
• 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
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( ) 20log ( )dG dB F v
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2
( ) 0 1 (5 )
( ) 20log(0.5 0.62 ) 1 0 (5 )
( ) 20log(0.5exp( 0.95 )) 0 1 (5 )
( ) 20log(0.4 0.1184 (0.38 0.1 ) ) 1 2.4 (5 )
0.225( ) 20log 2.4 (5 )
d
d
d
d
d
G dB v a
G dB v v b
G dB v v c
G dB v v d
G dB v ev
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
a d1 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
a
d1 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:
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1 2
1 2n
n d dr
d d
Example 4.8
• As done on board!!!