Revision Week, Fall 2008 Lecturer Madeeha Owais. Syllabus Satellite Communication – Link Budget or Link Design Calculations Part (Chapter 4 from Timothy.

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?

10

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

12

( ) 20log ( )dG dB F v

13

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.

14

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.

15

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:

16

1 2

1 2n

n d dr

d d

Example 4.8

• As done on board!!!