Wireless 03 Large Scale

8/3/2019 Wireless 03 Large Scale

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Electrical & Computer Engineering

Wireless Communications

Channel Modeling Large Scale

Rami Haddad


2/14

Review: Radio Wave Propagation

Wave Propagation Mechanisms & Challenges Reflection, diffraction, and scattering Lack of direct line-of sight path between the Tx and Rx Multipath fading

Large-scale fading: transmission over large T-Rseparation distance (hundreds or thousands

meters)


3/14

Take a look of this case first


4/14

Reflection When a radio wave propagating in one medium

impinges upon another medium have different

electrical properties

The wave is partially reflected The reflection coefficient The material properties The wave polarization The angle of incidence The wave frequency


5/14

Ground Reflection Model

Two-Ray model

ht hr

d

i r

ELOS

Ei Eg

|ETOT|=|ELOS+Eg|

From the laws of reflection we know the following:

Taking notes in class

Eg = Ei

Et = 1+ ( )Ei

i=

r


6/14

Ground Reflection Model Geometry


7/14

Taylor Series

1+h

t+ h

r

d

2

=1+(1)(2)

(1)(4)

ht+ h

r

d

2

= d 1+h

t+ h

r

d

2

d 1+h

t h

r

d

= d 1+

1

2

ht+ h

r

d

2

d 1+

1

2

ht h

r

d

2

= d= d2 d

1= h

t+ h

r( )2

+ d2 h

t h

r( )2

+ d2= d 1+

ht+ h

r

d

2

d 1+h

t h

r

d

2

d d d+1

2dh

t

2 h

t

2+ h

r

2 h

r

2+ 2h

th

r+ 2h

th

r( ) 2h

th

r

d


8/14

Ground Reflection Model The received E-field

ETOT

2E

0d0

d

2hthr

d

The received power at a distance d

Pr= P

tG

tG

rht

2

hr2

d4

d>> ht+ h

r d>10 h

t+ h

r( )

2

=

2hth

r

d

< 0.3rad

Conditions:


9/14

Two-ray Model Path Loss

The path loss is as follows:

PL =Pt

Pr

=

d4

GtG

rht

2hr

2

PL(dB) = 40logd 10logGt+10logG

r+ 20logh

t+ 20logh

r( )

The path loss represented in decibel is as follows:

d>> ht+ h

r d>10 h

t+ h

r( )

2

=

2hth

r

d

< 0.3rad

Conditions:


10/14

Ground Reflection Model

Advantage Consider both the direct path and a ground reflected

propagation path between the Tx and Rx

Disadvantage Oversimplified: does not include factors like terrain

profile and surroundings

Whether the two-ray model could be applied? Case 1: ht=35 m, hr=3m, d=250 m Case 2: ht=30 m, hr=1.5m, d=450 m


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Example: A mobile is located 5 km away from a base station and uses a /4

monopole antenna with a gain of2.55 dB to receive cellular radio

signals. The E-field at 1 km from the transmitter is measured to be

10-3V/m. The carrier frequency used for this system is 900 MHz.

a. Find the length and the effective aperture of the receiving antenna?b. Find the received Power at the mobile using the two-ray ground reflection

model assuming the height of the transmitting antenna is 50 m and the

receiving antenna is 1.5 m above ground.


12/14


13/14

Project Ideas

60 GHz communication Ultra-Wide-Bandwidth Communication

Near-Field Communication

Sub-carrier spacing schemes for 60 GHz OFDM communication systems Rate Adaptive Multi-Code Multi-Carrier CDMA Systems in Multipath Fading

Channel

Fundamental overview and simulation of MIMO systems for Space-Timecoding and Spatial Multiplexing

ICI Cancellation for OFDM Systems Optimal Design for Channel Estimations in OFDM Systems


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More into Ideas

http://www.youtube.com/watch?v=0lvL4SGHY5Y

http://www.youtube.com/watch?v=-5zuOsy40E8

http://www.youtube.com/watch?v=9sn3GFdFC0o

http://www.youtube.com/watch?v=VLAgYUQCgD8

http://www.youtube.com/watch?v=K5IIA07gQTA

Wireless 03 Large Scale

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