aalto university school of electrical engineering elec-e4750 radiowave propagation … · 2016. 11....

Aalto University School of Electrical Engineering

ELEC-E4750 Radiowave Propagation and Scattering Session 8: Cellular links (1)

ELEC-E4750 10.11.2016

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Schedule

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Wk Date Location New topics, lectures and deadlines

43 Tue. 25 Oct. R037/TU3 1194-1195 Thu. 27 Oct.

44 Tue. 01 Nov. Topic 7: wireless and cellular systems Thu. 03 Nov. Clicker lecture 7

45 Tue. 08 Nov. Topic 8: cellular links (1) Thu. 10 Nov. Clicker lecture 8

46Tue. 15 Nov. Topic 9: cellular links (2) Thu. 17 Nov. Clicker lecture 9; threshold deadline of

topics 5-8

47 Tue. 22 Nov. Topic 10: cellular links (3) Thu. 24 Nov. Clicker lecture 10

•  Suzan leads on 25 and 27 Oct. •  Usman is away for 25.9-01.11. •  Usman and Suzan lead on 24 Nov.


Books, Topics and Exercises §  Books

§  Main books §  S. Saunders, Antennas and Propagation for Wireless Communication Systems, Chapters 3, 5,

6-8, 10, 12 15, Wiley. §  H. L. Bertoni, Radio propagation for modern wireless systems, Chapters 2-6, Prentice Hall. §  A. F. Molisch, Wireless Communications, Chapters 1 and 8, Wiley. §  John A. Richards, Radio wave propagation, an introduction for the non-specialist, Chapter 3,

Springer. §  Hardcover or paperback copies of both books are available in AaltoELEC and main

library. §  Supplemental books:

§  D. M. Pozar, Microwave Engineering, Chapter 1, Wiley.

§  Topic 7: Wireless and cellular systems (Ch. 1 of Molisch) §  Exercise 1: Wireless systems §  Exercise 2: Radio standardization

§  Topic 8: Cellular links (1) (Ch. 8 and 12, Ch. 6) §  Exercise 1: Empirical pathloss models §  Exercise 2: Physical pathloss models

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Contact Sessions for Topic 8•  Goals of the present exercise problems are to

–  Get acquainted with the cellular concepts of mobile communications and their most relevant propagation mechanisms (problem 1)

–  Be able to use physical models and compare their merits with respect to empirical models (problem 2)

•  During the contact sessions, you are –  solving the exercise problems by referring to relevant parts of the course

books. •  A limited number of course books are available in the room.

–  encouraged to discuss with other students and teachers. –  asked to contact teachers once your solutions are ready.

•  If you prepare exercise solutions in an electronic format (recommended), upload the solution to MyCourses first and then contact teachers.

–  asked to propose points for your ready solutions to the teachers. –  not given exercise points without discussing with teachers.

•  The discussions MUST happen in the contact sessions. –  reminded that the threshold deadline of Topic 5-8 exercises is November

17th.



Cellular Scenarios

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Satellite links (Mega cells)Macrocells Microcells

Pico cells


Q1a:whichstatementisincorrect?A.  Megacellsareusually

communica2onsbetweenasatelliteandground,liketheglobalposi2oningsystems.

B.  Macrocellsaremoresuitableforservingdenseusersthanpicocells.

C.  Microcellandmacrocellbasesta2onsareusuallyplacedonbuildingwallsandroo?ops,respec2vely.

D.  Theneedofmicrocellsandpicocellsemergedmorerecentlythanmacrocells.


Q1b:whichstatementisincorrect?A.  Megacellsareusually

communica2onsbetweenasatelliteandground,liketheglobalposi2oningsystems.

B.  Macrocellsaremoresuitableforservingdenseusersthanpicocells.

C.  Microcellandmacrocellbasesta2onsareusuallyplacedonbuildingwallsandroo?ops,respec2vely.

D.  Theneedofmicrocellsandpicocellsemergedmorerecentlythanmacrocells.


Q2a:whichstatementisincorrect?A.  Megacellcommunica2onsusually

relyonlyonline-of-sight.B.  Higherradiofrequenciesaremore

suitableformacrocellsthanformicrocells.

C.  Microcellradiopropaga2onisdominatedbyreflec2ons fromwallsina so-calledstreetcanyon.

D.  Pathlossofmicrocellsforindoorusersismainlyaffectedbydiffrac2onintobuildingandpenetra2oninsidethebuilding.


Q2b:whichstatementisincorrect?A.  Megacellcommunica2onsusually

relyonlyonline-of-sight.B.  Higherradiofrequenciesaremore

suitableformacrocellsthanformicrocells.

C.  Microcellradiopropaga2onisdominatedbyreflec2ons fromwallsina so-calledstreetcanyon.

D.  Pathlossofmicrocellsforindoorusersismainlyaffectedbydiffrac2onintobuildingandpenetra2oninsidethebuilding.



Pathloss Models: Applicability•  Can we use the plane-earth pathloss model for studying the

pathloss in macro, micro and picocells?

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TX

RXhb

d

hmPlane earth

From exercise problem 5.1

101 102 103 104 105Distance [m]

-150

-100

-50

0

Path

loss

[dB]

PELFSL1d4



Empirical Models: Based on Measurements (called Channel Sounding)

•  Okumura-Hata model (1968) –  The most popular empirical model in cellular wireless design –  Based on measurements made in and around Tokyo –  Validity range of the model:

•  Frequency f between 150 MHz and 1500 MHz •  Transmit antenna height hb between 30 and 200 m •  Receive antenna height hm between 1 and 10 m •  Transmit-receive antenna distance r between 1 and 10 km

•  COST 231-Hata model (1999) –  Extension of the Okumura-Hata model for medium to small

cities to cover 1500 MHz to 2000 MHz

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Okumura-Hata Model

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Urban areas : LdB = A + B log10 R – E Suburban areas : LdB = A + B log10 R – C Open areas : LdB = A + B log10 R – D A = 69.55 + 26.16 log10 fc – 13.82 log10 hb

B = 44.9 – 6.55 log10 hb

C = 2 ( log10 ( fc / 28 ))2 + 5.4

D = 4.78 ( log10 fc )2 + 18.33 log10 fc + 40.94

E = 3.2 ( log10 ( 11.7554 hm ))2 – 4.97 for large cities, fc ≥ 300MHz

E = 8.29 ( log10 ( 1.54 hm ))2 – 1.1 for large cities, fc < 300MHz

E = ( 1.1 log10 fc – 0.7 ) hm – ( 1.56 log10 fc – 0.8 ) for medium to small cities



Empirical Pathloss Estimation

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Example of macrocellular measurement data from suburban area, and its pathloss model


Q3a:whichstatementisincorrect?A.  Thepathlossmodelhasmuchgreater

errorsatTx-Rxdistanceof6000mthanat1000m.

B.  Thegreatuncertaintyofthepathlossmodelisduetomobileloca2onvariability,whichwewouldneedothermodelstodescribethem.

C.  Thispathlossmodelmaybeusedreliablyevenwhenwemovethebasesta2onantennafromroo?optobuildingwall.

D.  ThepathlossexponentofthefiNedlineisgreaterthan2.



Ikegami Model

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LE =10 log10 fc +10 log10 (sinϕ )+ 20 log10 (h0 − hm )−10 log10 w −10 log10 1+3Lr2

"

#$

%

&' − 5.8

Φ  = angle between the street and the direct line from base to mobile Lr = reflection loss = 0.25

Defines excess losses due to rooftop-to-street coupling, on top of free space pathloss (r-2 dependence)



COST231 Walfish-Ikegami Model

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Restrictions :

•  Frequency f between 800 MHz and 2000 MHz •  TX height hBase between 4 and 50 m •  RX height hMobile between 1 and 3 m •  TX - RX distance d between 0.02 and 5 km


Q4a:whichstatementisincorrect?A.  Empiricalmodelsaresimplein

theirforms,butarepronetomeasurementuncertain2esandhencearelessaccuratethanphysicalmodels.

B.  Physicalmodelscancalculatepathlossatspecificsitesmoreaccuratelythanempiricalmodels,attheexpenseofgreatermodelcomplexity.

C.  TheOkumura-Hatamodelworksfordifferentenvironmentswithvariableterrainprofiles.

D.  TheIkegamimodelassumesthatenergyfromabasesta2oncomesmainlythroughdiffrac2onoverroo?opsnearthemobilesta2on.


Q4b:whichstatementisincorrect?A.  Empiricalmodelsaresimplein

theirforms,butarepronetomeasurementuncertain2esandhencearelessaccuratethanphysicalmodels.

B.  Physicalmodelscancalculatepathlossatspecificsitesmoreaccuratelythanempiricalmodels,attheexpenseofgreatermodelcomplexity.

C.  TheOkumura-Hatamodelworksfordifferentenvironmentswithvariableterrainprofiles.

D.  TheIkegamimodelassumesthatenergyfromabasesta2oncomesmainlythroughdiffrac2onoverroo?opsnearthemobilesta2on.


Q5a:wehavefourpropaga4>3.B.  4>1>2>3.C.  3>2>4>1.D.  2>4>1>3.E.  Noidea.

Base station

Mobile10 m

1000 mPlane earth 10 m

8 m1 m

321 4

1 23 4


Q5b:wehavefourpropaga4>3.B.  4>1>2>3.C.  3>2>4>1.D.  2>4>1>3.

Base station

Mobile10 m

1000 mPlane earth 10 m

8 m1 m

321 4

1 23 4



Contact Sessions for Topic 8•  Goals of the present exercise problems are to

–  Get acquainted with the cellular concepts of mobile communications and their most relevant propagation mechanisms (problem 1)

–  Be able to use physical models and compare their merits with respect to empirical models (problem 2)

•  During the contact sessions, you are –  solving the exercise problems by referring to relevant parts of the course

books. •  A limited number of course books are available in the room.

–  encouraged to discuss with other students and teachers. –  asked to contact teachers once your solutions are ready.

•  If you prepare exercise solutions in an electronic format (recommended), upload the solution to MyCourses first and then contact teachers.

–  asked to propose points for your ready solutions to the teachers. –  not given exercise points without discussing with teachers.

•  The discussions MUST happen in the contact sessions. –  reminded that the threshold deadline of Topic 5-8 exercises is November

17th.

aalto university school of electrical engineering elec-e4750 radiowave propagation … · 2016. 11....

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